THE
=GEOGRAPHY AND GEOLOGY=
OF
=SOUTH-EASTERN EGYPT.=
PLATE I.
[Illustration: OROGRAPHICAL MAP OF SOUTH-EASTERN EGYPT.
Ball. Geography & Geology of South-Eastern Egypt.
Photo-Metal-Process. Survey Dept. Cairo 1910. (60-190)]
MINISTRY OF FINANCE.
* * * * *
SURVEY DEPARTMENT, EGYPT.
* * * * *
THE
GEOGRAPHY AND GEOLOGY
OF
SOUTH-EASTERN EGYPT.
BY
=JOHN BALL, Ph.D., D.SC.,=
F.G.S., A.R.S.M., M.INST.C.E.
[Decoration]
CAIRO:
GOVERNMENT PRESS.
* * * * *
To be obtained either directly or through any Bookseller, from the
PUBLICATIONS OFFICE, Government Press, Bulaq; from the SALE-ROOM,
Geological Museum, Ministry of Public Works Gardens; or from the
SURVEY DEPARTMENT, Gîza (Mudiria).
* * * * *
1912.
=PRICE 40 P.T.=
=PREFACE.=
* * * * *
This book is an attempt to give a systematic account of the geography
and geology of South-Eastern Egypt according to the latest information
available. It is based on surveys which I carried out by order of the
Egyptian Government during the four years 1905-1908, and has been
written in the intervals of other official work during the succeeding
three years.
In the first or introductory chapter, I have given a summary, with some
criticisms, of previous accounts of the region. This seemed advisable
in that the literature, although not very extensive, is scattered in
books and papers in various languages, and is not always easy of access.
The second chapter is a concise systematic account of the district,
designed mainly as a summary for those who do not wish to go into the
details; it also contains sections dealing with matters of insufficient
importance, or of which our knowledge is too scanty, to be treated of
specially in the succeeding chapters.
The third chapter is an account of the surveying methods employed and
the principal geographical results obtained. The surveying methods are
treated at some length, firstly because an adequate specification of
the survey methods used is necessary for the assessment of the value
of any contribution to modern geography, and, secondly, because some
of the methods are either new or little known, and have been found
by experience to be specially adapted to the mapping of this type
of country. The principal geographical results are given, mostly in
tabular form, as exhibiting clearly the groundwork of the actual maps,
and as indicating a series of adequately fixed positions which may be
employed as a basis in any further surveys.
In the fourth to sixth chapters the drainage lines and hill features
are systematically described. A knowledge of the drainage lines, as the
key to a precise understanding of the relief, is nowhere more important
than in these deserts.
In the seventh chapter the important question of water supplies is
considered, and the positions and particulars of the various water
sources are tabulated for easy reference.
The eighth to tenth chapters deal with the various rocks occurring
in the district. The petrology of the region has been discussed with
some fulness, because while the district offers a remarkable wealth of
rock-species, well exposed in considerable masses, detailed studies
of Egyptian petrology have hitherto been few. My great regret in this
connexion is that I have been unable to add chemical analyses of the
rocks.
The eleventh chapter summarises the general geological structure and
history of the region, as gathered from a broader outlook over the
detailed geological evidences.
In the twelfth chapter I have set down the information I was able to
obtain regarding the territorial limits of the different Bedouin tribes
inhabiting the region.
The thirteenth and concluding chapter of the book consists of brief
notes taken on the return march to Port Sudan.
In regard to the cartographic material, most of which is new, special
attention has been given to the place-names, and it is believed
that these are correct in almost every case. But as the names are
in languages not understood by European draughtsmen, it is almost
impossible that mistakes have been entirely avoided; in any case where
map and text may disagree in spelling (the differences will, I trust,
never be so great as to leave doubts of identity), the text should be
followed in preference to the map, as mistakes in the text are usually
more easily perceived and corrected. I would remark that although the
whole of the field maps have been employed in preparing the small scale
ones, yet the full detail can be recorded only on the large scale maps,
which are given for the most important districts; a future explorer
would do well, therefore, to refer to the manuscript field maps which
are filed at the Survey Office at Gîza, before concluding that no more
detailed survey exists than is shown on the maps in this book.
The plates illustrating the scenic types are from my own photographs,
while those illustrating the natural-size aspect of the typical rocks
are reproductions from water-colour drawings which I made from actual
specimens. These coloured plates of rocks are mainly designed to enable
prospectors to identify readily the ordinary kinds of stone they meet
with in the field; but they will also serve to give to petrologists an
idea of the appearance of hand specimens of rocks from this part of
the world, which are not frequently met with in the great museums. The
text figures of rock sections I have mostly drawn at the microscope on
silver prints from photographic plates, the prints being afterwards
bleached out with mercuric chloride; they will appear slightly
diagrammatic in places, owing to the necessity of using lines and dots
for tints, but I find I myself get a better idea of a rock from a
drawing of this kind than from a photograph.
Much detailed surveying of this mountainous and arid region remains yet
to be done, especially in the districts round the heads of the Wadi
Alaqi, before our knowledge of it can be considered complete. It is
hoped, however, that a substantial beginning has been made towards this
end, and that future work may be facilitated by the observational data
recorded in the following pages.
JOHN BALL.
CONTENTS.
* * * * *
PAGE.
CHAPTER I. — Introduction 1
„ II. — General Description of South-Eastern Egypt 18
„ III. — Surveying Methods and Principal Geographical
Results 39
„ IV. — The Wadis draining Westwards to the Nile 78
„ V. — The Wadis draining Eastwards to the Sea 94
„ VI. — The Mountains and Hills 164
„ VII. — Water Supplies 234
„ VIII. — Geology.—Sedimentary Rocks 251
„ IX. — Igneous Rocks 262
„ X. — Metamorphic Rocks 331
„ XI. — Tectonics and General Geology 354
„ XII. — Tribal Boundaries 366
„ XIII. — Notes on the Road from Halaib to Port
Sudan 372
INDEX 379
* * * * *
LIST OF PLATES.
* * * * *
Plate. To face page
I. — Orographical Map of South-Eastern Egypt FRONTISPIECE.
II. — Sketch Map showing Drainage Basins 22
III. — Sketch Map showing Water Sources and Roads 26
IV. — Views of Ruins at Um Eleiga and in Wadi 30
Shenshef
V. — Views of Tomb of Sheikh Shadli and Bir Shadli 32
VI. — Map of the District of Nugrus and Sikait 106
VII. — Summit Views of Gebels Nugrus and Abu Hamamid 166
VIII. — Views from Gebel Migif 168
IX. — Descending Gebel Zabara 170
X. — Views from the Summit of Gebel Atut 172
XI. — Views in Wadi Muelih and of Gebel Selaia 172
XII. — Typical Views among the Mountains of Hamata
and Abu Hamamid 176
XIII. — Views on Gebel Kahfa 178
XIV. — Views of Gebel Kalalat and the Summit of
Gebel Faraid 192
XV. — Map of the District of Abraq and Abu Saafa 202
XVI. — Panoramas from the Summits of Gebels Niqrub
and Gerf 206
XVII. — Map of the District of Gebel Gerf 210
XVIII. — Map of the District of Meisah and Wadi Di-ib 218
XIX. — Map of the District of Elba and Halaib 226
XX. — Geological Map of South-Eastern Egypt 250
XXI. — Geological Map of Ras Benas 258
XXII. — Acid Igneous Rocks 268
XXIII. — Intermediate Igneous Rocks 284
XXIV. — Basic and Ultra-basic Igneous Rocks 300
XXV. — Metamorphic Rocks 334
XXVI. — Sketch Map showing Tribal Boundaries 368
XXVII. — Sketch Map of Route from Halaib to Mohamed
Ghul 372
XXVIII. — Sketch Map of Route from Mohamed Ghul to
Port Sudan 372
LIST OF ILLUSTRATIONS IN THE TEXT.
* * * * *
FIG. PAGE.
1. Sketch-map showing position of area described 1
2. Map of Abraq Springs 123
3. View from the summit of Gebel Elba 229
4. Granite of Gebel Fereyid 269
5. Red pegmatitic granite of Wadi Gemal 271
6. Biotite-granite of Gebel Abu Hegilig 273
7. Hornblende-granite of Gebel Elba 275
8. Hornblende-granite of Gebel Hamata 275
9. Granite-porphyry of Kreishim Hill 276
10. Quartz-felsite of the Wadi Huluz 277
11. Quartz-felsite from a dyke at Gebel Kolaiqo 278
12. Altered quartz-felsite of Gebel Igli el Iswid 281
13. Microperthitic structure in felspar of quartz-felsite of
Gebel Hadarba 282
14. Fractured felspar crystals in crushed quartz-felsite of
Wadi Huluz 282
15. Syenite of Gebel Zergat Naam 284
16. Syenite-porphyry of Gebel Zergat Naam 284
17. Trachyte from a dyke at Gebel Kahfa 285
18. Diorite of Gebel Allawi 287
19. Diorite of Wadi Baaneit 287
20. Augite-diorite of Wadi Um Hargal 289
21. Augite-diorite of Gebel el Anbat 290
22. Mica-diorite from a dyke at Gebel Abu Hegilig 291
23. Diorite-porphyrite of Gebel Abu Hodeid 292
24. Augite-porphyrite of Wadi Muelih 293
25. Kersantite of Gebel Fereyid 294
26. View near the top of Gebel Sufra 296
27. Andesite of Gebel Sufra 296
28. Gabbro of Gebel Dahanib 298
29. Gabbro of Um Eleiga 299
30. Hypersthene-gabbro of Hadal Aweib Meisah 300
31. Olivine-gabbro of Gebel Um Bisilla 301
32. Olivine-gabbro of Gebel Atut 302
33. Olivine-gabbro from hill S.-E. of Gebel Selaia 303
34. Troctolite of Gebel Um Bisilla 304
35. Pyroxene-granulite of Kolmanab Hill 305
36. Diabase from under the Nubian sandstone, Rod el Nagi 306
37. Diabase from Gebel Abu Hamamid 308
38. Olivine-diabase from a dyke at the junction of Wadis Gemal
and Huluz 308
39. Diabase from a dyke in Wadi Kreiga 309
40. Mica-diabase of Gebel Um Khariga 310
41. Basalt of Gimeida Hill 311
42. Basalt of Einiwai Hill 312
43. Amphibolite from hills near Gebel Um Gunud 317
44. Amphibolite containing olivine and bronzite, Qrein Salama 319
45. Serpentine (probably from a mica-peridotite), east of Erf
el Fahid 321
46. Serpentine (from lherzolite), hills near Wadi Um Khariga 322
47. Serpentine (from dunite), low hills near Bir Abraq 326
48. Serpentine (from dunite), low hills near Bir Abraq 326
49. Serpentine (from wehrlite), Gebel Gerf 327
50. Bronzite passing into serpentine, Gebel Gerf 327
51. Serpentine (from harzburgite,), Gebel Korabkansi 329
52. Crushing of quartz and felspar in granite-gneiss, Gebel Um
Rasein 334
53. Diorite-gneiss, Wadi Muelih 334
54. Crushed and altered syenite (schist), near Gebel el Anbat 339
55. Hornblende schist, Wadi Muelih 340
56. Schist composed of crushed volcanic rocks, Gebel Abu Hamamid 341
57. Hornblende schist, near Gebel Eqrun 343
58. Emerald and quartz, near Sikait 345
59. Tourmaline in talc-schist, Sikait 346
60. Section of sandstone at Gebel Um Khafur 358
61. Junction of sandstone and granite, west of Gebel Um Reit 359
62. Faulting near Wadi Saalek 359
* * * * *
=THE GEOGRAPHY AND GEOLOGY OF
SOUTH-EASTERN EGYPT.=
* * * * *
CHAPTER I.
* * * * *
=INTRODUCTION.=
* * * * *
[Illustration: Fig. 1.—Sketch-Map of Egypt. The shaded area shows the
district treated of in this book.]
The district treated of in this volume constitutes the extreme
south-east corner of Egypt, lying between the parallels of 22° and
25° of north latitude, and between the meridian of 34° E. and
the Red Sea coast. It comprises an area of about 56,000 square
kilometres, and includes some of the most mountainous and least
accessible portions of the Khedive’s dominions.
The district has been comparatively little visited by travellers, and
the literature concerning it is not very extensive. Berenice (_Jh_)[1]
was founded by Ptolemy II (285-247 B.C.), who named the town after his
mother, as a station at one end of the road for transporting goods
from the Red Sea to the Nile at Koptos (Quft). The emerald mines in
the Zabara area were worked at least as early as Ptolemaic times,
and gold mines in the south at a much earlier date.
References to this part of Egypt occur in the writings of STRABO,
DIODORUS SICULUS, and PLINY, as well as in PTOLEMY’s Geography and
the ANTONINE ITINERARY. Both Strabo and Pliny state that in Berenice,
as in Syene, the sun cast no shadow at the summer solstice from
which they inferred the town to be on the tropic of Cancer, though
in reality it lay in their day some twenty-five kilometres, and is
now about 28′, or some fifty-two kilometres, north of the tropic,
the difference being caused by the secular change in the obliquity of
the ecliptic since the beginning of the Christian era. Ptolemy gives
the latitude of Berenice as 23° 50′, which is only 5′ too low;
the _Smaragdus mons_, or emerald mountain, he places in latitude 25°,
which is about 15′ higher than the true position of Gebel Zabara
(_Ec_). Diodorus gives a very clear description of the working of
gold mines in the Eastern Desert in his day, by miserable convict
labour. The road from Koptos to Berenice is mentioned, with lists of
stations and water reservoirs and their distances from each other,
both by Pliny and the writer of the Antonine Itinerary; and though
Pliny gives fewer stations than the Itinerary, the two accounts agree
very closely in estimating the total distance at about 258 Roman
miles, which, so far as can be judged from a partial identification
of the stations marking the route, is pretty correct. The island
of Zeberged (_Ok_), on which occurs the green gem called peridot,
is probably the _Topazos Insula_ of Diodorus, and the _Agathon_ of
Ptolemy; but Diodorus gives its length as eighty stades (about twelve
kilometres), which is three times greater than its present size, and
Ptolemy’s latitude of 23½° is some 16′ too low. Ptolemy states
that the coast was inhabited by the _Ichthyophages_, or fish-eaters,
while the _Troglodytes_, or cave-dwellers, of Strabo, were probably
the workers in the mines.
The books of the Arab geographers, EDRISI and ABU EL FEDA, contain
some references to the roads and mines of the Eastern Desert, but
their descriptions are unimportant and contain frequent palpable
errors.
D’ANVILLE, in his _Mémoires sur l’Egypte_, Paris, 1766,
pp. 230-235, attempted to construct a map of the coast of the Red Sea
by combining the classical records with some early Portuguese and
other charts, but the latter were too crude to enable any approach
to be made to an accurate map.
It has been thought that BRUCE discovered the island of Zeberged
and the emerald mines of Zabara in 1769, but it is tolerably certain
that he saw neither of these places. He estimated the latitude of the
island he saw “pretty exactly” as 25° 3′, and its distance from
the coast as three miles,[2] whereas Zeberged is really in latitude
23° 36′, and is over thirty miles from the nearest coast. The
mines he saw were so close to the coast that he could walk to them
from his boat and back in less than a day (in fact he states that
they were only three miles from the coast), while both the Sikait
and the Zabara mines are over a day’s journey from the sea. Nor
could the mines have been the sulphur workings near El Ranga (_He_),
unless Bruce made a large error in his observation for latitude, for
the sulphur mines are about in latitude 24° 25′, and, moreover,
Bruce states that he found “brittle green crystals,” not sulphur.
It is to the French traveller CAILLIAUD[3] that we owe the first
modern account of Berenice and the emerald mines. Cailliaud was a
mineralogist, in favour with Mohammad Ali Pasha, who sent him on
two expeditions in 1816 and 1817 to search for mines in the Eastern
Desert. On his first expedition, starting from Redesia (near Edfu),
he discovered the rock temple of Seti I, forty-five kilometres
east of the Nile, and several ancient stations on his route, and
proceeded to the emerald mines of Zabara and the sulphur mines of
El Ranga. On his second expedition he took with him sixty Albanian
workmen to exploit the mines, and led them by nearly his former
route to Zabara, where they extracted ten lbs. weight of emeralds
(beryls) for presentation to the Pasha. On this second expedition
Cailliaud discovered the mines and ruins of Sikait, and also other
ruins in the Wadi Nugrus (_Ed_). Cailliaud’s drawings of the ruins
of Sikait greatly exaggerate their size and elegance.
JOMARD, in notes prefaced to Cailliaud’s account of his travels,
made a careful study of the probable positions of the ancient roads
and mines in this part of Egypt; he thought that Wadi Gemal Island
(_Hd_) was Zeberged.
In 1818, BELZONI,[4] fired by Cailliaud’s discoveries, set out
to discover the ancient Berenice. Starting from Edfu, he travelled
eastward for some days over Cailliaud’s route, then marched _via_
Bir Samut (where he discovered the ancient station) and Wadi Ghuel
to the Zabara mines, where he found Cailliaud’s miners still at
work. From Zabara he journeyed through the Wadi Sikait, passing the
mines and ruined temples which had been discovered by Cailliaud,
and down the Wadi Gemal to the sea. Proceeding then southward
along the coast, he examined the sulphur mines at El Ranga near
the mouth of the Wadi Abu Ghusun, and then made his discovery of
the ruins of the temple and town of Berenice, near the peninsula of
“Cape Galahen” (Ras Benas). The ruins were so inconspicuous as
to be only found with difficulty, and the temple was so buried in
sand that Belzoni could only make a very imperfect plan of it. The
ancient town he estimates to have covered a space near the temple
1,600 feet broad and 2,000 feet long. Leaving Berenice the same
day on which he made his discovery, Belzoni returned to Sikait by
way of Abu Greia, Haratreit (where he discovered ancient stations),
Hefeiri well, and the spring of Um Sueh. After copying some Greek
inscriptions at Sikait, he returned to Edfu by way of Wadis Hafafit
(_Dc_), where he found an ancient station, Abu Had, and Samut.
Belzoni’s map[5] of his routes is of course very crude and
erroneous, but the fact that he gives the names of the places he
passed enables one to reconstruct his routes on modern maps with fair
exactitude. His drawings of the ruins he visited are fairly accurate,
that of the rock temple of Sikait being a much truer picture than
Cailliaud’s.
The extreme south-east corner of Egypt was first explored in 1831
and 1832 by LINANT DE BELLEFONDS, who twenty years later published an
interesting account of his travels and discoveries.[6] The manner in
which Linant Bey’s expedition arose is very curious. He had read
the accounts of Diodorus and Arabic writers concerning the ancient
gold mines of the Eastern Desert, and when he accidentally discovered
small crystals of gold in quartzose detritus brought down the Wadi
Alaqi into the Nile by a storm torrent, he at once inferred that
this wadi would lead him to the mines. The Arabs told him, quite
correctly, that the down-wash had its origin far up the wadi, nine
days’ journey from its mouth. Reporting his discovery to Mohammad
Ali Pasha, that prince commissioned him to lead an expedition to
search for the mines. Starting from Aswan, Linant journeyed south-east
and discovered the ancient mines and ruins at Gebel Seiga (_Bp_), and
subsequently the more extensive workings at various places round the
head of Wadi Alaqi, such as Egat (_Ft_) and Darahib (_Gu_). From the
Alaqi district he proceeded northward to Bir Shinai (_Hr_), and thence
eastwards round the spurs of the mountains to Bir Meisah (_Kr_),
east of which he discovered the old mines of Romit (_Ls_). Crossing
the great Wadi Di-ib, he appears to have reached Bir Akwamtra (_Os_),
at the foot of Gebel Elba. His desire to explore the mysterious Elba
mountains was frustrated by the Arabs, and he only ascended a minor
peak before commencing his return march. From Elba he returned _via_
Bir Meisah, Bir Beida (_Ho_), and the Wadis Khashab (_Gn_), Hodein,
Rod el Kharuf (_Ch_), and Kharit to Daraw on the Nile, discovering
the springs of Abu Saafa (_Em_) in the course of his march.
Linant thus performed for the south portion of the district a similar
service to that which his compatriot Cailliaud had already done for
the north portion. His remarks on the people of the country, their
manners and customs, are no less interesting than his descriptions of
the ruins and mines which he discovered. The notes on certain points,
such as the manner of trapping the wild ass which then roamed these
deserts, are specially interesting as illustrating past usages. Linant
also compiled a small Bisharin-French vocabulary as an appendix to
his work. The large map accompanying his book, though it is well
engraved and depicts well the general mountainous character of the
country, is unfortunately full of large errors; Gebel Is (_Jt_), for
example, is placed more than sixty kilometres too far south; while
many of the place-names are either wholly incorrect or so loosely
transliterated as to be almost unrecognisable. But with all its
defects, Linant’s map remained the only source for cartographers
for a large portion of the Eastern Desert down to the time of the
commencement of the present survey; the map of Egypt published in
1905 by the Topographical Section of the British General Staff, for
instance, contains much of Linant’s material, though a comparison
of that map with the one joined to this report will show how great
were the errors in the matter thus incorporated.
WILKINSON[7] gives very brief notes on Berenice and the ancient roads
leading to it, as well as on the emerald mines of Zabara and the
ruins of the Sikait district. Wilkinson believed he had identified
all the ancient stations on the Koptos-Berenice road, besides another
smaller one not mentioned in classical itineraries. In the temple
of Berenice he found a small fountain, which is now in the British
Museum. But his work added little to what had already been learned
by Cailliaud and Belzoni regarding this part of Egypt.
In 1836, WELLSTED,[8] a lieutenant in the Indian Navy, who had been
employed in surveying the Red Sea coast, described the topography
of Berenice, and assigned to the place its true latitude of 23°
55′. He gives a plan and view of the temple, which he partially
cleared, and in which he found fragments of Greek tablets and of
a statue.
Between 1830 and 1840 important contributions were furnished to the
geography of Eastern Egypt by the surveys of the Red Sea, carried out
by MORESBY, WELLSTED, and other officers of the East India Company’s
Navy. Their sailing directions formed the foundation of the “Red Sea
and Gulf of Aden Pilot,” now published by the British Admiralty.[9]
Both the charts and sailing directions have been continually revised
by Admiralty surveys, and furnish much accurate information about the
coast. The principal errors are that almost the entire coast-line
between latitudes 22° and 25° is placed too far to the west,[10]
and some of the place-names are wrong, or at least unknown to the
local sailors of to-day. Such details of the inland relief as are
given on the charts are not correct, as was of course to be expected
in a hydrographic survey; but the main summits are fairly accurately
laid down, and their altitudes agree well with my determinations. Thus
the “Southern peak” of the chart, in latitude 23° 18′, is
Gebel Fereyid;[11] the “Black conical hill,” near Mersa Shab,
is Gemeida; “Scragged hill” is Qash Amir;[12] “High peak”
is Gebel Elba; “Castle hill” is Gebel Shendodai; and “South
peak” is Asotriba, the highest mountain of the Elba group.
In 1846, BARTH made a journey from Aswân to Berenice and thence
to Qoseir, and subsequently published a brief journal of his
expedition.[13] Going eastward from Aswân, he passed north of
Gebel Hamrat Mukbud (_Cf_), _via_ the Wadi Khashab, past the tomb of
Sheikh Shadli (_Df_) and the granite boss of Selaia (_Fh_), which
he thought to be of slate, and then descended to the coast by Wadi
Salib Abiad and Wadi Khoda (_Hf_). He discovered the old station
(now called Garia Kalalat) south-west of Berenice, on his way to the
temple, of which he took measures. Barth remarks on the insignificant
nature of the ruins and on the badness of the site for a town. On his
return journey, he discovered the wells and ruins of Shenshef (_Jj_),
where there are well preserved remains of substantial dwellings which
he thought denoted a settlement by people from Berenice. Ascending
the Wadi Shut after returning to Wadi Khoda, he turned westward and
reached the plain south of the Abu Hamamid-Hamata mountains. Crossing
this mountain track by the difficult pass of Hilgit, he descended
the Wadi Huluz (_Ef_), into Wadi Gemal, whence he turned northward
and visited the ruins of Sikait. From Sikait he proceeded by winding
tracks past Bir Ghadir (_Ec_) and on to Qoseir.
The next traveller to visit the district, VON HEUGLIN, examined
the country from the coast.[14] Sailing southward from Qoseir,
he discovered ruins which he thought to be those of Ptolemy’s
_Nechesia_, in latitude 24° 55′, a little south of Ras
Tundeba. Further south, he enumerates the various openings and
anchorages of the coast to Suakin. Gebel Hamata (_Gf_) he wrongly
thought might be the Alaqi of the ancient mining records. His
“Wadi el Hemmah” is doubtless Wadi Lahami (_Hg_). Rounding
Ras Benas, he passed the coral island of Mukawar (Geziret el Ras),
and anchored by the ruins of Berenice, which he states to be called
Sikait Qibli.[15] In and near the temple ruins von Heuglin found
copper nails, fragments of statues, Roman coins, a quartz sistrum and
pieces of beryl, besides potsherds and broken glass. Passing Mersa
Shab (Sherm Hel el Madfa), he notes a few fishermen’s dwellings on
Seyal Island, and a pearl fisher from Jidda plying his calling at
a small anchorage called Gota, near Ras Fatma. He mentions Kwolala
as “Geziret Elba,” close to the “peninsula of Halaib” (now
an island, Geziret Halaib).[16] The Elba mountains he states to be
the _Prionotus mons_ of Ptolemy. The “Sherm Qubeten,” which he
notes to the south of Halaib, is doubtless Mersa Qabatit of my map.
It is to the veteran African traveller SCHWEINFURTH that we owe
the first investigations of the Elba mountains, as long surrounded
with mystery as the stronghold of dreaded Bisharin tribes.[17]
Like von Heuglin, Schweinfurth visited the country from the
coast, making excursions inland. Starting from Qoseir in March,
1864, he proceeded with frequent stoppages to Suakin, spending
nearly six months in exploring the littoral districts. His chief
object was the investigation of the flora of the country, but his
accounts[18] contain much geographical and geological information
of great interest. He compares the coastal ranges of Africa with
the Cordilleras of South America, and the Abyssinian highlands with
Quito. The flora of the Elba district he found to be sharply marked
off from that of the rest of Egypt by the presence of large numbers
of plants of Abyssinian types. Among his geological notes, it is
interesting to come across a reference to serpentine, which I have
lately found to form the great mountain masses of Abu Dahr (_Gk_),
Korabkansi (_Fq_), and Gerf (_Hp_). Schweinfurth wrote, however, in
the early days of petrography, and his term “basalts” includes a
variety of fine-grained dark eruptive rocks which we should now call
by other names. The sulphur mines of El Ranga he characterised as
worthless, the mineral being in very small quantity. Schweinfurth’s
map of the Elba district was a great advance on anything of the
kind previously existing, though it contains many inaccuracies,
particularly of place-names, as was in fact only to be expected from
his very short stay in the locality. He remarked the separation
of Gebel Elba (_Pr_) from the more southern mountains, but failed
to notice that Qash Amir (_Os_), (the “Scragged Hill” of the
Admiralty Chart), is in its turn quite distinct from Elba, Halaib
is called Elei,[19] and the Geziret Halaib is shown as a peninsula;
Kwolala is called “Geziret Elei,” and the Geziret el Dibia
(the Elba Island of the charts) is called Geziret Abu Fendira by
Schweinfurth. My Wadi Shellal he calls “Wadi Heberah,” and Cape
Elba (my Ras Hadarba) is noted as “Ras Edineb.” His “highest
peak” (South Peak of the charts) is Asotriba, the highest mountain
of the group, lying just within the Sudan; the name Asotriba
(Schweinfurth’s “Soturba”) means “green mountain,” and
refers to the vegetation on its slopes. Schweinfurth’s experience
of the Bisharin led him to give them a very bad character, though
he gives high recognition to their beauty of feature and figure;
but being unfamiliar with their language was, he admits, an obstacle
to forming a fair judgment of them.
In 1873, Colonels PURDY and COLSTON, two American officers attached
to the Egyptian Army, were commissioned by the Khedive Ismail Pasha
to carry out a reconnaissance for a proposed railway line between
Berenice and Berber. Colston[20] travelled overland from Qena _via_
Qoseir to Berenice, discovering several ancient stations on his
way to join Purdy. Though Purdy sanguinely states[21] that “la
construction d’un chemin de fer de ce point (Berenice) à Berber
n’offrirait pas de grandes difficultés,” the reconnaissance
appears to have been singularly rough for a decision in so weighty a
matter. Distances were mere guesses, and the only instruments employed
seem to have been a compass, aneroid, and hypsometer. The compass
must often have been unreliable owing to magnetic rocks, which in
places deflect the needle as much as 40° from its normal position,
while the use of the aneroid was so little understood that Purdy
could actually write, in the concluding paragraph of his paper: “Je
me permets de rappeler l’attention sur les notes barométriques
jointes à ce rapport. A ce propos, je dois faire observer que
quoique l’anéroïde soit très sensible aux changements de
niveau, il ne l’est pas assez pour la pression atmosphérique,
et sa marche est excessivement irrégulière. . . . Il m’est
arrivé, par exemple, de constater, le matin, au moment du départ,
une différence sensible du point marqué le soir précédent à
mon arrivée.” Not only are many of the place-names given by Purdy
erroneous, but some of his most important statements are contrary to
fact; to take only a few examples, the Wadi Kalalat is confused with
Wadi Shenshef, and Gebel Shut with Gebel Dahanib, while it is stated
that no water exists between Gebel Dif (_Fm_) and Gebel Egat (_Ft_),
although there are several good wells between the two places. The
map accompanying Purdy’s paper is full of errors, and almost
worse than useless. Of Colston’s route from Qena to Berenice there
was no published cartographic record until 1891, when G. CORA[22]
endeavoured to place Colston’s track on a map from his manuscript
sketches. Cora’s map shows no new material except the route, and
even this cannot be very correct, for it is evident on comparison
with the results of the recent survey that Colston’s sketch map
was of the same rough and inaccurate character as Purdy’s.
In January 1889, GOLÉNISCHEFF made an expedition from the Nile
to Berenice and back. His object was to collect archæological
information, especially concerning the ancient roads and stations, but
the careful account[23] which he has given of his journey is also of
geographical interest. Starting from Redesia by Cailliaud’s route,
he examined the temple of Seti I, and then discovered the ancient
station of Abu Medrik[24] further to the south-east. Passing the
ruins at Samut and Dweig (_Cc_), he found another small station on
the way to Abu Had, and arrived at the station in Wadi Gemal (_Ed_),
near Wadi Hafafit. From the Wadi Gemal he proceeded _via_ the Wadis
Abiad (_Fe_), Abu Hegilig, Hefeiri, Abu Ghusun (_Ge_), Haratreit
(_Hf_), Khashir (in which another ancient station was discovered),
and Lahami (_Hg_), past the Abu Greia ruins, to Berenice. He returned
by way of Wadis Naait (_Hh_) and Lahami on to the plain of Kharit,
and thence past Hamrat Mukbud (_Cf_), _via_ the Wadis Khashab, Kharit
(_Ag_), and Abu Modellim, to the Nile. Golénischeff, besides giving
small plans of the various ancient stations and a carefully measured
plan of the temple of Berenice, made a comparison of his itinerary
with the descriptions of the old roads by classical writers and
by Colston. He considers there can be no doubt that Abu Greia is
the _Vetus hydreuma_ of Pliny, and the ruins in Wadi Khashir the
_Novum hydreuma_ of the same writer. The ruins in Wadi Haratreit he
considers to be the station _Cabalsi_ of the Antonine Itinerary,
_Apollonus_ being identified with the well found by Colston at
Hefeiri, _Falacro_ with the ruins in the Wadi Gemal, and _Aristonis_
with those in Wadi Dweig.
In 1891, FLOYER, at the head of a scientific exploring expedition sent
out by the Khedive Tewfik Pasha, travelled over the country north of
23° 30′, and his results were published in French in 1893.[25] A
little later, the geographical results of the expedition were embodied
in an English paper read at the Royal Geographical Society.[26] The
general map in the French essay is only on a very small scale, but the
English publication is accompanied by a much more illuminating map on
a scale of 1:760,320, reduced from one prepared by the Intelligence
Division of the War Office from Floyer’s original plane-table
sketches. This latter map, in spite of many errors and defects, was a
very great advance on anything which had previously appeared, and it
formed the principal source of geographical information concerning the
north part of the district at the commencement of my survey in 1905.
The geological observations made by Floyer during his expedition
formed the subject of a paper read by him before the Geological
Society of London in 1892.[27] This paper is chiefly remarkable for
the number of grave errors of observation into which Floyer’s
limited acquaintance with geology caused him to fall, and later
researches have fully justified the scepticism with which his
deductions were received by the Society. Thus, for instance, he refers
to the ancient schists and slates of Zabara as “blue clay,”[28]
and to the dark schists and diorite of Abu Hamamid and Abu Gurdi
as “compact granite.” The rocks which Floyer considered to be
“metamorphosed sandstone” are diorites and schists at Um Eleiga
and in the Wadi Gemal, and typical gneisses and granites in the Nugrus
and Hafafit ranges. Not a trace of sandstone has been found to exist
within many miles of the places where Floyer records its metamorphism,
nor has any evidence of the recent volcanic activity reported by him
(_Geog. Journal_, 1893, p. 430) been discovered.
An account of a short visit to the Elba district was published
by BENT[29] in 1896. Bent landed at Halaib and camped near Gebel
Shellal (_Qt_). He thinks that Halaib may have been the town of
_Aydat_ mentioned by the Arab geographers Abu el Feda and Edrisi,
and that it is a place of purely Arab origin. At Suakin el Qadim
(_Qs_) he found among the mounds nothing earlier than Cufic remains,
unless certain graves, formed of four large blocks of coral set
deep in the ground, may be looked upon as a more ancient form of
sepulture. His “Gebel Shendeh” should be correctly Gebel Shendib,
and his “Shendoeh” is correctly Shendodai; the “Riadh”
mentioned by him I have not been able to identify. His estimated
heights are considerably in error; thus Gebel Shendib is really
6,273 feet and Gebel Shellal 4,623 feet instead of the 4,500 feet and
4,100 feet which he gives. The paper contains interesting remarks on
the Hamedorab tribe, which Bent was informed totalled only some 300
fighting men in the entire district from Asotriba to Ras Benas. The
reference to the sheikh as “the batran” is due to a misconception;
Batran was the late sheikh’s first name, and is not a title of
station. The map accompanying Bent’s paper is only to a very small
scale, and formed practically no addition to existing knowledge.
MACALISTER[30] has given a detailed and interesting account of the
Sikait district (_Ed_), with special reference to its geology, as
the result of an expedition there in 1899. The small scale sketch
map of the route followed in reaching the mines from the valley is
not very correct, but the detail maps of the Sikait neighbourhood
give an accurate representation of the area in which the mines
are situated, while the geological notes give an excellent idea
of one of the most highly metamorphic areas of the entire Eastern
Desert. Macalister gives some notes also on the ruins and the people
of the neighbourhood. His experience of the Ababda as workers was very
unfavourable; though his characterisation is unfortunately only too
well merited by a large section of the tribe, it is probable that a
longer acquaintance with Arabs would have enabled him to select men of
a better class. A sufficiency of good men for a caravan of 130 camels
cannot be raised without great expenditure of time and care, even by
those who have lived for many years among the Arabs, and a few bad
characters in a desert camp soon exert a bad influence over the rest.
The brilliant series of investigations carried out by the officers
accompanying the Austrian research ship “POLA” in the Red Sea in
the winter of 1895-96, though chiefly concerned with oceanographic
questions, contain not a few observations of interest connected with
the land.[31] The positions determined include Sherm Sheikh, Berenice,
St. John’s or Zeberged Island, and Halaib. The latitudes observed
agree well with the values which I found by triangulation.[32]
For longitude the method used was the transport of chronometers,
and this method is liable to such considerable errors that we
need have no hesitation in preferring my triangulation values,
especially as our latitudes are in agreement. The observations
made by the officers of the “Pola” on the compass-variation at
Berenice and Halaib are of considerable importance as enabling us,
by comparison with my own observations at the same places, eleven
and twelve years later, to obtain a reliable value for the rate of
secular change of this magnetic element in the district. A large
scale map of Halaib is given, and amongst other observations of
interest to the geographer in South-Eastern Egypt are analyses of
the water at Halaib, a series of pendulum observations which show
a decided increase in the force of gravity over the sea as compared
with the intensity over the land, and descriptions with figures of
some of the reptiles which are found in the region.
Turning now to the work of the GEOLOGICAL SURVEY in the district,
the maps and descriptions in the present volume are the result of
surveys carried out by me in the three seasons 1905-1908, or about
twenty-two months’ work in all. The survey was commenced primarily
with the view of enabling mining concessions to be accurately marked
out. How little possibility of this existed so recently as 1902 may
be gathered from the fact that although a ministerial order of that
year had defined the administrative frontier between Egypt and the
Sudan as being a line joining certain important mountains and wells,
which were named, yet it was impossible to lay this frontier down
correctly on a map because the geographical positions even of these
important features were uncertain to many kilometres.
The main interest in the field methods used, which will be described
in detail in a subsequent chapter, lies in the fact that many of
them are wholly or in part new, having been devised as the work
proceeded to meet the special exigencies of the case. The costly
nature of camel-transport, and the relatively small value of
the country, precluded the employment of the ordinary sequence of
survey operations, and it was necessary to carry on reconnaissance,
precise triangulation, detailed topographical mapping, and geological
surveying, all at once, and to move rapidly so as to cover a large
area in a moderate time. Starting from a measured base near Gebel
Muelih, which had been previously connected by triangulation with
the Nile Valley, a network of large triangles was thrown over
the country. The essential feature of the triangulation was the
employment of observations at relatively few occupied main summits,
to fix large numbers of points by intersection; in some cases over
a hundred triangulation points were sighted from a single occupied
station. The triangulation was continued so as to join to a second
base line near Gebel Um Harba (_Ck_), and was also connected on to
main points in the trigonometrical survey of the Sudan, thus linking
up a continuous chain of triangles from Alexandria to Berber. The
total number of main (occupied) stations was sixty-four, while the
intersected points numbered 450. In addition to these, about 1,200
minor points were fixed by subsidiary triangulation from short
local bases.
Levels were taken trigonometrically for all points fixed by
triangulation, using the actual sea-level as the datum. The altitudes
of nearly all camps were likewise found trigonometrically, and
between successive camps aneroid readings, adjusted to the initial
and terminal points of the day’s march, were employed to supplement
trigonometrical determinations made on the journey.
For the control of the maps, latitudes and azimuths were taken at
intervals, the former by equal altitudes of three or more stars,
the latter by elongations of close circumpolar stars.
The topographical sketching, carried out on plane-tables on a scale
of 1:100,000, was based on the points triangulated, these being
computed in camp and plotted by their geographical coordinates
as much ahead of the lines of march as possible. When marching,
plane-table stations were fixed by re-section from three or more
triangulated points, the compass being useless owing to abundance
of magnetic rocks. Details along the line of march were put in by
tacheometric readings from the stations, using specially devised
long distance methods. But the greater portion of the sketching was
done from the mountain tops while occupying them as trigonometrical
stations, and for this again special methods, involving an extensive
use of vertical angles, were employed. On an average, about thirty
square kilometres were sketched in during each day’s march, and
about 400 square kilometres from each main trigonometrical station,
where it was usually necessary to remain for at least a week to get
sufficiently clear weather for the more distant sights. It was not,
of course, possible to sketch every portion of the area in uniform
detail, for some parts lay so far from the line of march and from
the triangulation stations that little or no detail was visible. The
lacunæ were filled in as far as possible in the field from guides’
statements, taking care on the field maps to distinguish parts so
filled as only approximate. A few additions near the west limit
of the map have been added from reconnaissance surveys by various
colleagues of the Survey Department. For details of the upper part of
the basin of the Wadi Alaqi, I have taken advantage of an admirable
reconnaissance-survey of this tract recently made by Mr. J. MORROW
CAMPBELL, B.SC., F.R.G.S., for the Egyptian Options, Ltd., who
kindly placed their map at the disposal of the Government. My
triangulation gave the positions and altitudes of all the principal
peaks of this region, and thus enabled Mr. Campbell’s map to
be accurately adjusted to the Survey positions, and his drainage
lines and other topographical details have been inserted with great
advantage to the map, which would otherwise have been almost blank in
this particular area. Mr. Campbell’s map does not, unfortunately,
give any altitudes, and the only altitude data for the orographical
sketching were the peaks and other points of connexion with the Survey
map; but by taking into account the depth of shading of the different
hill masses and the known altitudes determined by triangulation,
it is believed that a fairly approximate picture of the orography
has been obtained.
The sea coast north of latitude 24° 10′ was adapted from the
Admiralty Chart, fitting it on to coast points trigonometrically
fixed. South of 24° 10′ the coast was surveyed in detail by means
of depression angles from the occupied peaks of the triangulation. The
local circumstances, in the existence of high mountains pretty
close to the sea, are so favourable to the employment of this
method, that it is confidently believed that the maps represent
a considerable advance in accuracy over the Admiralty Charts. It
was frequently possible to check the accuracy of the coast-line
delineation by plane-table rays, and it was invariably found that
the errors were insensible, even on the fairly large scale employed
in the field-maps. The coast-line shown is the high water-line. The
tidal change of level, though it is generally less than a metre,
uncovers in many places extensive coral reefs at low water, but no
attempt was made to map these.
Very special care was taken with place-names, which are transliterated
on the Egyptian Government system. It may be remarked that this system
is based on the Arabic _spelling_, not on pronunciation. Thus, in this
part of the country, the letter _g_ is almost always soft, like an
English _j_, and the _q_ is always sounded like a hard _g_. The same
system was used for the Bishari and Ababda names, these being first
written by a guide in Arabic characters and then transliterated. It
is believed that the orthography is correct in almost all cases.
The geology was examined along every line of march, and additional
specimens were obtained by sending guides to collect rocks from
mountains otherwise unvisited. Where possible, the principal
geological boundaries were drawn direct on the plane-table sheets in
the field, and the remainder have been placed from field notes. The
limits of the different igneous and metamorphic rocks shown on
the geological map aim only at showing general relationships,
for in many cases it is difficult, owing to insensible gradations,
to decide exactly where granites and diorites end and gneisses and
schists begin, while in other places rocks of two or three distinct
species are so intimately mixed that the boundaries could not be
shown on the small scale used, even if the exact limits were traced
by a life-time’s work; in these latter cases the areas are coloured
in accordance with what appeared to be the dominant rock within them.
Throughout the three seasons’ work I was accompanied by Dahab
Effendi Hassan, who rendered useful assistance in booking angles and
in reconnaissance, and in the third season Mr. O. N. Bakewell also
accompanied me and gave me much useful help. The Egyptian unskilled
staff employed consisted almost entirely of Bedouin and comprised on
an average about twenty-five camel drivers (for thiry-five baggage
camels), six porters, three guides, and two postmen, all placed
under an Arab sheikh.
The total cost of the field-work was approximately L.E. 5,090, or
about 150 milliemes for each square kilometre of country mapped
in detail. Nearly two-thirds of the entire amount were expended
in camel-transport, the remainder representing the expenditure on
salaries and allowances of the author and assistants engaged in
actual surveying operations.
* * * * *
[Footnote 1: The references in parentheses after place-names refer
to their positions on the map, Plate I.]
[Footnote 2: _Bruce’s Travels to discover the Sources of the Nile._
Halifax, 1845. pp. 78-80.]
[Footnote 3: CAILLIAUD, _Travels in the Oasis of Thebes and in the
Deserts east and west of the Thebaid_, edited by JOMARD. Translated
from the French. London, 1822. This work contains two small maps and
many engravings. (The map of the Eastern Desert is unfortunately
wanting in the Khedivial Library copy, which is the only one I
have seen.)]
[Footnote 4: BELZONI, _Narrative of the Operations and Discoveries
in Egypt and Nubia, and of a Journey to the Coast of the Red Sea,
in search of the ancient Berenice_. London, 1820.]
[Footnote 5: _Plates illustrative of the Researches and Operations
of G. Belzoni in Egypt and Nubia._ London, 1822. (This is a large
folio atlas of 44 plates.)]
[Footnote 6: LINANT DE BELLEFONDS, _L’Etbaye_, Paris (N. D., but
the title of the map accompanying the work gives the date as 1854).]
[Footnote 7: WILKINSON, _Topography of Thebes and General View of
Egypt_. London, 1835. pp. 415-422. _Modern Egypt and Thebes._ London,
1843. Vol. 2, pp. 389-394.]
[Footnote 8: WELLSTED, _Notice of the Ruins of Berenice_. Journal
of the Royal Geographical Society. London, 1836. pp. 96-100.]
[Footnote 9: _Red Sea and Gulf of Aden Pilot._ 5th edition. London,
1900 (with several later supplements). _Admiralty Charts of the Red
Sea._ Sheets 2 and 3.]
[Footnote 10: At Halaib Fort the difference is as much as 1′ 53″,
or nearly 2 miles; _see_ p. 66.]
[Footnote 11: This should not be confounded with the higher Gebel
Faraid to the northward.]
[Footnote 12: Qash Amir is quite a separate mountain from Gebel Elba,
not part of the same range as the chart indicates.]
[Footnote 13: BARTH, _Reise von Assuan über Berenike nach
Kosser_—Zeits. für allgem. Erdkunde. Berlin. Vol. VII (1859),
pp. 1-31. (There is no map to this work, but the route followed
is easily traceable on a modern map owing to the place-names being
given in the journal.)]
[Footnote 14: V. HEUGLIN, _Reise in Nordost Africa und längs des
Rothen Meeres im Jahre 1857_. Petermann’s geogr. Mittheilungen,
1860. pp. 332-335. (This paper is accompanied by a map, which is,
however, lacking in the copy of the Khedivial Library).]
[Footnote 15: This I think is an error. A small isolated granite hill
west of Berenice is called Sikeit, and has been visited by Barth and
myself; but it is devoid of ruins. My Arabs called Berenice _Medinet
el Haras_.]
[Footnote 16: There was no “Geziret Elba” known to the sailors
of Halaib at the time of my survey. The “Elba Island” of the
Admiralty Chart is called Geziret el Dibia; it is a very small island,
which looks like a boat from a distance.]
[Footnote 17: Though the Bisharin are now very orderly and friendly,
the ancient dread of their country still persists to such a degree
that it is almost impossible to persuade Ababda Arabs to go near
the Elba district.]
[Footnote 18: SCHWEINFURTH, _Reise an der Kuste des Rothen Meeres
von Kosser bis Suakin_, Zeits. für allgem. Erdkunde. Berlin, Band
XVIII (1865), pp. 131-150, 283-313, 320-384. A special account of
the Elba district is given with a map, in another paper, _Das Land
am Elba- und Soturba-Gebirge_ in Petermann’s geog. Mittheilungen,
1865. pp. 330-340. Schweinfurth also published several other papers
dealing with the rich botanical results of his expedition.]
[Footnote 19: I found many of the natives could not recognise the name
Halaib, which has become the official name of their village. They
call it “Oleiyib,” sounding the final consonant only slightly;
so that Schweinfurth’s “Elei” is not very different from the
local name.]
[Footnote 20: COLSTON, _Journal d’un voyage du Caire
à Keneh, Bérénice et Berber_. Bull. Soc. Khédiv. de
Géographie. 1886. pp. 489-568.]
[Footnote 21: PURDY, _Reconnaissance entre Bérénice et
Berber_. _Ibid._ pp. 431-435, with a map.]
[Footnote 22: CORA, _La route de Kéneh à Bérénice levée en 1873,
par le Colonel R. E. Colston_. Bull. Soc. Khéd. de Géog. Cairo,
Sept. 1891. pp. 533-538, with map.]
[Footnote 23: GOLÉNISCHEFF, _Une Excursion à Bérénice_. Recueil
de Travaux. Vol. XIII (1891), pp. 75-96.]
[Footnote 24: Golénischeff names this place _Abu Greïa_, a name
which he remarks is the same as that of a station near Berenice. Garia
Abu Medrik is the name given to it by the Arab guides accompanying
the Survey expeditions.]
[Footnote 25: FLOYER, _Etude sur le Nord Etbai_. Cairo, 1893.]
[Footnote 26: _Further Routes in the Eastern Desert of Egypt._
Geog. Journal. London, 1893. pp. 408-431.]
[Footnote 27: _Notes on the Geology of the Northern Etbai._
Quart. Journal Geol. Soc. London, 1892. pp. 576-582.]
[Footnote 28: Professor HULL, in the discussion on Floyer’s paper,
suggested, even in the absence of specimens, that Floyer’s “blue
clay” was really a decomposed Archæan schist. My observations
have proved the sagacity of this suggestion.]
[Footnote 29: BENT, _A visit to the Northern
Sudan_. Geogr. Journal. London. Vol. VIII (1896), pp. 335-353.]
[Footnote 30: MACALISTER, _The Emerald Mines of Northern
Etbai_. Geog. Journal. London. Vol. XVI (1900), pp. 537-549.]
[Footnote 31: _Berichte der Commission für Oceanographische
Forschungen._ Sechste Reihe, Wien 1898, and Siebente Reihe, Wien,
1901.]
[Footnote 32: _See_ p. 65.]
CHAPTER II.
* * * * *
=GENERAL DESCRIPTION OF SOUTH-EASTERN EGYPT.=
* * * * *
In this chapter will be given a brief general account of the district,
under the heads of:—
1. Extent.
2. Relief.
3. Hydrography.
4. Coast-line.
5. Climate.
6. Scenery.
7. Animal and Plant Life.
8. Water Supplies.
9. Geology.
10. Mineral Products.
11. Antiquities.
12. Inhabitants.
13. Languages.
14. Industries.
15. Communications.
16. Government.
The subjects of topography, water supplies, and geology, will be
further considered more fully in succeeding chapters.
=Extent.=
As already mentioned in the introduction, the district treated of
in this volume lies between the parallels of 25° and 22° of north
latitude, and between the meridian of 34° E. and the Red Sea. It
comprises an area of about 56,000 square kilometres (22,000 square
miles).
=Relief.[33]=
The higher mountains of the Eastern Desert generally form the
watershed between the Nile and the Red Sea. This watershed is much
nearer to the coast than to the Nile, with the result that the
eastward drainage is much steeper than to the west.
Commencing from the north (_see_ the orographical map, Plate I),
the principal mountain masses are:—
(i) The Migif — Hafafit — Nugrus — Hangalia — Zabara group
(1,505 metres[34]), cut off to the south by the Wadi Gemal (_Fd_).
(ii) The Abu Hamamid — Hamata — Abu Gurdi group (1,978 metres),
limited on the south by the Wadi Lahami (_Hg_).
(iii) The Um Gunud — Dahanib — Batoga group (1,270 metres), lying
between Wadi Lahami on the north and Wadi Khoda (_Hj_) on the south.
(iv) The Abu Dahr — Orga — Um Tenedba group (1,131 metres),
separating the drainage of Wadi Betan (_Fl_) from Wadis Khoda and
Rahaba (_Hl_).
(v) The Faraid group, the _Mons Pentadactylus_ of Ptolemy, comprising
some very remarkable granite peaks (1,366 metres), lying near the
coast between Wadi Khoda and Wadi Rahaba.
(vi) The Awamtib — Abraq — Dif — Aqab el Negum — Mishbih
group (1,353 metres), forming the tripartite watershed between the
great Wadi systems of Kharit and Alaqi on the west, and that of Wadi
Hodein on the east.
(vii) The Gerf — Abu Hodeid group, a mighty mass rising to 1,736
metres, lying between Wadi Hodein (_Jn_) and Wadi Hasium (_Hs_).
(viii) The Meisah — Adar Qaqa — Is group, between the Wadis
Hasium and Di-ib (_Mr_).
(ix) The Elba — Shendib group (1,912 metres[35]), a great mass of
spiky mountains lying near the sea between Wadi Di-ib and the coast.
Besides these main groups, there are numerous more or less isolated
mountains, of which Gebels Abu Khrug (_Bd_, 870 metres), Hamrat
Mukbud (_Cf_, 890 metres), Zergat Naam (_Ej_, 845 metres), and the
two Niqrubs (_Fn_ and _Fo_, 829 metres and 1,078 metres) are examples.
Some of the mountains, especially the granite “bodkin” of Gebel
Faraid (_Hl_), and some of the peaks of the Elba group, appear to
be unclimbable. A few others are rather dangerous of ascent, as,
for example, Gebel Abu Hamamid (_Ef_) on account of its steepness,
and Gebel Abu Dahr (_Gk_) by reason of combined steepness and rotten
rock, which comes away in tons at a touch. The highest peak of all
within the district, Gebel Hamata (_Gf_), is a comparatively easy
climb from the north.
=Hydrography.=
The course of the main watershed which parts the Red Sea and Nile
drainages is highly irregular both in altitude and direction, as will
be evident from the orographical map (Plate I), on which it is shown
by a red line. From Gebel Hamrat Wogud, in the north, it passes east
of Gebel Atut, thence through the high masses of Gebels Hangalia,
Nugrus, Hafafit, and Migif, beyond which it drops southward through
the low country round Gebel Abu Had. Entering the mountains again
at Gebel Nukheira, it takes an eastward bend, passing along the
great ridges of Gebels Abu Hamamid, Um Usher, Um Hasidok, and Ras el
Kharit. Striking southward across the head of Wadi Kharit, it courses
through the mountains of Mikbi and Abu Gurdi, thence dropping to the
south on the plain near the hills called Marwot Elemikan. Turning here
sharply westward over the plain, it passes through the hill-mass of
Gebel Abu Derega and on to Gebel Zergat Naam, south-west of which it
crosses the low tract at the head of Wadi el Arned to the sandstone
plateaux of Dagalai, whence it courses a little to the west of
Gebel Um Reit and enters the mountainous tract of Gebel Aqab el
Negum. Its further course has not been traced in detail, but from
guides’ statements and the indications of the main drainage-lines
it is believed to run as shown on the map, in a great curve through
the two sharp peaks of Gebel Sheyenit to the west of Gebel Mishbih,
and then in another flatter curve south-eastwards to Gebel Soaorib,
at the head of Wadi Hasium. Continuing along the mountain ridges of
Gebel Soaorib, it crosses to Gebel Is,[36] separating the Wadi Is
from the heads of Wadi Alaqi on the Sudan frontier.
The watershed is for a great part of its course quite impassable for
camels. The principal places where it can be crossed are at the head
of Wadi Nugrus, near Abu Had, the Wadi Marasan between Huluz and
Wadi el Sheikh, the heads of Wadi Lahami, Wadi el Fil, Wadi Arned,
and Wadi Um Reit, passes at Aqab el Negum and Hamrat el Feg, near
Gebel Mishbih, the head of Wadi Hasium, and the pass of Adar Ameit,
north of Gebel Is. All these places are practicable for baggage
camels, though in some of them, as, for instance, at the head of
Wadi Nugrus, care is required because the track is steep and stony.
The principal drainage-basins are shown on the small scale map
on Plate II. The westward drainage ultimately reaches the Nile by
the three main trunk wadis of Shait, Kharit, and Alaqi; Shait and
Kharit enter the Nile Valley at Kom Ombo, while Alaqi debouches near
Dakka. The eastward drainage is much more complex, the principal
trunk wadis, such as Um Khariga, Gemal, Khoda, Rahaba, Hodein, Ibib,
Di-ib, and Serimtai, being separated by very numerous minor wadis
draining independently to the sea.[37]
Nearly all the wadis contain vegetation in the form of trees and
bushes, and plant life flourishes as a rule far more luxuriously in
wadis draining seawards than in those leading to the Nile. Feqoh,
Naam, and the lower reaches of Hodein are, however, exceptionally
barren. Forming, as they do, the only possible roads, furnishing
the entire supply of camel food, and containing most of the wells,
the wadis are to the desert what the Nile is to Egypt proper. The
intervening mountains are of no interest to the Arabs, except when
they contain water-reservoirs. Hence the place-naming starts from
the wadis, even the smallest of which have names unless they are
barren. Mountains are generally named after the nearest wadi, and may
thus have two names when situated between two wadis, the particular
name used depending on which side the mountain is seen from.
=Coast-line.=
The coast-line of this part of Egypt is somewhat irregular, the
peninsula of Ras Benas forming a prominent projection in latitude
24°. In the south part of the area the eastward extension of the
country, culminating in Ras Hadarba (Cape Elba of existing maps),
is very marked, extending nearly to 37° of east longitude. The
coast is almost entirely fringed by coral reefs, passage through
which is only possible at certain points, and then only with the
utmost care in navigation.[38] Between the feet of the mountains and
the sea there extends a gently sloping plain, varying in width from
about eight to twenty-five kilometres, covered with sand, over which
the drainage meanders in shallow courses, often only traceable by
the vegetation which occurs along them. A rather surprising result
brought out by the levelling observations is that the slope of the
coast plain, even where it looks flattest and sandiest, is as steep
as the floors of some of the wadis draining on to it, and several
times more steep than the beds of the wadis which drain westwards
to the Nile, its fall seawards averaging six metres per kilometre
and reaching over ten metres per kilometre in some sections.
=Climate.=
The climate of the district is predominantly hot and dry to the
west of the watershed, hot and moist eastward of it; but very cold
weather is apt to prevail for a few weeks in January and February,
with strong north winds, on both sides of the watershed, and the
transition from piercing cold to great heat at these times is often
brought about very suddenly by a change of wind direction. There
is seldom any frost, but water-bags are occasionally frozen on the
mountain tops at night. Cool north-west winds prevail in the north
part of the area, while hot damp winds from the south-east are usual
in the south. In the central part, round Berenice, absolute calms are
frequent.[39] The highest mountain-masses are frequently swathed in
clouds for weeks together, especially from January to March. The hot,
dry, sand-laden winds called _Khamsin_ occasionally blow for four
or five days together in March and April; at these times the shade
temperature rises to over 45° C., and the air is thick with sand and
dust. Rain falls in most years, but its quantity is very variable;
in some years there is barely enough to keep the wells supplied, and
much of the vegetation withers; in others, heavy storms produce wild
downrushes in the wadis, filling them for short periods with raging
torrents. Curious electrical and optical phenomena can sometimes be
seen on the mountain-tops during storms and in mists.[40] The Elba
region is seldom free from clouds, and receives far more rain than
any other portion of the area, forming in fact the northern limit of
the rainy tropical zone; it is in consequence relatively well wooded,
while the other mountains are a dreary waste of naked rocks.
PLATE II.
[Illustration: SKETCH-MAP OF SOUTH-EASTERN EGYPT.
Showing Drainage-Basins.
Ball. Geography & Geology of South-Eastern Egypt.
Photo-Metal-Process. Survey Dept. Cairo 1910. (60-190)
Scale 1:2,000,000.]
=Scenery.=
The predominant types of scenery are extensive sandy plains and
gaunt rugged mountains. In the low-lands, pleasant relief from
the stony monotony is afforded by the trees and scrub which occur
along most of the wadis, though their struggle for existence is
often evidenced by miles of withered and blackened scrub in places
which a few years ago were green and flourishing. The bareness
of the mountains becomes slightly relieved in the Elba district,
where beautiful trees and flowering plants thrive high up the
mountain-side along all the drainage lines. As to the forms of
the mountains, one sees extensive broken sandstone plateaux at
Gebel Abraq (_El_), remarkable rounded granite bosses at Gebels
Muelih (_Ab_), Nugrus (_Dc_), Selaia (_Fh_), and Um Rasein (_Jr_),
jagged and spiky granite peaks in the mountains of Faraid (_Jk_),
Qash Amir (_Os_), and Elba (_Ps_), and broken masses of gneiss,
dark schists and serpentines at Gebels Hafafit (_Dc_), Hangalia
(_Dc_), Abu Hamamid (_Ef_), Hamata (_Gf_), and Gerf (_Hp_). Perhaps
the most remarkable of all the peaks are those of Faraid (_Jk_),
which from the north look like the expanded fingers of a huge hand,
whence they received their name of _Mons Pentadactylus_ in antiquity,
while one specially sharp peak is styled very appropriately “the
Bodkin” on Admiralty Charts. The mass of Elba forms a very fine
view from the north, but the prevalence of clouds about its summits
frequently hides it from view for months together. The views from the
mountain-tops are extensive and beautiful, especially at sunrise and
sunset, when the peaks take on wonderful colours, and the views from
the summits when the entire lower landscape is bathed in clouds,
through which only the higher peaks project like islands from
a great sea, are not less remarkable. Though a good look out was
kept from the highest mountains across the sea, the mountains of
the opposite shore of Arabia were never with certainty made out;
the cone of Zeberged Island was, however, often seen. It is stated
by d’Anville, on the authority of Castro,[41] that both the Arabian
and African mountains can be seen from the summit of Zeberged.
=Animal and Plant Life.=
Both animal and plant life is mainly confined to the drainage
lines. Of wild animals suitable for human food, gazelles can be
shot fairly frequently in the south part of the area, but are very
scarce in the north. Sand grouse and partridges can occasionally
be obtained round Abu Saafa, while doves are very abundant in the
groves near Bir Akwamtra, at the foot of Gebel Elba. Ibex were never
seen with certainty, though their horns and lairs were often found
on the mountains. Conies inhabit the rocks near Bir Abraq and Bir
Madi. The wild ass has disappeared from the area, as also has the
ostrich, though fragments of ostrich eggs picked up here and there,
and drawings of this bird on the rocks, attest its presence here in
recent times. Vultures, kites, and ravens are everywhere in evidence,
and several kinds of smaller birds, such as swallows and wagtails,
are often seen about the greener wadis. Lizards of many kinds are to
be seen. Scorpions and snakes are seldom met with. Of butterflies
and moths, especially the latter, many varieties occur. The common
fly occurs in such numbers as to be a great pest, but mosquitoes and
sand-flies are practically absent. Camel ticks infest the ground
under all trees used as shade by travelling Arabs. Earwigs are in
some places very abundant, and a great variety of beetles and bugs
occur. Near the sea, whole armies of crabs are to be seen marching
on the shore, and hermit crabs are very numerous in all sorts of
gasteropod dwellings.
Of plant life the district contains a great variety. The north and
central parts of the area contain the same trees and bushes as abound
further north in Egypt,[42] and camel food is moderately abundant. As
Elba is approached, many beautiful flowering plants not found further
north are met with, while in the clefts of the slopes of Elba itself
is a far richer vegetation than occurs wild in any other part of
Egypt. I found the approach to Elba was stopped for baggage camels
some four kilometres from the summit owing to the closeness of the
trees, and the ascent on foot up the clefts of the mountain-face
for the remainder of the way was more like going through an English
wood than up a desert mountain. Many varieties of sweet-smelling
flowers and some fruit-bearing trees unfamiliar in Egypt were seen,
while mosses and lichens covered the tumbled masses of granite in
many places. Schweinfurth, who examined the botany of this region
in 1864, found that of 300 species of plants collected in the Elba
district, the vast majority were of Abyssinian types; scarcely 100
were living in other more northerly parts of the Eastern Desert of
Egypt, while still fewer are indigenous to the Nile Valley, and only
fifteen species were of those found wild in Europe.[43]
=Water Supplies.[44]=
The sources of water comprise _galts_ (rock basins forming rain
water reservoirs in the mountains), springs and wells. Of these,
_galts_ yield the purest water, and form the principal supply of the
pastoral Arabs, except in years of no rainfall, while springs and
wells, the latter usually rude excavations in the alluvia of wadis,
are most used by travellers from their easier accessibility. Small
_galts_ are called _megal_ (Ababda) or _megwel_ (Bisharin); they
are frequently accompanied by small springs.
The small scale map on Plate III, which shows all sources known
to exist within the area, gives a good idea of the distribution of
water supplies. Water is scarce in the western parts of the country,
Bir Abu Hashim being the only source within a radius of about sixty
kilometres of itself, but _galts_ and wells are fairly frequent among
the mountainous tracts further east. The springs of Abraq and Abu
Saafa are the most important sources in the central area. The portion
of the country under the Sudan Administration is far richer in water
that the Egyptian part, containing numerous fine wells and springs,
such as Birs Meneiga, Abu Hodeid, Akwamtra, and Frukit. The coast
plain is waterless, except for salty wells near the sea.
Water can usually be obtained at intervals of about two or three
days when on the march, and in some parts much more frequently. The
water of certain wells and springs has a purgative effect due to
the absorption of magnesium salts, especially after a long interval
without rain. That of others, again, such as Muelih and Shalatein,
is so salty as to be only drinkable by camels.
=Geology.[45]=
The rocks composing this part of Egypt are principally igneous and
metamorphic deposits of very ancient origin. Granite is most prominent
in the Nugrus, Faraid, and Elba areas, schists and diorites cover a
large portion of the remaining country, and huge masses of serpentines
form the mountains of Abu Dahr, Korabkansi, and Gerf. Of sedimentary
rocks, plateaux of Nubian sandstone (Cretaceous) cover large areas
round Bir Abraq and westward of it, while a narrow belt of the
same rock also occurs along the sea coast in the north part of the
district. Gypseous limestones (Miocene?) form the hills of Ras Benas
and occur along the coast north of Wadi Lahami, as well as in small
areas near the coast further south in the neighbourhood of Halaib.
PLATE III.
[Illustration: SKETCH-MAP OF SOUTH-EASTERN EGYPT.
Showing the Water-sources and the Roads connecting them.
Ball. Geography & Geology of South-Eastern Egypt.
Photo-Metal-Process. Survey Dept. Cairo 1910. (60-190)
Scale 1:2,000,000.]
Crushing of the older rocks is almost everywhere strongly evidenced,
but faulting is difficult to trace except in the sandstone areas,
where it is strongly marked. The presence of clearly defined
overthrust faulting in the Abraq area shows that tangential earth
movements, so rare in this part of the world,[46] have not been
altogether absent.
=Mineral Products.=
The mineral resources of this part of Egypt are not of very great
importance, owing partly to its inaccessible situation and desert
character. Gold and copper ores occur in places; other localities
contain beryl and peridots, while others, again, bear iron ores,
gypsum, sulphur, steatite, asbestos, and magnesite, and good building
stones abound over large areas.
The presence of ruins and excavations at places like Hangalia, Sikait,
Zabara, Romit, and Darahib, are evidence of mining activity in the
past, but the mean nature of the accommodation for the workers,
and the presence of old stone hand mills where gold was the thing
sought for, confirm the statement of Diodorus[47] that the mines
were worked by miserable convicts.
In recent years much prospecting has been done to test whether the
ancient mines could be developed and made commercially productive
under modern conditions. In the case of many areas, including that
round Darahib, the mines of which are believed to be those referred
to with a map in the Turin papyrus of the Nineteenth Dynasty,[48] the
prospecting licences have been surrendered to the Government because
the results were unfavourable. In a few other cases prospecting is
still being carried out, and in three localities the results have
been sufficiently encouraging for exploitation to be undertaken.
The following tables, compiled from information supplied by the
Mines Department, give particulars of the prospecting licences and
mining leases at present (1912) held within the area described in
this book:—
PROSPECTING LICENCES.
--------+----------------+---------+----------+-----------------------
Licence|Date of Licence.|Principal|Holder of |Situation of Area
No. | | Mineral | Licence. |licensed.
| | sought. | |
--------+----------------+---------+----------+-----------------------
49 | Nov. 1, 1909 | Gold. |Mr. Mack. |Kurdeman district.
| | | |
50 | „ 1, 1909 | „ | „ |Sabahia district.
| | | |
75 | May 14, 1911 | „ | „ |North-east side of
| | | |Gebel Zabara.
| | | |
59 | Feb. 17, 1910 |Sulphur. | Mr. |Gebel Ranga, near the
| | |Venizelos.|mouth of Wadi Abu
| | | |Ghusun.
| | | |
60 | „ 17, 1910 | „ | „ |Adjoining the
| | | |foregoing.
| | | |
61 |March 19, 1910 | „ | „ | „ „ „
--------+----------------+---------+----------+-----------------------
MINING LEASES.
------+--------------+----------+----------+-----------+-------------
Lease|Date of Lease.| Period | Mineral | Holder of |Area leased.
No. | |for which |exploited.| Lease. |
| | granted. | | |
------+--------------+----------+----------+-----------+-------------
13 | Dec. 1, 1910 |30 years. | Gold. | African |25 acres
| | | |Reefs, Ltd.|near Gebel
| | | | |Um el Tiur
| | | | |el Tahtani.
| | | | |
15 | Jan. 1, 1912 |30 years. | Gold. |Mr. Wells. |25 acres
| | | | |near Gebel
| | | | |Sukari.
| | | | |
55 | June 1, 1906 |30 years. | Peridot. | Peridot & |Zeberged
| | | | Egyptian |(St. John’s
| | | | Gems Co., |Island).
| | | | Ltd. |
------+--------------+----------+----------+-----------+-------------
Of the above three mining leases, the last mentioned (the Peridot
and Egyptian Gems Co., Ltd.) is the only one under which any
considerable exploitation has been carried on, large numbers of
beautiful peridots having been obtained from the mines. The two
gold mining undertakings have been commenced too recently for much
to have been as yet accomplished.
=Antiquities.=
The archæological remains of pre-Arab times in this part of Egypt
comprise the small ruined temples of Berenice and Sikait, the ruins
of stations along the old mining roads, the ancient mines with the
rude habitations of the miners, and sundry markings on rocks near
the roads.
The =Temple of Berenice= is a low inconspicuous structure measuring
only some ten metres square, containing five small rooms and a tiny
corridor and staircase.[49] Owing to its exposed situation on the
coast and the soft limestone (from Ras Benas) of which it is built,
it is in a very dilapidated condition, and it is difficult to make
out many of the inscriptions on its walls. The axial direction of
the temple (63° 20′ east of true north) appears to show that
it was oriented to face the rising sun at the summer solstice. Of
the village (one can hardly call it a city) of Berenice, only
insignificant remains exist near the temple. The houses were mere
hovels built of rough lumps of coral.
There are three =temples in Wadi Sikait=; they are small rock-hewn
structures in even worse preservation than that of Berenice.[50]
Many attempts have been made to trace the =ancient mining roads=
mentioned by classical writers. The stations on the road from _Koptos_
(Quft) to Berenice, enumerated by Pliny and Antoninus, have not been
with certainty identified. The absence of any reliable map of the
main features of the country has hitherto prevented travellers from
locating the positions of stations found, while in careful surveying
it has generally been necessary to travel by other roads than the
ancient ones, so that it cannot be hoped that all the ruined stations,
many of which are invisible till one is close to them, have been
included in the maps. Now that all the principal features of the
country have been accurately laid down, it will be much easier for
future travellers to locate precisely any ruins they may come across.
Of the road leading from _Contra-Apollinopolis_ (Edfu) to the
emerald mines of Sikait and Zabara, much more is known, this route
having been traversed by Golénischeff[51] and most of its stations
located by the Geological Survey. Leading from Edfu, past Bir Abad,
the ruins of a large station and rock temple occur at a distance
of about forty-five kilometres from the Nile, at a place now called
_Kanais_ (the churches), where a well yielding good water was sunk
three years ago by the Mines Department. About forty-five kilometres
further on is the station called Gariat Abu Medrik, where there are
two ancient stucco-lined cylindrical reservoirs, but no well. At the
next station, called Samut, there is a good well in the centre of a
large rubble ruin. As all the stations just mentioned lie outside
the limits of the maps which accompany this memoir, I give their
approximate geographical positions below:—
------------------+-----------+------------+-----------
Station. |Latitude N.|Longitude E.| Altitude
| | |above Sea.
------------------+-----------+------------+-----------
| | | metres.
| | |
Edfu | 24° 58′ | 32° 54′ | 90
| | |
Kanais | 25° 0 ′ | 33° 19′ | 205
| | |
Gariat Abu Medrik| 24° 55′ | 33° 41′ | 295
| | |
Samut | 24° 49′ | 33° 54′ | 340
------------------+-----------+------------+-----------
The next station after Samut appears to have been the ruins near
Gebel Dweig. Further on, after passing over the watershed, is
another station with two cisterns in a semicircular enclosure. The
road continues past Gebel Abu Had to the Wadi Gemal, where there are
two more cisterns, this time in a triangular enclosure, and thence
up to the Wadi Nugrus and Wadi Sikait to the mines. The Edfu-Sikait
road may have joined the Quft-Berenice road at the Wadi Gemal station.
A third ancient road is believed to have led northward from Berenice
to Qoseir, along the coast; while a fourth, from near Dakka on the
Nile up the Wadi Alaqi to the gold mines of the south, is now a
regular route to the Nile Valley Company’s mine of Um Gariart.
The =ancient emerald mines of Zabara and Sikait= consist of numerous
irregular shafts, mostly of no very great depth, excavated in schists
of micaceous and talcose types. The =old gold mines=, such as those
at Sukari, Um Eleiga, Seiga, Romit, and the Darahib district, are on
a considerable scale, excavations having been carried on in quartz
veins to fair depths. The dwellings at the mines were for the most
part only miserable hovels of rubble stone. A view of those of Um
Eleiga is given on Plate IV. The ancient quartz-grinding mills, mostly
made of a hard diorite, are frequently found among the ruins of the
hovels. There is no clear evidence that any of the mines yielded a
very rich output; the workings were of the nature of penal settlements
(Prof. Mahaffy[52] has aptly termed them a “tropical Siberia”)
in times when life and labour were cheap, and a very moderate yield
may under those conditions have been satisfactory.[53]
PLATE IV.
[Illustration: Ruins of Um Eleiga. Gebel Abu Dahr in the Background.]
[Illustration: Ruins in Wadi Shenshef.]
Besides those at the mining camps and stations, there are some
other extensive collections of ruins in the district, two of the
most considerable being at Shenshef and Bir Meneiga. The =ruins at
Shenshef= (_see_ Plate IV) are in part those of well-built houses,
furnished with doors and windows, formed of slabs of fissile quartzose
schist, quarried in the neighbouring hills. There are wells at
Shenshef, but apparently no mines; the presence of watch towers on
the hills, and the peculiar situation of the place, suggest that it
may have been a slave dealer’s stronghold where slaves were herded
till they could be shipped from Berenice. The better houses may have
been those of the overseers, while the ruder hovels accommodated the
slaves, and sentinels at the watch towers prevented any attempt at
escape. The =ruins at Bir Meneiga=, though extensive, are very rude,
and probably only represent a camping ground near the springs. A large
rubble enclosure near Abraq springs has been thought by Purdy[54]
to have been a hunting station of the Ptolemies.
In many places there are =marks and drawings on the rocks= near
roads. These are frequently spirited representations of animals,
among which the ostrich is often seen. At the Galt el Aguz, near
the watershed at the head of one of the branches of Wadi Garara,
the drawings are accompanied by rude Greek inscriptions. At Abu
Saafa, one of the springs issues from a niche cut in the sandstone,
having a carved cornice with the remains of a Greek inscription on it.
Another class of remains are found scattered over the area in the
form of =cylindrical rubble piles=, four metres in diameter and from
one to two metres high. The natives consider these to be tombs of
pre-Arab date.
Of =Arab tombs= in the area, the most considerable is that of
Sheikh Shadli, near Gebel Abu Hamamid, a view of which is shown on
Plate V. It is a well-built tomb of several domes, inhabited by a
Moorish guardian. A yearly pilgrimage is made to this place by the
Ababda Arabs, who hold the memory of Shadli in high veneration. The
next largest tomb is probably that of Sheikh Hamid, near Abraq
springs. Near the nose of Ras Benas is a large sheikh’s tomb,
where sailors perform their devotions, and smaller tombs of the
same type, built of drift-wood, are to be seen at other points near
the coast. Cemeteries of small Arab graves exist near every well
and spring.
=Inhabitants.=
The South-Eastern Desert of Egypt is inhabited by nomad Arabs of the
various Ababda and Bisharin tribes.[55] Ababda (Ashabab and Meleikab)
occupy the country north of Muqsim and Bir Shalatein, while Bisharin
(Hamedorab, Kurbeilab, Koatil, and Balgab) inhabit the country to
the south.[56] Only guesses are available as to their numbers, but
it is not probable that they comprise so much as one inhabitant for
each five square kilometres. A casual journey through the country
would lead one to think that it was inhabited to an even less
degree, but the Arabs mostly camp in selected narrow wadis out of
sight of the traveller. They are a people of good physique, hardy,
intelligent, and fair workers if once their employer knows how to
handle them. They share, however, in the universal Bedouin dislike to
protracted regular work; after a few months of regular routine, even
the semi-nomad routine of a survey-expedition, they experience strong
desires for their own independent roaming life, and it is impossible
to retain them for longer periods. Many of the Ababda who are settled
near the Nile have lost their true desert character, and on desert
expeditions men of this class are far less satisfactory than nomads;
they do not know the country, but fear the desert and are continually
desirous of returning to the valley. The better desert guides,
on the other hand, love the wilderness, and they have a perfectly
marvellous geographic instinct. The skeleton on which they arrange
their knowledge is always the system of drainage. If a map of their
country is laid before them, and a few points named to them, they
will delight in tracing out and naming all the wadis and peaks. But
they have very vague ideas of proportion, and can only read a map
when it is laid on the ground in its true orientation with respect
to the meridian. The Ababda are generally regarded as the best type
of Egyptian desert Arab, while my experience of the Bisharin of the
Elba district is that they are superior, in industry, intelligence,
truthfulness, and orderliness, to the Ababda.[57] It is, however,
necessary either to understand the Bishari tongue, or to have men
who can interpret into Arabic, as the great mass of the Bisharin
understand only their own language, which is quite different from
Arabic.[58] Education is very backward, but there is a _kuttab_
(elementary school) at Halaib, where instruction in Arabic reading
and writing is given to boys. All the Arabs are of course Moslems,
but they are not at all fanatical.
PLATE V.
[Illustration: Tomb of Sheikh Shadli.]
[Illustration: Bir Shadli.]
The manner of life of the Arabs is very simple. Most of the men have
only a single cotton wrap about their middle, though some wear the
ordinary galabia and cotton drawers. Their camps are rude tents of
matting about two metres in diameter, but the men commonly sleep in
the open, sheltering themselves from winds by their camel saddles,
covered only with their cotton wrap, which they spread over their
entire bodies, including their heads. They wear no head covering,
having heavy “mops” of curled black hair plentifully supplied
with mutton fat. Their food consists almost entirely of milk and
meat, of which their flocks and herds give them a plentiful supply;
they eat but little bread, but they are fond of a kind of gruel of
flour and water, and of dates, which are imported from Arabia _via_
Suakin. Only a few of them smoke tobacco, and that generally in
soapstone pipes which they carve out for themselves. Intoxicants are
unknown amongst true desert Arabs. For arms, they carry swords and
knives, seldom fire-arms. Of their tribal customs, I saw but little;
Linant de Bellefonds gives an interesting account of them in his
“L’Etbaye.” On festive occasions, camel-racing and dancing
are favourite amusements.
Slavery appears to be non-existent at present, for in the course of
my twenty months’ wanderings I received no complaint under this
head, as I should almost certainly have done had any oppressive
servitude existed.
=Languages.=
My own study of the Ababda and Bishari tongues has been mainly
confined to their geographical terms. The Ababda nowadays almost
all speak Arabic, and most of their place-names are either Arabic or
closely akin to it. A marked feature of their tongue is a fondness
for diminutives. Thus we have _Sellim_ and _Seleim_, _Hafafit_ and
_Hefeifit_, _Faraid_, and _Fereyid_, _Wadi_ and _Wadai_, in each of
which the second of the pair is a diminutive formed by vowel-change,
generally accompanied by a change in the placing of the stress. The
commonest special geographical terms in Ababda country are: _erf_,
a ridge; _rod_, a tributary wadi; _talet_, a small tributary wadi;
_kab_, a watershed or pass; _hamrat_, a (red) granite mountain;
_zergat_, a black mountain; _galt_, a rock basin containing rain
water; and _megal_, a small water hole. Thus we have such names as
_Hamrat Selma_, _Zergat Naam_, and so on, the name often giving a
clue to the nature of the rock.
As soon as one passes into Bisharin country the change in the
nature of place-names is very striking. The definite article is no
longer _el_, but _o_, _u_, _ei_, _e_ (masc.), and _to_, _tu_, _tei_,
_ti_ (fem.). Many place-names end in _ai_ and _oi_. The principal
geographical terms are: _kwan_, a wadi; _da-aiyob_, a depression from
which there is no drainage outlet; _aweib_ and _riba_, a mountain;
_kulet_, a hill; _megwel_, a water hole; _adar_, red; _hadal_,
black; _sotai_, green; _eire_, white; _sarara_, deep; _salala_,
rather deep (applied to wells). Hence we get such combinations as:
_Hadal Aweib Meisah_, the black mountain near Wadi Meisah; _Eir
Arib_, the white (granite) rock; _Sarobi Kwan_, the wadi where
the Sarob plant (_Capparis sodada_) grows; _Bir Sararat Seyet_,
the deep well in Wadi Seyet, and so on. A mountain called _adar_ is
generally of red granite, while one called _hadal_ is usually diorite
or serpentine. _Asotriba_, the green mountain south of Gebel Elba,
receives its name from the vegetation on it.
=Industries.=
The principal industries carried on by the desert Arabs are the
rearing of camels, sheep and goats, especially the first-named. The
Bisharin devote much attention to camel-breeding, and supply many
animals annually to the Coast Guard Administration. Their camels are
very superior animals, and need to be hardy in order to negotiate
the steep mountain passes of their country. Sheep and goats can be
bought cheaply in the south, and are driven in to Aswân for sale
at the higher rates there prevailing. It is common to find a flock
of hundreds of sheep being watered at wells such as Bir Abu Hashim
and Qoleib on the route to Kom Ombo; but many animals drop and die
on the weary march from well to well.
Charcoal burning has been practised, especially in the Ababda country,
but is not much carried on now; this industry deserves strong
opposition, for it only impoverishes the country, and the _seyal_
trees are few enough for the support of camels in years of drought.
In recent years some employment has been found for the Arabs
by prospectors for mining companies, both as miners and for
camel-transport, and they are occasionally, as in the present
expedition, employed on Government work.
For the information of future travellers, it may be worth
while to mention the prices paid for local labour on the survey
expeditions. The men and animals were all the best obtainable of
their particular class, and the prices include saddles and fodder
for camels, their own provision of water and food for the men, and,
in the case of sheikhs, postmen, and guides, their riding camels
and fodder:—
_Mills, per day._[59]
Responsible sheikhs in charge of all Arabs 200
Skilled guides (also employed as beacon builders) 150
Postmen journeying regularly to and from the
Nile Valley 150
Baggage camels, each to carry 300 pounds’ load,
with one driver to every two camels, the drivers
to act as general labourers at a camp and to
collect wood and water and to carry supplies up
the mountains when required 120
Riding camels 120
Porters 70 to 80
A small amount of agriculture is practised in the Wadi Di-ib, slightly
south of the Sudan frontier, but there is none actually within the
district here described. My camels were fed for some time on _durra_
(Indian corn) brought from Wadi Di-ib.
A little fishing is carried on near Berenice and at Mersa Shab and
Halaib, but only for the food of the fishermen, who subsist almost
entirely on it, and thus recall the _Ichthyophages_ of Ptolemy. When
I had abundance of excellent fish at Shab and Halaib, I noticed
that but few of my Bisharin cared to partake of what was to me a
very welcome change of diet.
Halaib is the only permanent village, and even it is merely a
miserable collection of wooden huts and tents, where trade is
confined to dates, fat, corn, sugar, and such like necessaries;
supplies are brought by boat from Suakin and sold to the local Arabs.
=Communications.=
There are numerous camel-roads connecting the various wells with each
other and with the Nile, the principal of which are indicated on Plate
III (p. 26). The most usual starting points from the valley are Edfu,
Kom Ombo, Aswân, Dakka, and Berber. The roads lie mostly along wadis,
and are far from being very direct, being necessarily so chosen as
to pass water supplies and to avoid very steep places. From Aswân
or Kom Ombo, Berenice can be reached in about seven or eight days
by luggage camels, and the roads are fairly good; water is least
scarce on the Kom Ombo road, which takes advantage of the wells of
Qoleib and Abu Hashim. Between any two wells, there are generally
several possible roads. The one taken by any particular traveller is
naturally that which his guides happen to know best, or that along
which the most camel food is to be found at the time; hardly any two
Europeans have journeyed by precisely the same road. A “road”
in desert parlance is only a track by which camels have passed at
some time or other; there is nothing of the nature of a _made_ road,
even along the ancient routes mentioned in the Antonine Itinerary; and
the tracks are sometimes obliterated by sand. Since the opening up of
Port Sudan, the Elba district is most easily reached from that place,
whence it is about 340 kilometres distant, by two roads of nearly
equal length, one skirting the coast and the other more inland; the
latter passes good wells at about two days’ intervals.[60] To reach
Elba from the valley, a camel journey of more than 500 kilometres is
necessary whether Aswân, Dakka, or Berber be the starting point. The
ports of Berenice, Shab, and Halaib are only touched occasionally
and irregularly by coasting boats and Coast Guard steamers. News is
passed orally among the wandering Arabs with remarkable rapidity,
but naturally it frequently gets somewhat modified in transit.
=Government.=
The geographical frontier between Egypt and the Sudan is the 22nd
parallel of north latitude. But for administrative purposes it
has been found convenient to consider all Bisharin Arabs as under
the Sudan Government, and all Ababda under that of Egypt. The
administrative frontier therefore runs between the districts of the
two main tribal divisions, along a zigzag line from Gebel Muqsim,
_via_ Gebel Um el Tiur el Foqani, Gebel Niqrub el Foqani, and Bir
Meneiga, to Bir Shalatein on the coast.[61] A territory of some
16,000 square kilometres in the extreme south-east corner of Egypt
is thus placed for purposes of government under the Sudan mudiria
of Berber, under which arrangement a moawin and small police force
are maintained in the fort of Halaib. The remainder of the area is
administered by the Egyptian mudir of Aswân. In Egypt, the Arabs
are not taxed except in respect of any lands they may own in the
Nile Valley. In the Sudan a tax is levied on each tribe in return
for police protection and other advantages; the tax is paid very
willingly, for the Bisharin are less poor than the Ababda, and
thoroughly appreciate the advantage of good government, while they
have unbounded faith in the justice of Anglo-Egyptian officials in
settling their disputes. One of the incidents which most strongly
impressed itself on my remembrance during my travels in the district
was the meeting near Gebel Korabkansi of an English inspector from
Berber, to whom a number of Bisharin Arabs engaged in disputes stated
their rival claims quietly and reasonably, both sides having the
utmost confidence that the judgment given would be just and fair. In
Egypt, the Arabs are less friendly in their feelings towards the
government, and prefer to settle their differences among themselves;
a circumstance no doubt due to the fact that Egyptian governors
have had their hands full with matters connected with the valley,
and have had no time to become acquainted with Bedouin ideas and
customs, while the Arabs, independent for centuries and very poor,
are afraid of misunderstanding and taxation. It would, I think, be
unfair to tax the true desert Arabs of Egypt, even to the moderate
extent which is done for the Arabs of the Sudan, for their country
is much more barren than that of the Bisharin, and their sources of
income are consequently fewer. In a year of little or no rainfall,
there is not enough vegetation to feed their animals, so that many
are lost, and the only way a tax could be raised at such times would
be by cutting down trees for charcoal; but, as already mentioned,
any encouragement of the charcoal industry would soon impoverish the
country still further, the thorny acacia trees being the principal
reserve camel food in rainless years. That so many Ababda are
settled in and near the Nile Valley is possibly in part due to their
having been driven from the desert by the growing scarcity of trees
consequent on the prosecution of the charcoal industry in the past.
* * * * *
[Footnote 33: The mountains and hills will be found described in
fuller detail in Chapter VI.]
[Footnote 34: The altitudes refer to the highest points of the
groups.]
[Footnote 35: This is the altitude of Shendib, the highest of the
group in Egypt; but the peaks of Asotriba, which is part of the same
mass lying within the Sudan, rise considerably higher.]
[Footnote 36: In the map on Plate I, I have shown the watershed
crossing directly from Gebel Soaorib across the high intervening
mountains to Gebel Is, which is how it appeared to me from my station
on Hadal Aweib Meisah. But Mr. Morrow Campbell’s map (referred to
on p. 15) shows the heads of Wadi Soaorib to extend further west
than I could see them; and if this is correct, as it probably is
since Mr. Morrow Campbell doubtless approached the watershed more
closely than I did, the watershed between Gebel Soaorib and Gebel
Is lies further west than I have shown it on Plate I. In drawing
the wadis on the geological and tribal maps on Plates XX and XXVI,
I have shown the westward extension of the heads of Wadi Soaorib
according to Mr. Morrow Campbell.]
[Footnote 37: The wadis will be found described at length in Chapters
IV and V.]
[Footnote 38: See the _Red Sea and Gulf of Aden Pilot_, published
by the Admiralty.]
[Footnote 39: See my short paper on the meteorology of the Berenice
district in _Survey Notes_, Sept. 1907, p. 325.]
[Footnote 40: I have given short accounts of some of these phenomena
in _Survey Notes_, April 1907, p. 219, and in the _Cairo Scientific
Journal_, May 1908, p. 206.]
[Footnote 41: D’ANVILLE, _Mémoires sur l’Egypte_. p. 234.]
[Footnote 42: _See_ BARRON and HUME, _Topography and Geology of the
Eastern Desert, Central Portion_. Cairo, 1902. pp. 98-104.]
[Footnote 43: SCHWEINFURTH, in _Petermann’s Mittheilungen_, 1865.]
[Footnote 44: For a fuller description of the water-sources of the
region, _see_ Chapter VII.]
[Footnote 45: For a fuller account of the geology, _see_ Chapters
VIII to XI, and the geological map on Plate XX.]
[Footnote 46: SUESS, _The Face of the Earth_. Miss Sollas’
translation. Vol. I. Oxford, 1904. p. 376.]
[Footnote 47: Lib. III, 12-14.]
[Footnote 48: _See_ DUNN, _Notes on the Mineral Deposits of the
Anglo-Egyptian Sudan_, published by the Sudan Government. Khartoum,
1911. p. 15.]
[Footnote 49: For a plan of the temple and notes on its inscriptions,
_see_ GOLÉNISCHEFF, Une Excursion à Bérénice, _Recueil de
Travaux_. XIII (1891). pp. 75-96.]
[Footnote 50: MACALISTER, _Geog. Journal_. Vol. XVI (1900). p. 546.]
[Footnote 51: _Op. cit._ Golénischeff gives sketch plans of the
stations.]
[Footnote 52: _The Empire of the Ptolemies._ London, 1895. p. 130.]
[Footnote 53: DIODORUS (I. 49) probably greatly exaggerated the
value of the produce of the mines. _See_ UHLEMANN, _Handbuch der
gesammten aegyptischen Alterthumskunde_, Zweiter Theil, Leipzig,
1857, pp. 148-151, where a very clear account, mainly derived from
Diodorus, is given of the mining methods used by the ancients.]
[Footnote 54: _Bulletin Soc. Khéd. de Géogr._ 1886. p. 443.]
[Footnote 55: According to Mr. Bramly (The Anglo-Egyptian
Sudan. 1905. p. 91) the Bisharin are not true Arabs, and are of
Hamitic descent.]
[Footnote 56: Regarding the geographical boundaries of the different
tribes, _see_ Chapter XII.]
[Footnote 57: Schweinfurth did not have the same experience in 1864;
but one speaks as one finds. Schweinfurth was reluctant to pass
judgment, not knowing the language, and possibly in the interval
since 1864 the people have improved.]
[Footnote 58: On the Bishari language, _see_ ALMKVIST, _Die
Bishari-sprache_, Upsala, 1881-1885; REINISCH, _Die Bedauye-sprache
in Nordost-Africa_, Wien, 1893; and REINISCH, _Wörterbuch der
Bedauye-sprache_, Wien, 1895.]
[Footnote 59: The millieme is practically equivalent to an English
farthing.]
[Footnote 60: For a detailed description of this road, _see_
Chapter XIII.]
[Footnote 61: Arrêté of the Ministry of Interior, Egypt, June
25, 1902.]
CHAPTER III.
* * * * *
=SURVEYING METHODS AND PRINCIPAL GEOGRAPHICAL RESULTS.=
* * * * *
=Triangulation.=
=Base-Lines=—The triangulation was commenced by measuring a base
line[62] near Gebel Muelih by means of a 100-metre steel tape, which
had been previously standardised at the Khedivial Observatory. A level
tract having been selected, in such a position as to afford easy
connection with points already triangulated from the Nile Valley,
a line about two and a half kilometres long was ranged out, along
which wooden pegs were driven flush with the ground at 100-metre
intervals. The inequalities of the ground between the pegs were
levelled off by tiny embankments and cuttings, so as to enable
the tape to lie flat. On each peg was nailed a zinc plate having a
millimetre scale running in the direction of the line. In measuring,
the tape was laid on the ground, stretched to a constant tension by a
spring balance at each end, in such manner that its end marks fell on
the zinc scales, and readings were simultaneously taken on the scales
at the two ends. Temperatures were taken in several places along
the tape by mercurial thermometers. The operation of measurement
was carried out in the early morning, so as to avoid any large
difference of temperature between the ground and the air. The levels
of the pegs were found by spirit levelling. After correction for the
initial error of the tape, temperature, stretch, and inclination,
the true length of the base-line reduced to sea-level was found,
as the mean of two separate measurements at different tensions,
to be 2,482·280 metres. The azimuth of the line was found by
observations of _Polaris_ at elongation to be 30° 30′ 6″ E. of
N. The geographical position of the west end of the line was found by
triangulation-connexion with the Nile Valley by Mr. Villiers Stuart
to be latitude 24° 53′ 36″·7 N., longitude 34° 4′ 17″·9 E.
A second connexion to a base-line was made near Gebel Um Harba, where
a base had been previously measured by Mr. Villiers Stuart in the
course of his triangulation of the western part of the desert. In
this case the connexion was not made to the actual base-line, but
to another main line tied directly on to it. The data at this point
of connexion from the two triangulations afforded a useful check on
the accuracy of the work, and were as follows:—
------------------+------------------+----------------+------------
|From Mr. Stuart’s | From my |Difference.
| triangulation. | triangulation. |
+------------------+----------------+------------
Latitude N. | 23° 36′ 55″·0 | 23° 36′ 55″·6 | 0″·6
| | |
Longitude E. | 34° 30′ 38″·1 | 34° 30′ 37″·6 | 0″·5
| | |
Length of line | | |
to Dagalai beacon| 13,170·2 metres. |13,167·9 metres.|2·3 metres.
------------------+------------------+----------------+------------
=Reconnaissance for triangulation points= was carried out
simultaneously with the triangulation itself. The distance of likely
looking peaks was determined either by intersecting them from distant
stations, or by special small triangulations from short bases, and
such selection made as seemed most likely to secure well shaped
figures and a good command of surrounding country. As a rule,
the highest summits were selected as main (occupied) stations,
while all other prominent peaks and other features were fixed by
intersection from two or more main stations. The form adopted for
the main triangulation net was a series of quadrilateral figures
with diagonals, combined with centric polygons, all the angles of
the figures being generally measured. The average length of side
was about thirty-five kilometres.
=Beacons.=—Main stations were marked by wrought-iron beacons,
consisting of two lengths of stove piping about 15 centimetres
diameter by 1½ metres long, the upper length fitting into a faucet
made by splaying out the lower tube. Near the top of the tube were
affixed four sheet iron wings, bolted on to angle iron cleats. A
conical cairn of stones was built up round the tube, nearly up to the
wings, so that the beacon when erected was about three metres high,
two metres in diameter across the base of the cairn, and about a
metre wide across the wings. The beacons were taken down while a
station was being occupied, and replaced on leaving.
Intersected points were sometimes marked with a beacon or cairn,
but in general the peaks were simply bisected from several stations,
as it was found that this gave sufficiently accurate results.
=Measurement of Horizontal Angles.=—Angles were measured with a
6-inch theodolite furnished with reading microscopes graduated to
10″ and permitting of reliable estimations to 1″. The angles
between main points were read on four arcs to eliminate circle
errors. Intersected points were observed on one arc only. The average
error of closure of main triangles was 3″·3.
=Field Computation and Plotting of Triangulated Points.=—The
triangles were computed by the ordinary method, but the angles
were rounded off to 10″ to enable the sines to be taken direct
from the logarithmic tables, and the logarithms were only taken
to five places. The length of the sides having been thus found, the
geographical positions were found by the ordinary _L M Z_ computation,
using, however, only two latitude terms and 5-place logarithms,
while azimuths were only taken out to the nearest 10″. The
abbreviated form of computation used will be best illustrated by
an example:—[63]
_Computation of Position of_ △ _No. 260 from No. 275._
_l_ = 20042 m. { φ = 23° 55′ 30″·6
275 {
_Z_ = 64° 29′ 20″ E of N. { λ = 34° 54′ 36″·9
Log _l_ = 4·30194 Log _l_² = 8·604
- -
Log cos _Z_ = 1·63416 Log sin² _Z_ = 1·911
- -
_B_ 2·51194 _C_ = 9·053
------- -----
-
2·44804 = 1·568
------- -----
_d_φ, 1st term = + 280″·6 Log _l_ = 4·30194
-
2nd term = − 0″·4 Log sin _Z_ = 1·95545
-------------- -
_d_φ = 280″·2 _A′_ = 2·50948
-------
= 4′ 40″·2 = 2·76687
-
φ = 23° 55′ 30″·6 Log cos φ′ = 1·96072
-------------- -------
φ′ = 24° 0′ 10″·8 = 2·80615
-------------- -------
_d_λ = 640″·0
Whence = 10′ 40″·0
{ φ′ = 24° 0′ 10″·8 λ = 34° 54′ 36″·9
260 { --------------
{ λ′ = 35° 5′ 16″·9 λ′ = 35° 5′ 16″·9
--------------
In the above, it will be noticed that the azimuth is always noted
as so much east or west of north or south. If this convention be
adopted, one may consider the first term of _d_φ as always +,
and the second term will be + if the azimuth contains the word
south,—if it is from the north, while the total _d_φ is to be added
or subtracted according as one is going north or south. A somewhat
similar convention is adopted in neglecting the sign of _d_λ till
the actual addition or subtraction is made. It was found in the
field that this method prevented any mistake of sign, while being
much simpler to work than one involving angles greater than 90°.
The geographical coordinates thus found were plotted directly on to
the plane-table sheets, on which the graticule at 10′ intervals
was the first thing drawn. The odd minutes and seconds were first
converted into minutes and decimals, and then into kilometres by
multiplying by the factors appropriate to the latitude, so that the
plotting could be done by the ordinary scale of kilometres. To avoid
difficulties of paper-shrinkage, as many points as possible were
plotted at the time of drawing the graticule, and in general the
points had to be plotted as far ahead as possible for controlling
the traversing and sketching.
=Astronomical Observations.=—Astronomical checks on the
triangulation were obtained by observations of latitude at certain
selected main stations 60-120 kilometres apart, and by azimuth
observations for certain main lines.
The method used for =latitude= was that of observing the times of
equal altitudes of three or more stars, selected as near to the
meridian[64] as possible. This method presents great advantages
over the usual _Polaris_ and circummeridian altitudes, in that the
observations are more easily made, and yield much more accurate
results, because uncertainties in refraction are largely eliminated
and the errors of circle graduation are not involved, the altitudes
not being read at all.[65] The theodolite used was the same as
was employed in triangulation, and the times were taken by a half
chronometer watch, preferably one marking sidereal time with a rate
which could be considered negligible during the hour or so occupied
by the observation. The first star taken was usually _Polaris_, and
the vertical circle was left clamped at its altitude. For the other
stars, any dislevelment was corrected by touching up the levelling
screws just before the instant of observation; this was found better,
than taking bubble readings and correcting for slight difference
of altitude.
The method which I found best in the field for reducing
the observations differs somewhat from that described by
Chauvenet. Assuming approximate values for the latitude and watch
error, I first calculated the altitude of each star from the formula
sin _h_ = sin φ sin ε + cos φ cos δ cos _t_
If the assumed latitude and watch error were correct, all the stars
would give the same value for _h_. If not, each star would give an
equation of the form
_h_ + cos _A_ _d_φ + cos φ sin _A_ _dT_ − _h_0 = 0
where _A_ is the star’s azimuth, _d_φ the required correction
to the assumed latitude, _dT_ the required correction to the
assumed watch times, and _h_0 the true altitude common to the three
stars. The values of cos _A_ and cos φ sin _A_ were calculated from
the ordinary formula
sin _A_ = (cos δ sin _t_)/cos _h_
by four-place logarithms (using the approximate values for φ, _t_,
and _h_, since these are quite sufficiently accurate for the purpose)
and inserted into the three star-equations.[66] By then solving the
three simultaneous equations for _d_φ, the required correction to
the assumed latitude was at once obtained.
As the method is one not usually treated of in books on practical
astronomy, I give on the following pages the reduction of an
observation worked out in full.
_Latitude by Equal Altitudes of Three Stars._
Station on Gebel Um Heshenib. January 30, 1906.
Approximate φ = 24° 20′ 50″ N.
„ λ = 34° 51′ 0″ E.
Sidereal watch U. and C. 30811, approximately 2m 22s fast on L.S.T.,
rate negligible.
Observed times of equal altitudes by watch:—
_Polaris_ 3h 33m 54s·2
α _Columbæ_ 3 42 40 ·8
ε _Canis majoris_ 4 24 35 ·8
_Polaris._
Watch time 3h 33m 54s·2
Watch fast 2 22 ·0
------------
L.S.T. 3 31 32 ·2
Star’s R.A. 1 25 9 ·1
------------
_t_ 2 6 23 ·1 = 31° 35′ 46″·5 W. of meridian.
------------
-
φ = 24° 20′ 50″ log sin 1·6151769
-
δ = 88° 48′ 33″·1 log sin 1·9999062
---------
- -
1·6150831 log cos δ 2·3177
-
Nat. (1) 0·4121764 log sin _t_ 1·7193
--------- ------
-
2·0370
- -
φ = 24° 20′ 50″ log cos 1·9595488 log cos _h_ 1·9560
------
- -
δ = 88° 48′ 33″·1 log cos 2·3176870 log sin _A_ 2·0810
- -
_t_ = 31° 35′ 46″·5 log cos 1·9303179 log cos φ 1·9595
--------- ------
-
2·0405
- -
2·2075537 Nat. = 0·011
---------
Nat. (2) 0·0161270
Nat. (1) 0·4121764 log cos _A_ 1·9999
---------
0·4283034 Nat. = 1·000
-
log sin _h_ 1·6317515
_h_ = 25° 21′ 35″·8
Whence the equation for _Polaris_ is
35·8 + 1·000 _d_φ − 0·011 _dT_ − _h_0 = 0 (1)
α _Columbæ._
Watch time 3h 42m 40s·8
Watch fast 2 22 ·0
------------
L.S.T. 3 40 18 ·8
Star’s R.A. 5 36 15 ·6
------------
_t_ 1 55 56 ·8 = 28° 59′ 12″·0 E. of meridian.
------------
-
φ = 24° 20′ 50″ log sin 1·6151769
-
δ = 34° 7′ 45″·7 log sin 1·7490118
---------
-
1·3641887
-
Nat. (1) 0·2313070 log cos δ 1·9179
--------- -
log sin _t_ 1·6854
------
- -
φ = 24° 20′ 50″ log cos 1·9595488 1·6033
- -
δ = 34° 7′ 45″·7 log cos 1·9179112 log cos _h_ 1·9560
------
- -
_t_ = 28° 59′ 12″·0 log cos 1·9418753 log sin _A_ 1·6473
---------
- -
1·8193353 log cos φ 1·9595
--------- ------
Nat. (2) 0·6596830 1·6068
Nat. (1) 0·2313070 Nat. = 0·404
---------
0·4283760
- -
log sin _h_ 1·6318196 log cos _A_ 1·9523
Nat. = 0·896
_h_ = 25° 21′ 51″·1
Whence the equation for α _Columbæ_ is
51·1 − 0·896 _d_φ + 0·404 _dT_ − _h_0 = 0 (2)
ε _Canis majoris._
Watch time 4h 24m 35s·8
Watch fast 2 22 ·0
------------
4 22 13 ·8
Star’s R.A. 6 54 57 ·1
------------
_t_ 2 32 43 ·3 = 38° 10′ 49″·5 E. of meridian.
------------
-
φ = 24° 20′ 50″ log sin 1·6151769
-
δ = 28° 50′ 52″·7 log sin 1·6834857
---------
-
1·2986626
Nat. (1) 0·1989128
---------
-
φ = 24° 20′ 50″ log cos 1·9595488
- -
δ = 28° 50′ 52″·7 log cos 1·9424561 log cos δ 1·9424
- -
_t_ = 38° 10′ 49″·5 log cos 1·8954602 log sin _t_ 1·7911
--------- ------
- -
1·7974651 1·7335
--------- -
Nat. (2) 0·6272853 log cos _h_ 1·9560
------
-
Nat. (1) 0·1989128 log sin _A_ 1·7775
--------- -
0·4283725 log cos φ 1·9595
- ------
log sin _h_ 1·6318215 1·7370
Nat. = 0·546
_h_ = 25° 21′ 51″·5
-
log cos _A_ 1·9034
Nat. = 0·801
Whence the equation for ε _Canis majoris_ is
51·5 − 0·801 _d_φ + 0·546 _dT_ − _h_0 = 0 (3)
Collecting the equations of the three stars, we have
35·8 + 1·000 _d_φ − 0·011 _dT_ − _h_0 = 0 (1)
51·1 − 0·896 _d_φ + 0·404 _dT_ − _h_0 = 0 (2)
51·5 − 0·801 _d_φ + 0·546 _dT_ − _h_0 = 0 (3)
By solving these equations for _d_φ, we find
_d_φ = + 6″·5
whence the latitude is found to be
24° 20′ 56″·5
It may be remarked that the above process was considerably shortened
when it was possible to get a pair of observations on the same south
star both east and west of the meridian, instead of on two separate
south stars. In that case the watch error was found at once from the
difference between the star’s R.A. and the mean of the two observed
times, and the latitude could be found from two equations instead of
three. The condition for this modification of the method was that
a nautical almanac star could be found culminating at an altitude
slightly greater than that of _Polaris_ at a time convenient for the
observation. It is not advisable to select a star which would give too
long an interval between the equal east and west altitudes. The best
results are obtainable when the interval between the two observations
of the south star is about an hour, and when _Polaris_ is near its
transit. Under such circumstances the watch correction is obtained
quite nearly enough for a good latitude; for, as Gauss[67] pointed
out, “the essential condition is not so much that the precise
instant when the star reaches a supposed place should be noted,
as that at the time which is noted the star should not be sensibly
distant from that place.”
The following table shows the latitudes found by observation and
triangulation at the various points. It may be remarked that the
method used for latitude determination was liable to observational
errors of 2″ or so, as well as to errors of possibly more
than double that amount due to plumb-line deflection among the
mountains,[68] so that the observed latitudes were only taken as
checks to prevent any gross error in triangulation being overlooked,
and not for any determination of the figure of the earth, for which
latter purpose more elaborate observations would have been necessary.
--------------------+--------------+--------------+-------------------
|Lat. observed.|Lat. computed | Difference
Point. | | from |computed-observed.
| |Triangulation.|
--------------------+--------------+--------------+-------------------
West Peg, Muelih |24° 53′ 40″·3 |24° 53′ 36″·7 | − 3″·6
Base | | |
| | |
Beacon on Gebel Um |24° 20′ 56″·5 |24° 20′ 49″·2 | − 7″·3
Heshenib | | |
| | |
„ „ Hill near|23° 55′ 33″·2 |23° 55′ 30″·6 | − 2″·6
Gebel Selaia | | |
| | |
„ „ Berenice |23° 54′ 39″·5 |23° 54′ 40″·3 | − 0″·8
Temple | | |
| | |
„ „ Gimeida |22° 46′ 33″·2 |22° 46′ 29″·4 | − 3″·8
Hill | | |
--------------------+--------------+--------------+-------------------
=Azimuths= were determined in the usual manner[69] by elongations
of close circumpolar stars, _Polaris_ or _51 Cephei_ being usually
selected. The azimuth mark used was an ordinary Egyptian _shamadan_
(candlestick with spring feed) with a glass globe, placed at a
distance of one to two kilometres, with its foot firmly bedded in
sand and stones to prevent any motion. The azimuths observed at the
different stations are shown in the following table:—
------------------------+----------------------+---------------------
Station of Observation.| Point to which | Azimuth observed.
| Azimuth is given. |
------------------------+----------------------+---------------------
Peg at West end of |Peg east end of base |33° 30′ 6″ E. of N.
Muelih Base | |
| |
Beacon on Gebel Um |Beacon on Gebel Hamata|45° 15′ 34″ E. of S.
Heshenib | |
| |
„ „ Hill near | „ „ Abu Gurdi |25° 30′ 35″ N. of E.
Gebel Selaia | |
| |
„ „ Berenice | „ „ Kalalat |61° 10′ 31″ W. of S.
Temple | |
| |
„ „ Gimeida Hill | „ „ Hamra Dom | 6° 14′ 46″ E. of S.
| |
| |
Centre of Halaib Fort | „ „ Elba |83° 25′ 0″ W. of S.
------------------------+----------------------+---------------------
The observed azimuths, unlike the observed latitudes, were more
accurate than the results of triangulation, repetition having shown
them to be reliable within 2″ or 3″, an error of which magnitude
would soon be surpassed in the process of continuing a chain of
azimuths with the unadjusted values of the angles of the triangles,
which were the only values possible to be used in the field. On
arriving at an azimuth station, therefore, a fresh chain of azimuths
was begun from the results of the observation, and continued to the
next station where astronomical observations were undertaken. The
accumulated azimuth error was, however, never found to exceed 10″
in any chain, a quantity which could not sensibly affect the computed
positions of points for plotting on the maps.
=Connexion with the Sudan Surveys.=—At the south end of the
area, connexion was made to a number of points triangulated by
the Sudan Surveys, but as the Sudan triangulation was commenced
as an independent piece of work from an observed latitude and a
telegraphically determined longitude, the connexion affords no
check on the accuracy of the triangulations. The difference found
between my positions and those of the Sudan Surveys was practically
constant for all the Sudan points connected, and amounted to 3″·5
in latitude and 26″ in longitude[70]; these figures represent the
errors in the assumed latitude and longitude of the starting point
of the Sudan Surveys, and will be employed as corrections to the
Sudan positions now that a complete chain of triangulation connects
Berber with the Mediterranean.
=Levels of Triangulation Points.=—The altitudes above sea-level
of all triangulation points were determined by vertical angular
measurements carried out at the occupied stations, an actual sea-level
datum being obtained by including rocks awash in the sea among the
triangulated points. To secure constancy of atmospheric refraction
as far as possible, vertical angles were always read in the middle of
the day, where the change of refraction is slowest. For the occupied
stations, refraction and curvature were eliminated by reciprocal
observations. For intersected points the formula _h_ = _d_ _tan_
θ + (1 − _k_)/2_r_ _d_² was used, the value of _d_ tan θ being
first found by five-figure logarithms and then that of the curvature
and refraction correction (1 − _k_)/2_r_ _d_² by means of the very
convenient “Universal” slide rule of Nessler.[71] The value of _k_
found from a discussion of the first few reciprocal observations was
found to be very nearly 0·13, corresponding with the mean of European
determinations, and this value for the coefficient was employed
throughout the work for intersected points.[72] For obtaining the
correction (1 − _k_)/2_r_ _d_² by the slide rule, a mark _R_ was
scratched at 1210[73] on the lower scale of the slide; by bringing
this mark _R_ opposite to the distance (in kilometres) on the lower
scale (or, where the logarithm of the distance was more convenient,
by bringing the mark vertically under that logarithm on the log scale
of the rule by means of the cursor) the correction could be read off
directly on the lowest fixed scale opposite the end-graduation of
the slide. Usually four or five values for the altitude of a single
point were obtained from a corresponding number of stations, and
the mean taken; the various values generally agreed within two metres.
The constant combination of vertical angular measurements with
horizontal ones was of great service from another point of view
from that of providing altitude data for the maps. It frequently
happened that a peak observed at one station could not be identified
among a number of similar peaks visible at another station. When
this trouble arose, the vertical angles offered a way out of
the difficulty. Vertical and horizontal angles were read off to
a number of likely-looking peaks; on working out the triangles to
the nearest minute of the observed angles, the distance of each peak
was obtained on the assumption that it was the one required. Then to
find which of the several peaks was the correct one, the elevations
were worked out, assuming the distances correct; in only one case
would the level agree from the two stations, and this obviously
discriminated the peak required. The working out of the triangles
for this purpose could be done with sufficient accuracy in a very
few minutes by means of the slide rule, and many points were thus
saved from rejection consequent on misidentification.
Checks on absolute level were frequently obtained by observing
depression angles to the sea horizon, using the formula θ = 107·8
√{_h_}, where θ is in seconds of arc and _h_ is the altitude in
metres. But for high stations the horizon is so distant that very
small variations in refraction cause rather large errors in the
result, so that this method only furnished a rough check.
=Summary of Triangulated Positions.=
The following tables give the geographical positions and altitudes
above sea-level of all points triangulated, arranged in order of
diminishing latitude, _i.e._, from north to south. The list includes
the points fixed within the Sudan for connexion with the Sudan
Surveys. Stations occupied are indicated by an asterisk against the
number of the point. It will be noticed that in some cases several
different mountains bear the same name though widely distant from
each other; also that where a single mountain mass possesses several
peaks or summits, each of these has been fixed separately.
SUMMARY OF TRIANGULATED POSITIONS.
--------+--------------------+-----------+--------+---------+---------
Field | | | | |
Number| Name. | Mark. |Latitude|Longitude|Altitude
of | | | N. | E. | Metres.
Point.| | | | |
--------+--------------------+-----------+--------+---------+---------
| | | ° ′ ″| ° ′ ″ |
| | | | |
21 |G. Hamrat Wogud | cairn. |25 9 34|34 20 0 | 1,103
| | | | |
29 |G. Iteima | „ |25 8 1|34 11 13 | 849
| | | | |
* 204 |G. Igli | „ |25 4 6|34 36 16 | 975
| | | | |
* 26a|G. Atut | „ |25 0 56|34 23 49 | 908
| | | | |
* 203 |Erf el Fahid | „ |25 0 5|34 11 52 | 579
| | | | |
14 |G. Hagar Dungash | „ |24 59 12|34 2 33 | 815
| | | | |
* 218 |G. Sukari | „ |24 56 50|34 42 50 | 476
| | | | |
216 |G. Um Tundeba | summit. |24 55 48|34 47 29 | 550
| | | | |
* 202 |Muelih base | E. peg. |24 54 44|34 5 7 | 406
| | | | |
219 |Isolated hill near | summit. |24 54 23|34 54 21 | 190
|sea | | | |
| | | | |
* 201 |Muelih base | W. peg. |24 53 37|34 4 18 | 398
| | | | |
19 |G. Muelih | cairn. |24 52 44|34 0 37 | 707
| | | | |
* 225 |Kurdeman mines | „ |24 52 35|34 41 35 | 525
| | | | |
71 |Marwot Rod el Ligah | „ |21 51 31|34 8 21 | 514
| | | | |
206 |G. Mudergeg | summit. |24 51 0|34 22 1 | 885
| | | | |
205 |G. Hangalia | „ |24 50 29|34 38 43 | 1,241
| | | | |
* 215 |G. Ghadir | cairn. |24 50 9|34 47 22 | 636
| | | | |
* 32a|G. Nugrus | „ |24 48 34|34 35 47 | 1,505
| | | | |
* 25 |G. Migif | „ |24 47 23|34 27 30 | 1,199
| | | | |
* 214 |G. Allawi | „ |24 46 42|34 49 39 | 515
| | | | |
211 |G. Zabara | „ |24 45 21|34 41 53 | 1,361
| | | | |
224 |G. Lewewi | „ |24 44 38|34 46 39 | 654
| | | | |
212 |Ridge near G. Zabara| N. end. |24 43 48|34 40 56 | 1,104
| | | | |
221 |Hill near sea | summit. |24 42 31| 35 3 15 | —
| | | | |
208 |G. Hamrat Selma | „ |24 41 58|34 20 58 | 761
| | | | |
210 |Peak in G. Hafafit | cairn. |24 40 44|34 37 8 | 722
| | | | |
240 |Wadi Gemal island | N. end. |24 40 45|35 9 6 | 0
| | | | |
* 223 |G. Sikait | cairn. |24 39 55|34 48 5 | 771
| | | | |
213 |G. Um Moghar | summit. |24 39 16|34 41 5 | 860
| | | | |
24a|G. Abu Khrug | cairn. |24 38 57|34 16 19 | 870
| | | | |
20 |G. Sufra | beacon. |24 38 42|34 4 13 | 690
| | | | |
241 |Wadi Gemal island | S. end. |24 38 38|35 10 36 | 0
| | | | |
207 |G. Nahud | N. cone. |24 35 36|34 22 14 | 662
| | | | |
* 209 |Peak in G. Hafafit | beacon. |24 35 32|34 45 22 | 744
| | | | |
* 222 |Madaret Um Gamil | „ |24 34 52|34 56 28 | 454
| | | | |
226 |G. Abu Had | summit. |24 34 12|34 36 6 | 633
| | | | |
242 |Low spur of coast | tip. |24 33 47|35 10 2 | 0
| | | | |
235 |G. Um Regeba | summit. |24 33 36|34 42 29 | 571
| | | | |
233 |G. Nahud | S. cone. |24 33 35|34 20 11 | 662
| | | | |
239 |Low spur of coast | tip. |24 28 43|35 10 58 | 0
| | | | |
247 |G. Um Suerab | summit. |24 26 50|34 42 33 | 1,024
| | | | |
231 |G. Um Sueh | „ |24 26 45|34 54 30 | 781
| | | | |
236 |G. el Abiad | „ |24 26 27|34 48 56 | 892
| | | | |
* 227 |G. Abu Hegilig | „ |24 26 16|34 58 32 | 607
| | | | |
237 |G. Um el Abbas | „ |24 26 11|34 56 33 | 697
| | | | |
232 |G. Nukheira | „ |24 25 58|34 32 53 | 876
| | | | |
73 |G. Um Goraf | cairn. |24 25 33|34 18 28 | —
| | | | |
252 |G. Durunkat | centre. |24 23 43|34 45 51 | 924
| | | | |
274 |S. end of low sandy | — |24 22 41|35 22 56 | 0
|island | | | |
| | | | |
255 |G. Um Sedri |S. peak of |24 22 0|34 41 3 | 970
| | twin. | | |
| | | | |
234 |G. el Heda | summit. |24 20 56|34 30 11 | 862
| | | | |
248 |G. Sarobi (S. peak) | „ |24 20 50|35 9 0 | 471
| | | | |
* 228 |G. Um Heshenib | beacon. |24 20 49|34 50 53 | 1,135
| | | | |
243 |G. Hefeiri | summit. |24 20 22|35 1 21 | 612
| | | | |
246 |G. Khulla | „ |24 19 43|34 38 42 | 978
| | | | |
253 |G. Tarfawi | N. end of |24 18 46|34 55 54 | 1,363
| | ridge. | | |
| | | | |
251 |G. Marasan | summit. |24 17 34|34 44 56 | 1,261
| | | | |
249 |G. Abu Ghusun | „ |24 16 1|34 58 17 | 1,389
| | | | |
245 |G. Metawit | „ |24 15 51|34 31 48 | 741
| | | | |
* 230 |G. Abu Hamamid | beacon. |24 14 41|34 47 38 | 1,747
| | | | |
250 |G. Um Usher | summit. |24 14 11|34 53 21 | 1,487
| | | | |
259 |G. Um Hasidok | „ |24 12 45|34 54 46 | 1,497
| | | | |
* 229 |G. Hamata | beacon. |24 12 17|35 0 16 | 1,978
| | | | |
258 |G. Abarun | summit. |24 11 20|34 50 18 | 1,602
| | | | |
257 |G. Abu Argub | „ |24 11 1|34 45 43 | 1,609
| | | | |
75 |G. Hamrat Mukbud | cairn. |24 9 53|34 23 17 | 890
| | | | |
254 |G. Ras el Kharit | peak. |24 9 25|35 1 55 | 1,661
| | | | |
261 |G. Khashir | summit. |24 9 14|35 4 50 | 1,565
| | | | |
262 |G. Ras el Kharit | peak. |24 9 2|35 0 28 | 1,564
| | | | |
* 256 |G. Kahfa | beacon. |24 8 18|34 38 55 | 1,018
| | | | |
* 399 |Hill near Bir Qoleib| beacon. |24 8 6|33 42 46 | 355
| | | | |
400 |Bir Qoleib |clay basin.|24 6 36|33 41 20 | 239
| | | | |
287 |G. el Anbat | summit. |24 5 12|34 54 58 | 788
| | | | |
263 |G. Mikbi | S. end of |24 4 54|35 4 49 | 1,388
| | ridge. | | |
| | | | |
276 |G. Um Huk | cairn. |24 4 41|35 15 34 | 517
| | | | |
279 |G. Um Sellim | E. peak. |24 3 52|35 9 51 | 947
| | | | |
320 |Peak N. of Berenice | summit. |24 3 41 |35 26 30 | 276
| | | | |
264 |G. Egat | peak. |24 3 40 | 35 3 32 | 1,277
| | | | |
273 |G. Egat | summit. |24 2 52 | 35 2 29 | 1,422
| | | | |
280 |G. Abu Ghalqa | cairn. | 24 1 7 |35 16 47 | 561
| | | | |
* 260 |G. Abu Gurdi | beacon. |24 0 11 | 35 5 17 | 1,562
| | | | |
288 |G. Derhib | summit. | 24 0 8 | 35 1 29 | 1,160
| | | | |
* 315 |Hill near Berenice | beacon. | 24 0 4 |35 30 37 | 196
| | | | |
268 |G. el Homur | summit. |23 58 54|34 55 16 | 731
| | | | |
289 |G. Um Gunud | cairn. |23 57 46|35 12 10 | 989
| | | | |
* 339 |Limestone hill on | beacon. |23 57 16|35 43 10 | 187
|Ras Benas | | | |
| | | | |
271 |G. Selaia | summit. |23 57 14|34 52 13 | 787
| | | | |
* 317 |Hill on Ras Benas | beacon. |23 56 40|35 39 44 | 193
| | | | |
* 316 |Limestone peak, Ras | „ |23 56 36| 35 36 9 | 189
|Benas | | | |
| | | | |
* 338 |Hill on Ras Benas | cairn. |23 56 1 |35 40 53 | 197
| | | | |
291 |G. Aidab | summit. |23 55 52|35 13 38 | 848
| | | | |
270 |Hill near G. Selaia | „ |23 55 46|34 53 58 | 623
| | | | |
* 275 |Low hill near G. | beacon. |23 55 30|34 54 37 | 563
|Selaia | | | |
| | | | |
278 |G. Geneina | peak near |23 54 56|34 47 45 | 548
| | N. end. | | |
| | | | |
336 |G. Um Maiat | N. end. |23 54 45|35 13 35 | 928
| | | | |
* 313 |Berenice Temple | beacon. |23 54 39|35 28 26 | 8
| | | | |
290 |Marwot Elemikan | summit. |23 54 14| 35 6 8 | 648
| | | | |
319 |Peak N. of G. | „ |23 54 10|35 13 55 | 870
|Kalalat | | | |
| | | | |
334 |Hill near Wadi | „ |23 53 57| 35 22 0 | —
|Mindeit | | | |
| | | | |
340 |Sheikh’s tomb at | centre. |23 53 50|35 47 13 | 3
|Ras Benas | | | |
| | | | |
341 |Tip of Ras Benas | sandy |23 53 42| 35 47 5 | 0
| | point. | | |
| | | | |
266 |G. Abu Derega | summit. |23 53 38|34 59 13 | 831
| | | | |
335 |G. Um Maiat | S. end. |23 53 34|35 14 48 | 842
| | | | |
333 |High range N. of G. | N. end. |23 53 3 | 35 15 1 | 875
|Kalalat | | | |
| | | | |
77 |G. el Nekeiba | cairn. |23 52 34|34 22 10 | 570
| | | | |
330 |Hill near Wadi | summit. |23 52 29|35 22 18 | 328
|Kalalat | | | |
| | | | |
318 |G. Um Maiat | central |23 52 24|35 15 36 | 821
| | peak. | | |
| | | | |
332 |High range N. of G. | S. end. |23 51 59|35 16 29 | 762
|Kalalat | | | |
| | | | |
331 |G. Kalalat |minor peak.|23 50 48|35 15 51 | 743
| | | | |
294 |N. end of Mukawar | — |23 50 47|35 48 31 | 0
|Island | | | |
| | | | |
293 |G. Batoga | central |23 50 7 |35 20 46 | 802
| | peak. | | |
| | | | |
329 |G. Kalalat | N. peak. |23 49 57| 35 17 6 | 1,080
| | | | |
294a|S. end of Mukawar | — |23 49 53|35 48 19 | 0
|Island | | | |
| | | | |
314 |G. Batoga (S. peak) | beacon. |23 49 37| 35 21 9 | 785
| | | | |
* 282 |G. Kalalat | „ |23 49 9 |35 17 36 | 1,125
| | | | |
328 |G. Batoga |minor peak.|23 48 57|35 22 47 | 413
| | | | |
353 |Minor peak of G. | S. one of |23 47 37|35 18 46 | 894
|Kalalat | pair. | | |
| | | | |
355 |G. Um Hegilig | summit. |23 47 13|35 14 32 | 966
| | | | |
327 |G. Dibag | NW. peak. |23 46 47|35 21 23 | 517
| | | | |
308 |G. Dibag | SE. peak. |23 46 40| 35 22 4 | 544
| | | | |
* 265 |G. Dahanib | beacon. |23 45 44|35 11 10 | 1,270
| | | | |
* 269 |G. Um Bisella | „ |23 45 34|34 57 39 | 824
| | | | |
* 277 |G. Zergat Naam | „ |23 45 28|34 40 34 | 823
| | | | |
345 |G. Reyan | N. peak. |23 45 20|35 17 50 | 740
| | | | |
346 |G. Reyan | S. peak. |23 44 7 |35 17 20 | 863
| | | | |
* 343 |Hill near Shenshef | beacon. |23 44 5 |35 22 40 | 290
|ruins | | | |
| | | | |
292 |Erf el Gemal | W. end of |23 43 37|34 52 10 | 673
| | ridge. | | |
| | | | |
272 |G. Hagar el Fil | summit. |23 43 5 | 34 42 3 | 845
| | | | |
281 |G. Shut | „ |23 42 35|35 16 59 | 930
| | | | |
398 |Bir Abu Hashim | principal |23 41 56| 34 4 26 | 320
| | well. | | |
| | | | |
* 397 |Hill near Bir Abu | beacon. |23 41 44| 34 3 33 | 386
|Hashim | | | |
| | | | |
348 |Hill near W. Salib | summit. |23 41 5 | 35 7 3 | 703
|Abiad | | | |
| | | | |
325 |G. Um Etli | central |23 39 54|35 23 22 | 795
| | peak. | | |
| | | | |
384 |G. Abu Husenat | summit. |23 39 45| 35 1 15 | 725
| | | | |
326 |G. Um Etli | W. peak. |23 39 32|35 21 52 | 844
| | | | |
324 |G. Um Etli | E. peak. |23 39 26|35 23 53 | 764
| | | | |
295 |G. Hendusi |sharp peak.|23 39 15|34 58 44 | 678
| | | | |
344 |G. Um Akra | beacon. |23 37 58|35 16 41 | 1,050
| | | | |
* 385 |Ruins of Um Eleiga | „ |23 37 20| 35 3 5 | 599
| | | | |
302 |Peak near G. Abu | summit. |23 37 16| 35 6 44 | 840
|Dahr | | | |
| | | | |
* 79 |Um Harba | beacon. |23 36 56|34 30 38 | 688
| | | | |
356 |G. Um Akra | S. peak. |23 36 35|35 16 58 | 970
| | | | |
347 |G. Hindia | summit. |23 36 27|35 13 39 | 873
| | | | |
337 |Zeberged Island | central |23 36 16|36 11 42 | 238
| | peak. | | |
| | | | |
* 267a|G. Abu Dahr | beacon. |23 36 8 | 35 5 46 | 1,131
| | | | |
305 |G. Abu Sieiyil | summit. |23 35 16| 35 1 4 | 833
| | | | |
321 |G. Faraid | peak. |23 34 8 |35 23 18 | 1,131
| | | | |
323 |G. Faraid | „ |23 33 29|35 21 50 | 1,341
| | | | |
361 |Hill S. of G. Abu | summit. |23 33 28| 35 4 42 | 912
|Dahr | | | |
| | | | |
322 |G. Faraid | highest |23 33 7 |35 22 10 | 1,366
| | peak. | | |
| | | | |
342 |G. Faraid | „ |23 31 53|35 22 46 | 1,068
| | | | |
360 |Hill S. of G. Abu | summit. |23 31 43| 35 5 15 | 772
|Dahr | | | |
| | | | |
362 |Hill S. of G. Abu | „ |23 31 37| 35 2 49 | 793
|Dahr | | | |
| | | | |
359 |Hill S. of G. Abu | „ |23 31 17| 35 6 22 | 784
|Dahr | | | |
| | | | |
* 285 |G. Faraid | peak. |23 30 53|35 20 25 | 1,259
| | | | |
* 85 |G. Um Khafur | beacon. |23 29 54|34 29 19 | 560
| | | | |
357 |G. Faraid |minor peak.|23 29 35|35 17 30 | 862
| | | | |
286 |G. Faraid | “The |23 28 58|35 20 35 | 1,232
| | Bodkin.” | | |
| | | | |
350 |G. Faraid | outlying |23 28 39|35 17 35 | 875
| | peak. | | |
| | | | |
351 |G. Faraid | peak. |23 28 35|35 16 31 | 954
| | | | |
352 |Granite peak near | summit. |23 27 48|35 13 15 | 697
|Wadi Rahaba | | | |
| | | | |
349 |G. Faraid | outlying |23 27 14| 35 19 5 | 904
| | peak. | | |
| | | | |
297 |G. Orga | beacon. |23 26 21| 35 8 17 | 682
| | | | |
363 |Hill near Wadi | summit. |23 26 18|35 12 38 | 506
|Rahaba | | | |
| | | | |
* 296 |G. Abraq | beacon. |23 25 19|34 46 48 | 667
| | | | |
365 |Hill near Wadi | summit. |23 25 2 |35 11 42 | 536
|Rahaba | | | |
| | | | |
389 |G. Faraid |minor peak.|23 24 57|35 24 42 | 585
| | | | |
358 |G. Faraid | peak. |23 22 39|35 22 19 | 916
| | | | |
395a|G. Abraq | „ |23 22 26|34 50 18 | 699
| | | | |
395 |G. Abraq | „ |23 22 19| 34 50 4 | 705
| | | | |
* 87 |G. Awamtib | beacon. |23 20 59|34 26 39 | 793
| | | | |
* 299 |G. Um Tenedba | „ |23 19 48|35 10 40 | 656
| | | | |
368 |Hill near G. Um | summit. |23 18 43|35 12 36 | 555
|Tenedba | | | |
| | | | |
* 390 |Plateau near Abu | beacon. |23 18 40|34 48 30 | 639
|Saafa | | | |
| | | | |
307 |G. Saalek | peak E. |23 18 18|34 31 10 | 753
| | side. | | |
| | | | |
* 354a|G. Fereyid | beacon. |23 17 29|35 22 48 | 612
| | | | |
394 |G. Hodein | „ |23 16 20|34 53 25 | 695
| | | | |
380 |G. Hodein | corner of |23 16 18|34 52 5 | 718
| | scarp. | | |
| | | | |
304 |Peak W. of G. Um | summit. |23 15 26|34 30 14 | 805
|Reit | | | |
| | | | |
306 |Peak W. of G. Um | „ |23 15 23|34 31 47 | 837
|Reit | | | |
| | | | |
366 |Hill near Wadi | „ |23 15 4|35 16 25 | 420
|Rahaba | | | |
| | | | |
* 300 |G. Um Reit | beacon. |23 15 4|34 34 17 | 857
| | | | |
* 298a|G. Harhagit | „ |23 14 35|35 12 52 | 542
| | | | |
393 |G. Tibatib | summit. |23 12 41|35 1 28 | 396
| | | | |
387 |Hill near Wadi | „ |23 12 24|35 16 51 | 383
|Hodein | | | |
| | | | |
396 |Granite peak near | „ |23 11 11|35 20 35 | 355
|Wadi Rahaba | | | |
| | | | |
392 |Rock in sea | (level |23 10 55|35 35 57 | 0
| | datum). | | |
| | | | |
310 |Isolated hill west | summit. |23 10 35|34 25 23 | 703
|of G. Etresia | | | |
| | | | |
388 |Hill near Wadi | „ |23 10 33|35 16 32 | 309
|Hodein | | | |
| | | | |
423 |G. Kala | „ |23 10 3|34 45 49 | 808
| | | | |
503 |G. Etresia |E. summit. |23 9 24|34 30 43 | 1,037
| | | | |
303 |Hill E. of G. | summit. |23 9 15|34 32 23 | 922
|Etresia | | | |
| | | | |
* 375a|G. Anfeib | beacon. |23 8 24|34 59 19 | 705
| | | | |
364 |Hill NE. of G. el | summit. |23 8 0|35 21 46 | 359
|Anbat | | | |
| | | | |
* 386 |Close to Bir | beacon. |23 7 57|35 36 23 | 13
|Shalatein | | | |
| | | | |
502 |G. Etresia | summit. |23 7 53|34 31 24 | 1,038
| | | | |
407 |G. Kala | „ |23 7 42|34 42 58 | 846
| | | | |
311 |Isolated hill north | „ |23 7 16|34 24 39 | 901
|of G. Shigigat | | | |
| | | | |
425 |G. Kala | „ |23 7 11|34 42 37 | 783
| | | | |
424 |G. Kala | „ |23 6 51|34 42 30 | 739
| | | | |
501 |G. Etus | „ |23 6 19|34 29 53 | 997
| | | | |
* 367a|G. el Anbat | beacon. |23 6 5|35 19 27 | 390
| | | | |
312 |G. Shigigat |conspicuous|23 5 37 |34 23 39 | 1,023
| | peak. | | |
| | | | |
406 |G. Kala | summit. |23 5 16|34 42 19 | 629
| | | | |
500 |G. Aqab el Negum | „ |23 3 26|34 27 20 | 1,149
| | | | |
496 |G. Natetiai | peak. |23 3 8|34 21 0 | 1,022
| | | | |
499 |Peak near Aqab el | summit. |23 2 43|34 26 3 | 998
|Negum | | | |
| | | | |
498 |Peak near Aqab el | „ |23 2 22|34 25 36 | 979
|Negum | | | |
| | | | |
497 |Peak near Aqab el | „ |23 1 56|34 25 42 | 974
|Negum | | | |
| | | | |
495 |G. Natetiai | peak. |23 0 49|34 22 7 | 1,164
| | | | |
373 |G. Niqrub el Tahtani| high |23 0 42|35 0 58 | 828
| | pinnacle. | | |
| | | | |
373a|G. Niqrub el Tahtani| beacon. |23 0 39|35 0 53 | 829
| | | | |
* 369a|G. Beida | „ |23 0 14|35 16 54 | 716
| | | | |
494 |G. Natetiai | peak. |22 59 35|34 22 22 | 977
| | | | |
508 |Peak in S. part of | summit. |22 58 45|34 20 29 | 885
|G. Feg | | | |
| | | | |
391 |G. Humariai | „ |22 58 38|35 9 36 | 563
| | | | |
382 |Hill S. of Wadi | „ |22 58 10|35 12 58 | 631
|Beida | | | |
| | | | |
507 |Peak in S. part of | „ |22 58 2|34 19 15 | 836
|G. Feg | | | |
| | | | |
381a|Hill S. of Wadi | „ |22 57 30|35 16 53 | 631
|Beida | | | |
| | | | |
379 |G. Mismih | „ |22 56 56|34 45 32 | 599
| | | | |
381 |Hill S. of Wadi | „ |22 56 47|35 17 3 | 615
|Beida | | | |
| | | | |
510 |Conical hill | „ |22 54 48|34 40 27 | 504
| | | | |
* 401 |G. Kolaiqo | beacon. |22 54 13|35 24 35 | 320
| | | | |
* 374 |G. Niqrub el Foqani | „ |22 51 29|34 56 49 | 1,078
| | | | |
509 |G. Waqif | summit. |22 51 21|34 38 57 | 556
| | | | |
466 |Tree at Mersa Shab | centre. |22 50 56|35 47 3 | 1
| | | | |
419 |G. Um el Kalala | N. peak. |22 50 23|34 44 14 | 672
| | | | |
506 |G. Sheyenit | „ |22 50 13|34 18 23 | 853
| | | | |
505 |G. Sheyenit | S. peak. |22 49 58|34 18 15 | 887
| | | | |
415 |G. Um el Kalala | „ |22 49 26|34 44 18 | 655
| | | | |
418 |Hill close to Bir | beacon. |22 47 46|35 1 39 | 556
|Madi | | | |
| | | | |
* 408 |G. Meneiga | „ |22 47 35|35 11 7 | 1,032
| | | | |
* 402 |G. Meneiga | highest |22 47 31|35 10 57 | 1,092
| | point. | | |
| | | | |
430 |Hill near Wadi | summit. |22 46 29|35 20 11 | 443
|Tikosha | | | |
| | | | |
* 410 |Gemeida hill | beacon. |22 46 29|35 37 49 | 123
| | | | |
437 |Hill SSE. of Bir | summit. |22 45 58|35 13 3 | 987
|Meneiga | | | |
| | | | |
434 |Peak near Wadi Ti | „ |22 44 36|35 17 54 | 774
|Ilak | | | |
| | | | |
376 |G. Shabih | highest |22 44 26|34 50 21 | 1,117
| | peak. | | |
| | | | |
527 |G. Mishbih |NW. summit.|22 44 21|34 41 23 | 1,321
| | | | |
378 |G. Mishbih | beacon. |22 44 18|34 41 20 | 1,316
| | | | |
440 |Ridge near head of |high point.|22 44 15|35 12 18 | 1,092
|W. Shellal el Gharbi| | | |
| | | | |
447 |Qrein Salama | summit. |22 44 5|35 24 32 | 354
| | | | |
435 |Peak near Wadi Ti | „ |22 44 4|35 17 46 | 849
|Ilak | | | |
| | | | |
431 |Hill N. of Wadi | „ |22 43 55|35 18 52 | 670
|Muqur | | | |
| | | | |
414 |G. el Naga | smaller |22 43 32|34 27 22 | 747
| | hill. | | |
| | | | |
91 |G. Seiga | cairn. |22 43 31|34 16 16 | 905
| | | | |
377 |G. Mishbih | E. peak. |22 43 28|34 42 39 | 1,311
| | | | |
526 |G. Mishbih | peak. |22 42 52|34 41 27 | 1,353
| | | | |
413 |G. el Naga | N. peak. |22 42 42|34 27 46 | 787
| | | | |
445 |G. Tueiwi | summit. |22 42 40|35 5 56 | 836
| | | | |
* 403 |G. Gerf |high point |22 42 15|35 11 43 | 1,339
| | on ridge | | |
| | | | |
427 |G. Gerf | minor |22 42 13|35 13 32 | 1,327
| | summit. | | |
| | | | |
* 370 |G. Gerf | beacon. |22 42 6|35 12 16 | 1,419
| | | | |
412 |G. el Naga | S. peak. |22 42 0|34 28 25 | 827
| | | | |
436 |Peak near Wadi Muqur| summit. |22 41 58|35 18 22 | 778
| | | | |
493 |G. Mishbih | S. peak. |22 41 44|34 42 41 | 988
| | | | |
432 |Peak near Wadi Muqur| summit. |22 41 40|35 17 35 | 962
| | | | |
383 |G. Muqur | „ |22 41 31|35 16 50 | 1,058
| | | | |
433 |Hill near Bir | „ |22 41 16|35 0 57 | 797
|Sararat Seyet | | | |
| | | | |
426 |Peak near Wadi | summit. |22 41 6|35 14 30 | 1,258
|Diqdib | | | |
| | | | |
438 |Peak near Wadi | „ |22 41 3|35 17 54 | 911
|Qadiloi | | | |
| | | | |
429 |Peak near Wadi | „ |22 40 51|35 9 55 | 1,227
|Eirahimib | | | |
| | | | |
371 |G. Shweib | „ |22 40 43|34 43 57 | 914
| | | | |
428 |Peak near Wadi | „ |22 40 38|35 10 29 | 1,327
|Eirahimib | | | |
| | | | |
531 |Mt. near Bir Baaneit| „ |22 40 1|35 18 15 | 909
| | | | |
404 |G. Gerf | minor |22 39 59|35 10 7 | 1,318
| | summit. | | |
| | | | |
405 |G. Korabkansi | „ |22 39 39|35 0 44 | 1,052
| | | | |
446 |G. Korabkansi | N. peak. |22 39 35|34 59 32 | 1,176
| | | | |
614 |G. Hamra Dom | „ |22 39 34|35 38 19 | 326
| | | | |
439 |Peak near Wadi | summit. |22 39 17|35 16 11 | 1,028
|Diqdib | | | |
| | | | |
* 372 |G. Korabkansi | beacon. |22 39 16|34 59 55 | 1,230
| | | | |
420 |Peak near Wadi | cairn. |22 39 11|35 10 21 | 1,298
|Difoteb | | | |
| | | | |
* 417 |G. Hamra Dom | beacon. |22 39 6|35 38 42 | 388
| | | | |
450 |Tibansi Tikam Ankwei| summit. |22 39 5|35 32 11 | 345
| | | | |
475 |Peak near Wadi | „ |22 38 20|35 11 42 | 1,344
|Sherefa | | | |
| | | | |
411 |G. Hamra Dom | central |22 38 2|35 39 12 | 381
| | peak | | |
| | | | |
473 |Hill near Wadi Um | summit. |22 37 54|35 17 56 | 926
|Saha | | | |
| | | | |
532 |Hill near Wadi Um | „ |22 37 53|35 17 56 | 932
|Saha | | | |
| | | | |
444 |G. Dreb | peak. |22 36 54|35 6 20 | 1,139
| | | | |
615 |G. Hamra Dom | S. peak. |22 36 48|35 39 36 | 317
| | | | |
443 |G. Dreb | peak. |22 36 41|35 7 0 | 1,148
| | | | |
442 |G. Dreb | „ |22 36 40|35 7 46 | 1,137
| | | | |
476 |G. Dreb | „ |22 36 16|35 9 15 | 1,176
| | | | |
478 |G. Dreb | „ |22 36 10|35 8 21 | 1,224
| | | | |
477 |G. Dreb | „ |22 36 1|35 8 56 | 1,191
| | | | |
504 |G. Kulyeit | summit. |22 35 50|34 16 38 | 724
| | | | |
441a|G. Dreb | peak. |22 35 18|35 8 24 | 1,293
| | | | |
533 |Kilia Arib | summit. |22 35 2|35 18 46 | 647
| | | | |
441 |G. Dreb | peak. |22 35 0|35 8 36 | 1,288
| | | | |
535 |G. Dreb | „ |22 34 15|35 9 42 | 1,095
| | | | |
534 |Tibashoi Tomakolat | summit. |22 33 4|35 19 40 | 464
| | | | |
* 449a|Kolmanab hill | beacon. |22 32 26|35 53 36 | 137
| | | | |
566 |Hill near Wadi Ibib | summit. |22 32 2|35 37 36 | 459
| | | | |
619 |Point near Kolmanab | — |22 31 55|35 52 40 | 110
| | | | |
612 |G. Medarai |minor peak.|22 31 23|35 13 5 | 1,103
| | | | |
520 |G. Medarai | summit. |22 30 58|35 12 5 | 1,299
| | | | |
610 |G. Medarai |minor peak.|22 30 56|35 14 37 | 922
| | | | |
485 |G. Anweiyib |N. summit. |22 30 22|34 53 42 | 871
| | | | |
* 567a|G. Eqrun (W. summit)| beacon. |22 30 10|35 37 9 | 473
| | | | |
567 |G. Eqrun |SE. summit.|22 30 0|35 37 18 | 468
| | | | |
665 |Adar Aweib Um | summit. |22 29 28|35 33 2 | 455
|Bishtit | | | |
| | | | |
577 |Granite hill | „ |22 29 19|35 54 6 | 143
| | | | |
522 |G. Medarai | S. peak. |22 29 8|35 12 4 | 1,114
| | | | |
528 |G. Anweiyib | summit. |22 29 5|34 53 32 | 864
| | | | |
587 |G. Um Rasein | N. peak. |22 28 52|35 20 44 | 791
| | | | |
* 416 |G. Um Rasein | beacon. |22 28 12|35 20 19 | 909
| | | | |
* 575 |Einiwai hill | „ |22 27 50|35 57 59 | 138
| | | | |
521 |G. Abu Hireiq |N. summit. |22 27 39|35 14 58 | 1,116
| | | | |
609 |Hill near Wadi | summit. |22 27 21|35 15 51 | 856
|Merdiyeb | | | |
| | | | |
613 |Tahaqayet | „ |22 26 47|35 40 23 | 432
| | | | |
596 |Hill near Wadi Odruk| „ |22 26 47|35 18 42 | 639
| | | | |
595 |Hill near Wadi Odruk| „ |22 26 25|35 19 17 | 615
| | | | |
582 |Granite hill | „ |22 26 23|35 56 20 | 155
| | | | |
592 |Near Wadi Odruk | peak. |22 26 9|35 20 9 | 627
| | | | |
523 |G. Abu Hireiq | highest |22 25 57|35 14 39 | 1,319
| | point. | | |
| | | | |
581 |Osnei hill | summit. |22 25 38|35 50 42 | 251
| | | | |
455 |Hill near Bir Um | „ |22 25 14|35 33 19 | 634
|Bishtit | | | |
| | | | |
472 |Mt. near Wadi Abu | „ |22 24 43|35 16 13 | 1,256
|Hireiq | | | |
| | | | |
611 |G. Adatalob Hadal | beacon. |22 24 38|35 48 22 | 381
| | | | |
451 |Titailibab | summit. |22 24 32|35 38 52 | 593
| | | | |
459 |G. Orgem | NW. peak |22 24 31|35 31 1 | 779
| | | | |
576 |G. Orgem | SE. peak. |22 24 21|35 31 11 | 775
| | | | |
488 |G. Anweiyib |NW. summit.|22 24 16|34 49 46 | 884
| | | | |
471 |Mt. near Wadi Abu | summit. |22 23 56|35 16 41 | 1,226
|Hireiq | | | |
| | | | |
486 |G. Anweiyib |SE. summit.|22 23 37|34 51 25 | 921
| | | | |
664 |Hill S. of | summit. |22 23 26|35 39 5 | 554
|Titailibab | | | |
| | | | |
422 |G. Abu Hodeid | beacon. |22 23 18|35 14 9 | 1,482
| | | | |
572 |G. Adatalob Adara | summit. |22 23 1|35 49 58 | 385
| | | | |
603 |Near Wadi Tikraneib | peak. |22 22 57|35 18 38 | 732
| | | | |
454 |G. Meis-heit-ar | summit. |22 22 37|35 34 44 | 717
| | | | |
470 |Mt. near Bir Abu | „ |22 22 31|35 17 33 | 1,074
|Hodeid | | | |
| | | | |
479 |G. Mansur Diab | „ |22 22 28|35 10 49 | 1,091
| | | | |
469 |Mt. near Bir Abu | „ |22 22 10|35 17 51 | 1,078
|Hodeid | | | |
| | | | |
457 |Hill near head of | „ |22 22 3|35 32 42 | 738
|Wadi Qidmib | | | |
| | | | |
583 |G. Tishushi Tiboki | minor |22 22 0|35 57 12 | 284
| | summit. | | |
| | | | |
647 |Abu Hodeid Oqla | summit. |22 21 29|35 17 51 | 992
| | | | |
492 |G. Um el Tiur el | „ |22 21 26|34 34 46 | 783
|Tahtani | | | |
| | | | |
666 |G. Meis-heit-ar | „ |22 21 15|35 34 48 | 721
| | | | |
580 |G. Tishushi Tiboki | highest |22 21 14|35 55 46 | 359
| | point. | | |
| | | | |
* 569a|Ti Keferiai | beacon. |22 21 0|35 49 47 | 494
| | | | |
598 |G. Hamra Tit | SW. peak. |22 20 6|35 20 44 | 642
| | | | |
461 |G. Qidmib | summit. |22 19 55|35 30 45 | 1,037
| | | | |
* 456 |O Shakafa | „ |22 19 44|35 34 42 | 751
| | | | |
597 |G. Geror |NE. summit.|22 19 31| 35 52 4 | 434
| | | | |
462 |G. Qidmib | summit. |22 19 13|35 30 23 | 1,108
| | | | |
464 |G. Qidmib | „ |22 19 4|35 29 18 | 1,070
| | | | |
463 |G. Qidmib | „ |22 18 49|35 30 15 | 1,099
| | | | |
616 |G. Geror |high point.|22 18 37|35 50 18 | 510
| | | | |
584 |G. Qidmib | summit. |22 18 18|35 29 20 | 1,089
| | | | |
453 |Adar Aqdeib | summit. |22 18 6|35 37 51 | 736
| | | | |
490 |G. Um el Tiur el | „ |22 17 56|34 41 14 | 946
|Foqani | | | |
| | | | |
602 |G. Geror | summit. |22 17 51|35 50 55 | 516
| | | | |
649 |G. el Sela | peak. |22 17 37|36 14 17 | 433
| | | | |
487 |G. Hadal Derqa | summit. |22 16 40|35 9 55 | 1,108
| | | | |
* 460 |Hadal Aweib Meisah | beacon. |22 16 39|35 31 55 | 1,224
| | | | |
650 |G. el Sela | peak. |22 16 32|36 12 59 | 560
| | | | |
491 |G. el Adraq | summit. |22 16 22|34 35 3 | 770
| | | | |
421 |Qara Saba | „ |22 16 7|35 41 34 | 778
| | | | |
601 |G. Um Seleim | „ |22 15 58|35 21 35 | 1,098
| | | | |
480 |G. Hadal Derqa | SE. peak. |22 15 50|35 10 59 | 1,090
| | | | |
585 |Hadal Aweib Meisah | minor |22 15 48|35 30 10 | 1,092
| | summit. | | |
| | | | |
604 |G. Leqaq | summit. |22 15 40|35 20 8 | 1,192
| | | | |
512 |G. Heianai |NW. summit.|22 14 40|35 1 30 | 1,007
| | | | |
668 |G. Hamida | minor |22 14 34|35 46 13 | 583
| | summit. | | |
| | | | |
620 |Qash Amir | beacon. |22 14 31|36 12 20 | 724
| | | | |
651 |G. Sul Hamid | highest |22 14 16|36 4 53 | 572
| | peak. | | |
| | | | |
568 |G. Balatitda | summit. |22 13 56|35 58 5 | 592
| | | | |
513 |G. Hilwit Hasium | NE. peak. |22 13 50|35 14 38 | 1,037
| | | | |
468 |G. Adar Qaqa | summit. |22 13 47|35 19 0 | 1,606
| | | | |
482 |G. Heianai |SE. summit.|22 13 41|35 3 11 | 1,256
| | | | |
618 |G. Hamida | minor |22 13 36|35 46 47 | 701
| | summit. | | |
| | | | |
608 |G. Adar Qaqa | „ |22 13 33|35 19 21 | 1,542
| | | | |
448 |G. Hamida | summit. |22 13 32|35 46 33 | 754
| | | | |
* 458 |Halaib Fort | centre of |22 13 25|36 38 56 | 8
| | top. | | |
| | | | |
556 |G. Elba | peak |22 13 21|36 22 23 | 820
| | near Bir | | |
| |Kansisrob. | | |
| | | | |
652 |Hill E. of G. | peak. |22 13 20|35 59 43 | 491
|Balatitda | | | |
| | | | |
555 |Karam Elba | summit. |22 13 13|36 25 40 | 586
| | | | |
525 |G. Shanaiyet | „ |22 13 4|34 49 43 | 907
| | | | |
653 |Hill near Wadi | „ |22 13 4|35 50 12 | 511
|Warabeit | | | |
| | | | |
676 |G. Elba | peak near |22 13 2|36 20 54 | 935
| | Wadi | | |
| | Yahameib. | | |
| | | | |
662 |G. Balatitda | minor |22 12 56|35 57 44 | 493
| | summit. | | |
| | | | |
489 |G. el Hateib | summit. |22 12 44|34 43 18 | 854
| | | | |
674 |Hill near Wadi | summit. |22 12 42|36 13 10 | 507
|Siamtit | | | |
| | | | |
516 |G. Hilwit Hasium | SW. peak. |22 12 30|35 13 14 | 952
| | | | |
669 |Mt. south of Hadal | summit. |22 12 21|35 30 40 | 1,072
|Aweib Meisah | | | |
| | | | |
481 |G. el Arib | „ |22 12 15|35 8 32 | 1,112
| | | | |
579a|G. Um Ein | beacon. |22 11 52|35 39 4 | 901
| | | | |
667 |Hill near head of | summit. |22 11 40|35 47 6 | 651
|Wadi Warabeit | | | |
| | | | |
467 |G. Soaorib | „ |22 11 33|35 20 13 | 1,469
| | | | |
* 536 |G. Elba | beacon. |22 11 27|36 20 52 | 1,428
| | | | |
621 |G. Elba |minor peak.|22 11 16|36 23 44 | 1,102
| | | | |
675 |G. Elba | „ |22 11 10|36 20 35 | 1,394
| | | | |
483 |G. Heleikonti | summit. |22 11 7|34 57 59 | 1,151
| | | | |
573 |G. Warabeit | „ |22 11 1|35 47 52 | 794
| | | | |
518 |G. Soaorib | „ |22 10 54|35 17 48 | 1,397
| | | | |
* 571 |Adar Aweib | beacon. |22 10 50|35 54 0 | 620
| | | | |
538 |G. Elba |minor peak.|22 10 17|36 19 34 | 1,217
| | | | |
606 |G. Soaorib | summit. |22 10 14|35 21 25 | 1,349
| | | | |
98 |G. Muqsim | cairn. |22 10 11|34 1 12 | 825
| | | | |
589 |Mt. near Wadi | summit. |22 10 10|35 30 45 | 1,266
|Baueiwai | | | |
| | | | |
537 |G. Elba | highest |22 10 3|36 21 52 | 1,435
| | point. | | |
| | | | |
617 |G. Mashushenai | summit. |22 9 54|35 49 45 | 634
| | | | |
605 |G. Soaorib | peak. |22 9 50|35 21 45 | 1,383
| | | | |
678 |G. O Sir Eirab | summit. |22 9 24|36 20 56 | 842
| | | | |
677 |Hill near W. O Sir | „ |22 9 7|36 15 56 | 724
|Hadal | | | |
| | | | |
519 |Peak near Wadi Kirir| „ |22 8 24|35 18 27 | 1,328
| | | | |
465 |G. Soaorib | „ |22 8 22|35 23 36 | 1,431
| | | | |
590 |Mt. N. of Wadi Adar | NE. peak. |22 8 16|35 31 2 | 1,294
|Ameit el Sharqi | | | |
| | | | |
670 |Hill near Wadi Aqwem| summit. |22 8 12|35 43 30 | 724
| | | | |
578 |Hill near Da-aiyob | „ |22 7 45|35 44 8 | 833
|Wushaq | | | |
| | | | |
681 |G. Hanquf |minor peak.|22 7 45|36 16 54 | 789
| | | | |
591 |Mt. N. of Wadi Adar | SW. peak. |22 7 12|35 29 54 | 1,299
|Ameit el Sharqi | | | |
| | | | |
682 |G. Hanquf |minor peak.|22 6 54 |36 17 18 | 877
| | | | |
524 |G. Um Reddam | summit. |22 6 23|34 59 55 | 1,109
| | | | |
657 |G. Miatit | W. peak. |22 6 14|35 34 12 | 1,229
| | | | |
511 |Mt. near G. Egat | summit |22 5 53|34 53 1 | 985
| | | | |
484 |G. Egat | „ |22 5 39|34 52 15 | 1,145
| | | | |
586 |G. Miatit | SE. peak. |22 5 36|35 35 34 | 1,257
| | | | |
659 |Mt. near Wadi Adar | peak. |22 5 20|35 25 30 | 1,440
|Ameit el Gharbi | | | |
| | | | |
540 |G. Hanquf | N. peak. |22 4 52|36 18 45 | 1,397
| | | | |
452 |Hill near W. Di-ib | summit. |22 4 14|36 1 32 | 491
| | | | |
655 |G. Suruk | E. peak. |22 4 10|35 38 7 | 1,059
| | | | |
588 |G. Suruk | highest |22 3 50|35 35 28 | 1,327
| | point. | | |
| | | | |
673 |Hill near G. Suruk | peak. |22 3 46|35 40 16 | 846
| | | | |
656 |G. Shendib | „ |22 3 40|35 36 1 | 1,275
| | | | |
515 |Mt. near G. Himeitra| „ |22 3 17|35 17 52 | 1,134
| | | | |
685 |G. Shendib | „ |22 3 8|36 13 44 | 1,427
| | | | |
539 |G. Shendodai | highest |22 3 1|36 25 31 | 1,529
| | peak. | | |
| | | | |
672 |Hill near G. Suruk | peak. |22 3 0|35 40 25 | 847
| | | | |
661 |G. Shiab | „ |22 2 57|35 45 18 | 855
| | | | |
* 607 |G. Hadarba | beacon. |22 2 53|36 47 23 | 217
| | | | |
654 |G. Shiab | highest |22 2 51|35 44 7 | 987
| | point. | | |
| | | | |
517 |G. Himeitra | summit. |22 2 46|35 14 19 | 1,231
| | | | |
474 |G. Is | cairn on |22 2 36|35 28 4 | 1,736
| | summit. | | |
| | | | |
599 |G. Is | peak. |22 2 24|35 27 35 | 1,659
| | | | |
627 |G. Shendodai | S. peak. |22 2 12|36 25 22 | 1,395
| | | | |
684 |Hill near G. Shendib| summit. |22 2 12|36 9 6 | 601
| | | | |
600 |G. Is | peak. |22 2 11|35 26 56 | 1,594
| | | | |
671 |Hill near G. Suruk | „ |22 1 54|35 40 20 | 903
| | | | |
593 |Mt. east of G. Is | N. peak. |22 1 38|35 31 56 | 1,290
| | | | |
570 |G. Hanquf | highest |22 1 32|36 20 14 | 1,465
| | point. | | |
| | | | |
640 |G. Shendib | peak. |22 1 26|36 14 47 | 1,724
| | | | |
641 |G. Shendib | „ |22 1 8|36 14 59 | 1,698
| | | | |
594 |Mt. east of G. Is | S. peak. |22 1 2|35 31 11 | 1,474
| | | | |
642 |G. Shendib | peak. |22 0 51|36 15 0 | 1,696
| | | | |
543 |G. Shendib | beacon. |22 0 48|36 16 30 | 1,912
| | | | |
546 |G. Shendib | peak. |22 0 46|36 14 49 | 1,674
| | | | |
544 |G. Shendib | peak. |22 0 45|36 16 10 | 1,852
| | | | |
687 |Hill near G. Shellal| summit. |22 0 40|36 9 2 | 614
| | | | |
557 |G. Shellal | peak. |22 0 39|36 30 30 | 1,269
| | | | |
529 |G. Shellal | E. peak. |22 0 34|36 30 45 | 1,279
| | | | |
574 |G. Shellal | highest |22 0 15|36 29 40 | 1,409
| | point. | | |
| | | | |
545 |G. Shendib | peak. |21 59 56|36 17 6 | 1,863
| | | | |
547 |G. Shendib | „ |21 59 49|36 15 42 | 1,668
| | | | |
550 |G. Shendib | „ |21 59 8|36 14 16 | 1,565
| | | | |
645 |G. Shendib | „ |21 59 7|36 13 22 | 1,227
| | | | |
549 |G. Shendib | „ |21 59 6|36 14 40 | 1,525
| | | | |
644 |G. Shendib | „ |21 59 0|36 15 20 | 1,552
| | | | |
646 |G. Shendib | „ |21 58 58|36 13 11 | 1,196
| | | | |
660 |Low hill near W. | summit. |21 58 24|36 4 25 | 500
|Shendib | | | |
| | | | |
541 |G. Qeda | E. peak. |21 56 24|36 28 11 | 1,850
| | | | |
542 |G. Qeda | W. peak. |21 56 16|36 26 12 | 1,872
| | | | |
514 |Hadal Aweib | summit. |21 52 40|35 22 26 | 1,780
| | | | |
628 |G. Asotriba | highest |21 51 55|36 30 26 | 2,216
| | point. | | |
| | | | |
551 |Eir Aweit | peak. |21 50 30|36 22 48 | 1,715
| | | | |
552 |Eir Aweit | „ |21 49 56|36 23 1 | 1,678
| | | | |
564 |G. Obkeik | N. peak. |21 49 55|35 39 40 | 1,837
| | | | |
548 |G. Asotriba | S. peak. |21 49 30|36 30 40 | 2,082
| | | | |
565 |G. Obkeik | S. peak. |21 49 6|35 39 29 | 1,856
| | | | |
553 |Eir Aweit | highest |21 47 57|36 22 40 | 1,853
| | peak. | | |
| | | | |
554 |Eir Aweit | peak. |21 47 38|36 22 32 | 1,759
| | | | |
658 |Adar It |sharp peak.|21 47 1|36 19 14 | 1,170
| | | | |
409 | | beacon. |21 44 21|34 36 53 | —
| | | | |
558 |Arit | peak. |21 40 26|36 22 50 | 1,529
| | | | |
559 |Arit | „ |21 39 25|36 22 32 | 1,772
| | | | |
663 |Karai Awa | summit. |21 39 18|36 10 21 | 1,056
| | | | |
562 |Arit | peak. |21 38 3|36 18 57 | 1,410
| | | | |
560 |Arit | highest |21 36 51|36 23 27 | 1,810
| | peak. | | |
| | | | |
563 |Arit |high peak. |21 36 1|36 19 52 | 1,727
| | | | |
561 |Arit | W. end of |21 35 50|36 22 48 | 1,532
| | ridge. | | |
--------+--------------------+-----------+--------+---------+---------
=Comparison of Positions determined on the Red Sea with those
previously found in Official Marine Surveys.=
It is interesting to compare the positions found for certain
triangulation points with those determined by the British
Admiralty surveyors and by Lieut. Koss, who accompanied the Austrian
research-ship “Pola” in 1895-6.[74] The three best defined points
of comparison are Berenice temple, the central peak of St. John’s
Island, and Halaib Fort. In the case of Berenice and St. John’s
Island the observation of the two prior surveys were made at stations
a little distance from my triangulation points, but the published
charts enable one to scale off the necessary corrections to reduce
the positions to those of the triangulated points. At Berenice,
the British Admiralty observation point, for which the latitude is
given as 23° 56′ 16″, is 1′ 26″ north of the temple, so
that the equivalent Admiralty latitude for the temple is 23° 54′
50″. Similarly Lieut. Koss’s observation point, where the latitude
found was 23° 56′ 27″, is 1′ 47″ north of the temple, giving
the latitude of the temple as 23° 54′ 40″. My triangulation
gives the latitude of the temple as 23° 54′ 39″, thus showing a
remarkably good agreement with that found by the “Pola” observer.
At St. John’s Island, owing to the smallness of the scale of
the available charts, it is a little more difficult to scale off
accurately the Admiralty position for the peak and the reduction
to the peak of Lieut. Koss’s point. As nearly as I can scale,
the Admiralty latitude for the peak is 23° 36′ 40″, while the
point where Lieut. Koss observed his latitude of 23° 35′ 47″,
near the south-west shore of the island, is approximately 40″ south
of the peak, giving the latitude of the peak as 23° 36′ 27″. I
found the latitude of the peak to be 23° 36′ 16″, thus again
showing as good an agreement as could be expected, having regard to
the fact that it is not easy to scale the latitude of the point much
within 10″ from the existing charts.
At Halaib Fort, the Admiralty latitude is 22° 14′ 10″, while the
“Pola” expedition found it 22° 13′ 26″, and my triangulation
gave the value 22° 13′ 25″. The close agreement between my
triangulation value and that observed by Lieut. Koss seems to prove
the Admiralty latitude of this point to be some 45″ too high.
Summarizing the latitudes of the three points for comparison we
have:—
---------------------+-----------+-----------+-------------
| Berenice |St. John’s |Halaib Fort.
| Temple. | Peak. |
+-----------+-----------+-------------
Admiralty Chart |23° 54′ 50″|23° 36′ 40″|22° 14′ 10″
| | |
“Pola” Expedition |23° 54′ 40″|23° 36′ 27″|22° 13′ 26″
| | |
Ball (Triangulation)|23° 54′ 39″|23° 36′ 16″|22° 13′ 25″
---------------------+-----------+-----------+-------------
If we make corresponding comparisons of the longitudes of these
three points, Berenice Temple, St. John’s Peak, and Halaib Fort,
we obtain much more wide divergences, as is only to be expected
from the fact that the Admiralty and “Pola” determinations were
made by transport of chronometers from Suez, which is over 500 miles
distant from Halaib.
For Berenice Temple the Admiralty longitude (obtained by applying the
scaled reduction of − 40″ to the observed longitude 35° 29′
11″ at the observation point) is 35° 28′ 31″. Lieut. Koss’s
transport of chronometers from Suez _via_ Jidda leads to a longitude
of 33° 30′ 20″ for his observation point, which lies 54″ east
of the temple; thus the “Pola” longitude for the temple is 35°
29′ 26″. My triangulation gives 35° 28′ 26″, thus agreeing
very nearly with the Admiralty value and differing by exactly 1′
from the value found by Lieut. Koss.
For St. John’s Peak, the longitude scaled from the Admiralty
Chart is 36° 10′ 20″. The observations of Lieut. Koss lead to
a longitude of 36° 12′ 38″ for his observation point, which is
about 35″ west of the peak; thus the “Pola” longitude for the
peak is 36° 13′ 13″. My triangulation gives 36° 11′ 42″,
being thus between the Admiralty and “Pola” values.
For Halaib Fort, the Admiralty longitude is 36° 37′ 3″,
while Lieut. Koss’s figures lead to the value 36° 40′ 38″;
my triangulation gives 36° 38′ 56″, thus again showing a value
between the two marine determinations.
Summarizing the longitudes obtained for the three points, we have:—
---------------------+-----------+-----------+-------------
| Berenice |St. John’s |Halaib Fort.
| Temple. | Peak. |
+-----------+-----------+-------------
Admiralty Chart |35° 28′ 31″|36° 10′ 20″|36° 37′ 3″
| | |
“Pola” Expedition |35° 29′ 26″|36° 13′ 13″|36° 40′ 38″
| | |
Ball (Triangulation)|35° 28′ 26″|36° 11′ 42″|36° 38′ 56″
---------------------+-----------+-----------+-------------
There can, of course, be no doubt of the immensely greater accuracy
of the triangulation method of determining longitude as compared
with that of chronometer transport in voyages lasting for months,
no matter how many chronometers are carried nor what care is
taken in the work. The above differences of longitude are small
when one considers that no absolute control of the chronometer of
the “Pola” expedition was obtained from October 23, 1895, when
the ship left Suez, till its return to the same port on January 27,
1896. If we examine the difference of longitude between points fairly
close together, we find rather better agreement between chronometers
and triangulation. Thus, for instance, between Berenice and Halaib,
a six days’ voyage, we have:—
--------------------+-------------+--------------
|Longitude by |Longitude by
|Chronometers |Triangulation
| (Koss). | (Ball).
+-------------+--------------
Halaib Fort | 36° 40′ 38″ | 36° 38′ 56″
| |
Berenice Temple | 35° 29′ 26″ | 35° 28′ 26″
+-------------+--------------
Difference | 1° 11′ 12″ | 1° 10′ 30″
--------------------+-------------+--------------
showing an error of only 42″, or about three seconds of time in
the six days.
The triangulation-positions:—
------------------+-------------+--------------
| Latitude N. | Longitude E.
+-------------+--------------
Berenice Temple | 23° 54′ 39″ | 35° 28′ 26″
| |
St. John’s Peak | 23° 36′ 16″ | 36° 11′ 42″
| |
Halaib Fort | 22° 13′ 25″ | 36° 38′ 56″
------------------+-------------+--------------
may therefore be taken as practically correct, and the three points
may be used as well-determined positions both for further discussion
of the “Pola” results and in further surveying expeditions in
the Red Sea.[75]
=Detail Surveying along Lines of March.=
All detail visible along lines of march from camp to camp was recorded
on plane-table sheets on a scale of 1:100,000. The usual process
was as follows: The plane-table sheet was first provided with a
graticule at 10′ intervals of latitude and longitude, and all the
triangulation points previously fixed within the area covered by the
sheet were marked in their computed places. Stations were chosen along
the route at an average distance apart of two or three kilometres,
the most commanding hills being selected, and the positions of these
were found by plane-table re-section from three or more triangulation
points. The compass, being frequently disturbed by magnetic rocks,[76]
was only used to get a first approximation to the true orientation
of the table. The plane-table station having been fixed on the map,
tacheometric readings were taken to all conspicuous points easy of
access within a radius of about two kilometres, and plotted at their
measured distances along the directions given by the alidade.
In the telemetric measurements a 5-inch tacheometer was used side
by side with the plane-table, and two staff-men were employed. As
the scale of the map was small, the sights were much longer than is
usual in tacheometry, and the maximum distance of 800 metres directly
readable by the four-metre staves employed was generally exceeded. For
the long distance readings, where the distance between two cross-wires
subtended more than the length of the staff, I devised the following
process. Bringing the centre wire to the base of the staff, a reading
of the vertical circle was taken; next, by the tangent-screw, the
wire was brought to the top of the staff, and a second reading of the
vertical circle was taken, the difference giving the angle subtended
by the four-metre staff. It is clear that the distance is as many
times greater than 800 metres, as the angle subtended is less than
17′ of arc, and the distance is thus found by simple proportion.
In the case of very long sights, even this method failed, because
the circle could only be read to half-minutes, which was too coarse
a graduation to give a good result, and in these cases the method
used was one of repetition. The wire being brought to the base of the
staff as before, and a first reading of the vertical circle taken,
the wire was brought to the top of the staff by the tangent screw,
then to the bottom again by altering the levelling screws slightly,
again to the top by the tangent screw, and so on, three or four times,
and then a second reading was taken on the vertical circle. The slight
alteration of level had no sensible influence on the result, and it
is obvious that by automatically summing up, say, four intercepts in
this way, a very much more accurate value of the subtense angle was
obtained than was possible from a single measurement. In practice
I found it was best to carry in the waistcoat pocket a card giving
the distance corresponding to any number of minutes of difference of
reading after a four-fold repetition, and it was quite practicable to
measure up to three kilometres of distance within one hundred metres
of the truth; as this only represented a millimetre on the sheet, and
as, moreover, errors were not cumulative, owing to the independent
fixation of each successive station by re-section, the accuracy was
all that could be desired, and the rapidity of measurement was very
great. In this long distance type of tacheometry, finely graduated
staves were of no use; the form of staff employed was a broad-faced
one, fifteen centimetres wide, bearing fifty-centimetre divisions
painted alternately black and white right across the whole breadth
of the staff.[77]
An average of about six or eight conspicuous points having been
telemetrically fixed from a station, the detail was sketched in around
them, and other more distant points were at the same time fixed by
plane-table intersections from several stations. At the stations the
pencil sketching of relief was by form-lines which were subsequently
replaced by hachure-rendering when inking up the sheets in camp.
Occasionally, when a high hill-station was employed overlooking a
long wadi, time was saved by reading only two distances, both in the
same wadi, one very near to the station and the other two or three
kilometres away, at the same time observing the depression-angles
to these points. The slope of the wadi being found in this way, the
depression-angles to intermediate points gave the distances of such
points without the necessity of staff reading at the intermediate
points at all. Thus, suppose the near point was close under the
station, with a distance of 500 metres and a depression-angle of 18°,
while the remote point up the wadi had a distance of three kilometres
and a depression-angle of 2° 30′. By means of a slide rule or
three-figure logarithms, the near point was found to be 163 metres
below the station, and the distant one 130 metres. A point in the
wadi estimated roughly as half way between the two would be about 146
metres below the station; so that if the observed depression-angle to
it was, say, 4° 40′, its distance would be 146/(_tan_ 4° 40′),
or 1·8 kilometres. Any possible error of preliminary estimation of
the distance in order to find the level would be without sensible
influence on the resulting true distance.
The process of traversing between stations was seldom resorted to,
as the method of fixing stations by re-section from triangulation
points is much more accurate (the errors not being cumulative)
besides being more rapid. But in certain tortuous cañon-like wadis,
where great and time-consuming climbs would have had to be undertaken
in order to see any triangulation points, the method of traversing
with the tacheometer had to be employed.
Levels along the line of march were measured trigonometrically
whenever possible; the vertical angles to one or more triangulation
points being read with the tacheometer, and the distances scaled off
the map, the differences of height, corrected for refraction, were
found by the slide rule in the same manner as in the triangulation
already described. Heights of passes and camps whence no triangulation
points were visible were determined by barometer-comparisons between
them and points of precisely determined altitude.
Names of places were written down by the guides in Arabic characters
on the spot where they were ascertained, and transliterated on the
Egyptian Government system for insertion in the map. Most of the
place-names were checked by getting the guides to give them from
several different stations.
=Detail Surveying at Occupied Triangulation Stations.=
It was generally necessary to remain for at least a week on the
mountain summits which formed the main triangulation stations,
for only on about one day in seven was the air clear enough for
sighting the beacons on the longer lines. Occasionally the entire
landscape was blotted out for ten or more consecutive days by clouds
surrounding the summit, while at other times it was possible to see
only for a limited distance round the station owing to haze. Such
times were made use of to map all visible detail within a moderate
range (say within a radius of twelve kilometres) round the station.
In this work the first stage was to find a small base, one end
of which was the station itself. Usually a minor peak of the same
range, 500 to 1,000 metres away from the station, was fairly easily
accessible, and was chosen for the other end of the base. The six-inch
theodolite being at the main station, the five-inch tacheometer was
set up at the auxiliary station, and all noteworthy hill tops, as well
as a few points along each main line of drainage, were triangulated
off this small base. The length of the base was found by including
one or two main triangulation points in the round of angles. These
minor triangles were conveniently reduced by the slide rule, and the
points plotted at once on the plane-table by means of the alidade
and the calculated distances. The base being short, it was necessary
to observe to fine marks; cracks in the rocks, and the droppings
of birds on the peaks, and the centres of selected tree trunks in
the wadis, were usually chosen. The levels of these minor points
were determined by vertical angulation in the ordinary way. Usually
about thirty points were thus fixed round each high station. Once a
number of points were fixed in the wadis, the levels of these gave
the slope, and the difference of height between any other parts of
the wadis and the station could be estimated to within a few metres by
means of the knowledge thus obtained. A sketch being now made of the
wadis, which appeared spread out almost like a map below the station,
a hundred or more points along them were selected, and their depths
below the station being very approximately known from the wadi slope,
their distances were found by observing depression angles to them
and reducing the vertical triangle by means of the slide rule on
the spot. In all, therefore, measurements were usually made of the
distances of from 100 to 200 conspicuous points in the area round
the station, and when these were plotted with the alidade on the
plane-table sheet it was not difficult to sketch in all the detail
with considerable accuracy. Usually it was not possible to see all
round the mountain from the station itself, so that subsidiary
plane-table stations near the main one were necessary. In other
cases more than one small base was measured in order to get good
angles to various points by the minor triangulation.
By the combined use of minor triangulation for peaks, and vertical
angulation for points situated along drainage lines, it was found
that far more sketching could be done in a few days at a main station
than would have been possible in the same time by tacheometric work
on the lower ground, and that of greater accuracy. More than half
of the entire detail sketching was in fact done at the main stations.
=Survey of the Coast-line.=
In the earlier portion of the work, _i.e._, north of latitude 24°,
the work on the coast-line was confined to the fixation of prominent
points such as spurs and tips of islands. Some of these were fixed
as intersected points during the triangulation, while others were
determined by observing the depression angle and azimuth to them from
trigonometrical stations of known altitude. In this latter method,
taking the mean coefficient of refraction as 0·13, the formula[78]
employed was
_d_ = 35·497 (θ − √{θ² − 11621 _h_})
where _d_ = distance in metres, θ = depression angle in seconds,
and _h_ = altitude of station in metres. This formula is rather
tedious to work out, though the work is relatively not so great if
a number of points are to be calculated from observations at the
same station. Prominent points having been fixed in this way, the
coast-line north of 24° was sketched in from the Admiralty Chart,
adjusting the longitude to fit the points fixed.
It was sometimes a little difficult, however, to identify the fixed
points on the existing charts, and hence I tried to find some
process of surveying the entire remaining coast-line _de novo_
in detail. Traversing along the coast was placed out of question
by the great expenditure of time and money which it would have
entailed. Eventually I was led to devise a new method, by which long
stretches of coast-line could be mapped by polar co-ordinates from
mountain stations with great speed and accuracy. The directions of
a series of points sufficiently close together along the coast were
taken by theodolite, and the depression angles simultaneously observed
with the vertical circle. Then, instead of computing the distances to
the points, they were plotted by a special scale graduated directly
in angles of dip; by thus doing away with all calculation at the
station, it was possible to lay down the points on the chart as
fast as the observations could be taken, usually at the rate of
four or five points a minute, and it was frequently possible to
map thirty kilometres or more of coast-line in an hour with great
accuracy. As I have given a full account of this new method in
a separate publication,[79] I shall not go into it further here,
but would refer those interested to the publication just mentioned.
With the aid of the new method the entire coast-line from just north
of Ras Benas southwards to the parallel of 22°, a distance of over
200 miles, was mapped in detail on the 100,000 scale. I had frequent
opportunities of testing the accuracy of the delineation of the coast,
both by mapping the same stretch from two widely-distant stations of
different heights, and by subsequently surveying small portions of
the coast directly by plane-table and tacheometer from triangulation
points on or near the coast; and in all cases I found the accuracy
to be very high, the differences found rarely exceeding the thickness
of a line on the map. The tides in the Red Sea are so small in range
(generally only about a metre) that variations of sea-level were
practically negligible during the operations. Bearing in mind the
great difficulties attending the survey of so inhospitable a coast
by the ordinary method of traversing, I believe the resulting outline
of the coast on my maps is very much more correct than that shown on
any previous charts. An accurate delineation of the coast-line in
this region is of course chiefly of value as indicating the extent
of land; it is of little importance to the navigator, for whom the
positions of the outlying dangerous reefs, mapped by the Admiralty
surveyors, are far more important.
=Location of the Administrative Boundary between Egypt and the Sudan.=
By an Arrêté of the Ministry of Interior issued in 1902 it was
enacted that the boundary between the administrative divisions of
Egypt and the Sudan should be as follows:—
Commencing at Bir Shalatein on the coast of the Red Sea, the limit
runs to Bir Meneiga, thence to Gebel Niqrub, thence to Gebel Um el
Tiur and to Deiga. From Deiga the line continues to Bir Esmet Omar,
thence to Gebel Bartazuga, and finally to the Nile at Korosko.
This frontier was defined after a commission had sat, at the Mudiria
of Aswân, to make enquiries as to the vested rights of the Bedouin
tribes, the guiding principle being that all Bisharin tribes should
be under Sudan administration, and all Ababda tribes (with one
exception) under the Government of Egypt. A map accompanied the
decision, but was of a very rough character, and the positions of
the points specified were not known within several miles.
Part of my work comprised the precise fixation of the points specified
in the Arrêté, with a view to laying down the boundary accurately
on a map. As was natural in the case of a boundary settled without
careful reference to the ground, certain difficulties arose in the
location. In the first place, there are two distinct Gebels Niqrub,
and two distinct Gebels Um el Tiur. I assumed the higher mountain of
each pair to be the one indicated. Secondly, the precise point of the
mountain was unspecified; I assumed the highest peak to be the point
referred to. Thirdly, the text of the Arrêté disagrees with the
map accompanying it, in that the map shows the line curved to pass
close to Gebel Mishbih, which is not mentioned in the Arrêté. I
assumed the text of the order to be determinative, and that between
the points specified the limit followed great circles on the globe,
_i.e._, practically straight lines on the map. The locality called
Deiga was not visited, and can only be approximately fixed; it
is said by guides to be a narrow road near Gebel Muqsim, of which
mountain several peaks were fixed by triangulation.
The following table gives the positions found for the various points
along the boundary from the sea to the meridian of 34° (1) from my
survey operations, and (2) as scaled from the map accompanying the
Ministerial Arrêté. A comparison of the two sets of positions will
show how much the survey has added to our knowledge of the geography
of this part of the desert.
-------------------+-----------------------+------------------------
| Latitude N. | Longitude E.
Point. +-----------------------+------------------------
| From my | From | From my | From
| Survey. |Arrêté Map.| Survey. |Arrêté Map.
-------------------+-----------+-----------+-----------+------------
Bir Shalatein |23° 8′ 5″|22° 39′ 0″|35° 36′ 28″|36° 2′ 30″
| | | |
Bir Meneiga |22° 47′ 8″|22° 41′ 30″|35° 12′ 20″|35° 2′ 30″
| | | |
Gebel Niqrub (El |22° 51′ 29″|22° 48′ 0″|34° 56′ 48″|34° 51′ 0″
Foqani) | | | |
| | | |
Gebel Um el Tiur |22° 17′ 54″|22° 18′ 30″|34° 41′ 1″|34° 32′ 0″
(El Foqani) | | | |
| | | |
Deiga (approx.) |22° 10′ 0″|22° 9′ 0″|34° 1′ 0″|34° 3′ 0″
-------------------+-----------+-----------+-----------+------------
=Variation of the Compass.=
Careful observations were made of the variation of the compass at
three stations, _viz._, Berenice Temple, Abu Saafa Springs, and near
Halaib Fort,[80] these three points being selected as being well-known
places and at the same time likely to be free from local magnetic
disturbance. Berenice is on the coast-plain where only coral and
sand occur; Abu Saafa is in a sandstone district about 100 kilometres
south-west of Berenice, and Halaib is on the calcareous and gypseous
rocks of the coast about 220 kilometres south-east of Abu Saafa.
The instrument used was a five-inch theodolite fitted with a good
trough compass. A lens was used to bring the needle accurately to
zero, and the sun or a star was employed to find the true meridian. In
each case several observations, each with an independent setting
of the needle, were made, and the mean taken. The values obtained
were:—
-------------------+---------------------------+------------------
Place. | Date and Time. |Compass-Variation
| | West.
-------------------+---------------------------+------------------
Berenice Temple |January 6, 1907, 5·30 p.m. | 2° 44′
| |
Abu Saafa Springs |October 25, 1907, 4 p.m. | 2° 37′
| |
Near Halaib Fort |May 7, 1908, 10 a.m. | 2° 18′
-------------------+---------------------------+------------------
In order to find to what degree of accuracy the results of these
determinations might be relied on, the instrument used was tested
against the Kew magnetometer at the Khedivial Observatory, Helwân,
after the completion of the work. Three observations for the
declination at Helwân gave the westerly variation as
2° 41′·2
2° 58′·8
2° 55′·0
--------
Mean 2° 55′·0
--------
while the true declination as given by the Kew magnetometer at the
same time was 2° 52′ 5″. Thus it appears reasonable to believe
the observed values to be within about 5′ of the truth.
It is rather curious to note that the declination observed at Abu
Saafa is less than that at Berenice, which lies further east, even
if allowance is made for the secular change in the interval. The
difference from what one would expect is, however, possibly owing to
errors of observation of the magnitude above-mentioned, or it may be
due to a slight local influence of magnetic rocks underground at Abu
Saafa, where the ground is near to the base of the Nubian sandstone
beds, which rest presumably on eruptive and metamorphic rocks.
It is interesting to compare the observations of declination at
Berenice and Halaib with those recorded by ROSSLER[81] at the same
places in 1895. Thus we have:—
----------------------------------+----------------------------------
Berenice. | Mersa Halaib.
------------------------+---------+-----------------------+----------
Rossler, Nov. 27, 1895 |3° 54′ |Rossler, Nov. 18, 1895 |3° 36′
| | |
Ball, Jan. 6, 1907 |2° 44′ |Ball, May 7, 1908 |2° 18′
+---------+ +----------
Diff. in 11·1 years|1° 10′ | Diff. in 12·5 years|1° 18′
| | |
Yearly decrease| 6′·3 | Yearly decrease| 6′·3
------------------------+---------+-----------------------+----------
We thus arrive at a yearly secular diminution of declination of
6′ 3″, confirming the value arrived at by Mr. KEELING[82] for
the rate of secular change in the Red Sea area from a comparison of
other observations. It may be therefore concluded that the rate of
3′ per annum given in the “Admiralty Pilot”[83] is only about
half the true value.
Travellers in the Eastern Desert should exercise care in the reliance
they place on compass bearings. Bearings taken with a compass are
generally normal in granite and sandstone country; but wherever dark
igneous and metamorphic rocks abound, disturbances are likely to
occur. Local deviations of 5° to 10° are quite common, and in some
serpentine areas even 40° of disturbance may be observed. In some
places, one can deflect the needle through a large angle by means
of a fragment of the rock no larger than a nut, so rich are some of
the basic rocks in magnetic minerals. Some lumps of rock even show
strong polarity, attracting or repelling the north pole of the needle
according as one part or another of the lump is presented to it.
* * * * *
[Footnote 62: This measurement was made in conjunction with
Messrs. Villiers Stuart, Charteris Stewart, and Clarke.]
[Footnote 63: The logarithms A′, B, and C are taken from
Merriman’s _Precise Surveying and Geodesy_, 1899, 255. p.]
[Footnote 64: CHAUVENET (_Spherical and Practical Astronomy_, Vol. I,
p. 283) shows that when both latitude and time are required, the three
stars should differ in azimuth by 120° to give the most accurate
results. But when only the latitude is required the stars are best
selected near to the meridian north and south of the zenith. This
is evident by considering that if two stars could be observed to
culminate at the same altitude on opposite sides of the zenith,
the latitude would be precisely determined independently of any
reference to time.]
[Footnote 65: I am indebted to Mr. B. H. Wade, of the Survey
Department, for drawing my attention to this method.]
[Footnote 66: The signs of the coefficients follow from those of
the trigonometrical functions; but it is useful to remember that the
coefficient of _d_φ is + or − according as the star is north or
south, while that of _dT_ is + or − according as the star is east
or west of the meridian.]
[Footnote 67: CHAUVENET, _Astronomy_, Vol. I, p. 283.]
[Footnote 68: In this connexion it is interesting to note that as the
general level of the country to the south of Gebel Um Heshenib is some
250 metres higher than that to the north of it, the plumb-line will
be deflected to the south by local attraction, thus explaining why
the observed latitude at that station exceeds by so much the value
calculated from the triangulation. Berenice temple, on the other
hand, is on a coast-plain remote from mountains, and the observed
latitude agrees closely with the calculated one.]
[Footnote 69: The method of observation and reduction was that usually
described in text books of field astronomy. _See_, for instance,
Michie and Harlow’s _Practical Astronomy_, 1902, pp. 161-168,
and the tables on pp. 198-201 of the same work.]
[Footnote 70: The Sudan Survey’s positions are all south-east of
those which I obtained for the same points.]
[Footnote 71: For calculations of this type and for tacheometric
and other reductions in the field, the Nessler “Universal” slide
rule, which is specially designed for surveyors, was found to be a
most valuable time-saver. _See_ my paper in the _Cairo Scientific
Journal_, “On the Use of the Slide-rule in Surveying,” Dec. 1907.]
[Footnote 72: A careful discussion which I have recently undertaken
of the entire series of reciprocal observations made during the three
seasons’ work shows that _k_ varies according to the altitude of
the lines and according as the lines pass over land or sea. I hope
later to publish a separate account of this discussion, which has an
important bearing on the vertical distribution of temperature in the
air. But I may here state that for overland lines the formula _k_ =
0·1503 + 0·0000164 (_h_ − 830), where _h_ is the mean altitude
of the line in metres, gives a good agreement with the observations;
while on oversea lines at altitudes above 100 metres _k_ is always
very near to 0·135. The errors in the resulting altitudes of
intersected points due to the uniform employment of _k_ = 0·13,
are very trifling, and will seldom exceed one or two metres; for
example, at a distance of thirty kilometres the substitution of _k_
= 0·16 for _k_ = 0·13 will only change the altitude by two metres.]
[Footnote 73: This number 1210 represents the significant figures
of √{106·84}, 6·84 metres being the correction given by (1 −
_k_)/2_r_ _d_² for a distance of ten kilometres.]
[Footnote 74: _Berichte der Commission für Oceanographische
Forschungen_, Sechste Reihe, Wien, 1898, pp. 13, 14.]
[Footnote 75: In particular, the adoption of the above three
longitudes as of equal accuracy with Suez will lead to a better
longitude for Jidda. The longitude of Jidda is at present fixed only
by chronometer transport from Suez, a distance of some 650 miles; but
by regarding Halaib as a fixed point the distance of comparison can
be reduced to 150 miles. The data for this revision of the longitude
of Jidda already exist in the Reports of the “Pola” expedition,
and the discussion is certainly worth undertaking before any future
surveys are conducted in the central portion of the Red Sea.]
[Footnote 76: The disturbance of the needle was of course most
frequent in the areas where dark igneous and metamorphic rocks
prevailed; in these regions disturbances of 10° were very frequent,
and in some cases, as for example on the serpentine deposits of
Sikait, as much as 40° was noticed. In the sandstone areas no
disturbances were marked.]
[Footnote 77: I have given a somewhat fuller account of this
process in a little paper on “Long-distance Tacheometry.” _Cairo
Scientific Journal_, Vol. IV, February 1910.]
[Footnote 78: JORDAN, _Handbuch der Vermessungskunde_. Stuttgart,
1897. Bd. II, p. 522.]
[Footnote 79: _A New Method of Coast Surveying_, Survey Department
Paper, No. 21. Cairo, 1911.]
[Footnote 80: The observations at Halaib were made at a point far
enough from the fort to avoid any chance of disturbance by the iron
rails which form part of the building.]
[Footnote 81: _Berichte der Commission für Oceanographische
Forschungen_, Sechste Reihe. Wien, 1898. pp. 221, 223.]
[Footnote 82: _Magnetic Observations in Egypt_, 1895-1905, Survey
Dept. Paper, No. 6. Cairo, 1907. p. 18.]
[Footnote 83: _Red Sea and Gulf of Aden Pilot._ 5th
edition. 1900. p. 7.]