[1] Of the 30 genera or subgenera which Swainson included in his
_Natural Arrangement and Relations of the Family of Flycatchers_
(published in 1838), at least 19 do not belong to the _Muscicapidae_
at all, and one of them, _Todus_, not even to the order _Passeres_.
It is perhaps impossible to name any ornithological work whose
substance so fully belies its title as does this treatise. Swainson
wrote it filled with faith in the so-called "Quinary System"--that
fanciful theory, invented by W.S. Macleay, which misled and kept back
so many of the best English zoologists of his generation from the
truth,--and, unconsciously swayed by his bias, his judgment was
warped to fit his hypothesis.
[2] By some writers this section is distinguished as _Butalis_ of
Boie, but to do so seems contrary to rule.
FLYGARE-CARLEN, EMILIE (1807-1892), Swedish novelist, was born in
Stromstad on the 8th of August 1807. Her father, Rutger Smith, was a
retired sea-captain who had settled down as a small merchant, and she
often accompanied him on the voyages he made along the coast. She
married in 1827 a doctor named Axel Flygare, and went with him to live
in the province of Smaland. After his death in 1833 she returned to her
old home and published in 1838 her first novel, _Waldemar Klein_. In the
next year she removed to Stockholm, and married, in 1841, the jurist and
poet, Johan Gabriel Carlen (1814-1875). Her house became a meeting-place
for Stockholm men of letters, and for the next twelve years she produced
one or two novels annually. The premature death of her son Edvard
Flygare (1829-1853), who had already published three books, showing
great promise, was followed by six years of silence, after which she
resumed her writing until 1884. The most famous of her tales are _Rosen
pa Tistelon_ (1842; Eng. trans. _The Rose of Tistelon_, 1842);
_Enslingen pa Johannesskaret_ (1846; Eng. trans. _The Hermit_, 4 vols.,
1853); and _Ett Kopemanshus i skargarden_ (1859; _The Merchant's House
on the Cliffs_). Fru Carlen published in 1878 _Minnen af svenskt
forfattarlif_ 1840-1860, and in 1887-1888 three volumes of _Efterskord
fran en 80- arings forfattarbana_, containing her last tales. She died
at Stockholm on the 5th of February 1892. Her daughter, Rosa Carlen
(1836-1883), was also a popular novelist.
Emilie Flygare-Carlen's novels were collected in thirty-one volumes
(Stockholm, 1869-1875).
FLYING BUTTRESS, in architecture, the term given to a structural feature
employed to transmit the thrust of a vault across an intervening space,
such as an aisle, chapel or cloister, to a buttress built outside the
latter. This was done by throwing a semi-arch across to the vertical
buttress. Though employed by the Romans and in early Romanesque work, it
was generally masked by other constructions or hidden under a roof, but
in the 12th century it was recognized as rational construction and
emphasized by the decorative accentuation of its features, as in the
cathedrals of Chartres, Le Mans, Paris, Beauvais, Reims, &c. Sometimes,
owing to the great height of the vaults, two semi-arches were thrown one
above the other, and there are cases where the thrust was transmitted to
two or even three buttresses across intervening spaces. As a vertical
buttress, placed at a distance, possesses greater power of resistance to
thrust than if attached to the wall carrying the vault, vertical
buttresses as at Lincoln and Westminster Abbey were built outside the
chapterhouse to receive the thrust. All vertical buttresses are, as a
rule, in addition weighted with pinnacles to give them greater power of
resistance.
FLYING COLUMN, in military organization, an independent corps of troops
usually composed of all arms, to which a particular task is assigned. It
is almost always composed in the course of operations, out of the troops
immediately available. Mobility being its _raison d'etre_, a flying
column is when possible composed of picked men and horses accompanied
with the barest minimum of baggage. The term is usually, though not
necessarily, applied to forces under the strength of a brigade. The
"mobile columns" employed by the British in the South African War of
1899-1902, were usually of the strength of two battalions of infantry, a
battery of artillery, and a squadron of cavalry--almost exactly half
that of a mixed brigade. Flying columns are mostly used in savage or
guerrilla warfare.
"FLYING DUTCHMAN," a spectre-ship popularly believed to haunt the waters
around the Cape of Good Hope. The legend has several variants, but the
commonest is that which declares that the captain of the vessel,
Vanderdecken, was condemned for his blasphemy to sail round the cape for
ever, unable to "make" a port. In the Dutch version the skipper is the
ghost of the Dutch seaman Van Straaten. The appearance of the "Flying
Dutchman" is considered by sailors as ominous of disaster. The German
legend makes one Herr Von Falkenberg the hero, and alleges that he is
condemned to sail for ever around the North Sea, on a ship without helm
or steersman, playing at dice for his soul with the devil. Sir Walter
Scott says the "Flying Dutchman" was originally a vessel laden with
bullion. A murder was committed on board, and thereafter the plague
broke out among the crew, which closed all ports to the ill-fated craft.
The legend has been used by Wagner in his opera _Der fliegende
Hollander_.
FLYING-FISH, the name given to two different kinds of fish. The one
(_Dactylopterus_) belongs to the gurnard family (_Triglidae_), and is
more properly called flying gurnard; the other (_Exocoetus_) has been
called flying herring, though more nearly allied to the gar-pike than to
the herring. Some other fishes with long pectoral fins (_Pterois_) have
been stated to be able to fly, but this has been proved to be incorrect.
[Illustration: FIG. 1.--_Dactylopterus volitans._]
The flying gurnards are much less numerous than the _Exocoeti_ with
regard to individuals as well as species, there being only three or four
species known of the former, whilst more than fifty have been described
of the latter, which, besides, are found in numerous shoals of
thousands. The _Dactylopteri_ may be readily distinguished by a large
bony head armed with spines, hard keeled scales, two dorsal fins, &c.
The _Exocoeti_ have thin, deciduous scales, only one dorsal fin, and the
ventrals placed far backwards, below the middle of the body; some have
long barbels at the chin. In both kinds the pectoral fins are greatly
prolonged and enlarged, modified into an organ of flight, and in many
species of _Exocoetus_ the ventral fins are similarly enlarged, and
evidently assist in the aerial evolutions of these fishes. Flying-fishes
are found in the tropical and sub-tropical seas only, and it is a
singular fact that the geographical distribution of the two kinds is
nearly identical. Flying-fish are more frequently observed in rough
weather and in a disturbed sea than during calms; they dart out of the
water when pursued by their enemies or frightened by an approaching
vessel, but frequently also without any apparent cause, as is also
observed in many other fishes; and they rise without regard to the
direction of the wind or waves. The fins are kept quietly distended,
without any motion, except an occasional vibration caused by the air
whenever the surface of the wing is parallel with the current of the
wind. Their flight is rapid, greatly exceeding that of a ship going 10
m. an hour, but gradually decreasing in velocity and not extending
beyond a distance of 500 ft. Generally it is longer when the fishes fly
against, than with or at an angle to, the wind. Any vertical or
horizontal deviation from a straight line is not caused at the will of
the fish, but by currents of the air; thus they retain a horizontally
straight course when flying with or against the wind, but are carried
towards the right or left whenever the direction of the wind is at an
angle with that of their flight. However, it sometimes happens that the
fish during its flight immerses its caudal fin in the water, and by a
stroke of its tail turns towards the right or left. In a calm the line
of their flight is always also vertically straight or rather parabolic,
like the course of a projectile, but it may become undulated in a rough
sea, when they are flying against the course of the waves; they then
frequently overtop each wave, being carried over it by the pressure of
the disturbed air. Flying-fish often fall on board of vessels, but this
never happens during a calm or from the lee side, but during a breeze
only and from the weather side. In day time they avoid a ship, flying
away from it, but during the night when they are unable to see, they
frequently fly against the weather board, where they are caught by the
current of the air, and carried upwards to a height of 20 ft. above the
surface of the water, whilst under ordinary circumstances they keep
close to it. All these observations point clearly to the fact that any
deflection from a straight course is due to external circumstances, and
not to voluntary action on the part of the fish.
[Illustration: FIG. 2.--_Exocoetus callopterus._]
A little Malacopterygian fish about 4 in. long has recently been
discovered in West Africa which has the habits of a fresh-water
flying-fish. It has been named _Pantodon buchholzi_. It has very large
pectoral fins with a remarkable muscular process attached to the inner
ray. It lives in fresh-water lakes and rivers in the Congo region, and
has been caught in its flight above the water in a butterfly-net.
FLYING-FOX, or, more correctly, FOX-BAT. The first name is applied by
Europeans in India to the fruit-eating bats of the genus _Pteropus_,
which contains more than half the family (_Pteropidae_). This genus is
confined to the tropical regions of the Eastern hemisphere and
Australia. It comprises numerous species, a considerable proportion of
which occur in the islands of the Malay Archipelago. The flying-foxes
are the largest of the bats, the kalong of Java (_Pteropus edulis_)
measuring about a foot in length, and having an expanse of wing-membrane
measuring 5 ft. across. Flying-foxes are gregarious, nocturnal bats,
suspending themselves during the day head-downwards by thousands from
the branches of trees, where with their wings gathered about them, they
bear some resemblance to huge shrivelled-up leaves or to clusters of
some peculiar fruit. In Batchian, according to Wallace, they suspend
themselves chiefly from the branches of dead trees, where they are
easily caught or knocked down by sticks, the natives carrying them home
in basketfuls. They are then cooked with abundance of spices, and "are
really very good eating, something like hare." Towards evening these
bats bestir themselves, and fly off in companies to the village
plantations, where they feed on all kinds of fruit, and so numerous and
voracious are they that no garden crop has much chance of being gathered
which is not specially protected from their attacks. The flying-fox of
India (_Pteropus medius_) is a smaller species, but is found in great
numbers wherever fruit is to be had in the Indian peninsula.
FLYING-SQUIRREL, properly the name of such members of the squirrel-group
of rodent mammals as have a parachute-like expansion of the skin of the
flanks, with attachments to the limbs, by means of which they are able
to take long flying-leaps from tree to tree. The parachute is supported
by a cartilage attached to the wrist or carpus; in addition to the
lateral membrane, there is a narrow one from the cheek along the front
of each shoulder to the wrist, and in the larger species a third
(interfemoral) connecting the hind-limbs with the base of the long tail.
Of the two widely distributed genera, _Pteromys_ includes the larger and
_Sciuropterus_ the smaller species. The two differ in certain details of
dentition, and in the greater development in the former of the
parachute, especially the interfemoral portion, which in the latter is
almost absent. In _Pteromys_ the tail is cylindrical and comparatively
thin, while in _Sciuropterus_ it is broad, flat and laterally expanded,
so as to compensate for the absence of the interfemoral membrane by
acting as a supplementary parachute.
[Illustration: Pigmy African Flying-Squirrel (_Idiurus zenkeri_).]
In general appearance flying-squirrels resemble ordinary squirrels,
although they are even more beautifully coloured. Their habits, food,
&c., are also very similar to those of the true squirrels, except that
they are more nocturnal, and are therefore less often seen. The Indian
flying-squirrel (_P. oral_) leaps with its parachute extended from the
higher branches of a tree, and descends first directly and then more and
more obliquely, until the flight, gradually becoming slower, assumes a
horizontal direction, and finally terminates in an ascent to the branch
or trunk of the tree to which it was directed. The presence of these
rodents at night is made known by their screaming cries. _Sciuropterus_
is represented by _S. velucella_ in eastern Europe and northern Asia,
and by a second species in North America, but the other species of this
genus and all those of _Pteromys_ are Indo-Malayan. A third genus,
_Eupetaurus_, typified by a very large, long-haired, dark-grey species
from the mountains to the north-west of Kashmir (_Eu. cinereus_),
differs from all other members of the squirrel-family by its
tall-crowned molar teeth. It has a total length of 37 in., of which 22
are taken up by the tail.
In Africa the name of flying-squirrel is applied to the members of a
very different family of rodents, the _Anomaluridae_, which are provided
with a parachute. Since, however, this parachute is absent in some
members of the family, the most distinctive character is the presence of
a double row of spiny scales on the under surface of the tail, which
apparently aid in climbing. The flying species are also distinguished
from ordinary flying-squirrels by the circumstance that the additional
bone serving for the support of the fore part of the flying-membrane
rises from the elbow-joint instead of from the wrist. The family is
represented by two flying genera, _Anomalurus_ and _Idiurus_; the latter
containing only one very minute species (shown in the cut) characterized
by its small ears and elongated tail. Most of the species are West
African. In habits these rodents appear to be very similar to the true
flying-squirrels. The species without a parachute constitutes the genus
_Zenkerella_, and looks very like an ordinary squirrel (see RODENTIA).
In Australia and Papua the name flying-squirrel is applied to such
marsupials as are provided with parachutes; animals which naturalists
prefer to designate flying-phalangers (see MARSUPIALIA) (R. L.*)
FLYSCH, in geology, a remarkable formation, composed mainly of
sandstones, soft marls and sandy shales found extending from S.W.
Switzerland eastward along the northern Alpine zone to the Vienna basin,
whence it may be followed round the northern flanks of the Carpathians
into the Balkan peninsula. It is represented in the Pyrenees, the
Apennines, the Caucasus and extends into Asia; similar flysch-like
deposits are related to the Himalayas as the European formations are to
the Alps. The Flysch is not of the same age in every place; thus in the
western parts of Switzerland the oldest portions probably belong to the
Eocene period, but the principal development is of Oligocene age; as it
is traced eastward we find in the east Alps that it descends into the
upper Cretaceous, and in the Vienna region and the Carpathians it
contains intercalations which clearly indicate a lower Cretaceous horizon
for the lower parts. It appears indeed that this type of formation was in
progress of deposition at one point or another in the regions enumerated
above from Jurassic to late Tertiary times. The absence of fossils from
enormous thicknesses of Flysch makes the correlation with other
formations difficult; often the only indications of organisms are the
abundant markings supposed to represent Algae (Chondrites, &c.), which
have given rise to the term "Hieroglyphic-sandstone." The most noteworthy
exceptions are perhaps the Oligocene fish-bed of Glarus, the Eocene
nummulitic beds in Calabria, and the _Aptychus_ beds of Waidhofen. Local
phases of the Flysch have received special names; it is the "Vienna" or
"Carpathian" sandstone of those regions; the "macigno" (a soft sandstone
with calcareous cement) of the Maritime Alps and Apennines; the
"scagliose" (scaly clays) and "alberese" (limestones) of the same places
are portions of this formation. The _gris de Menton_, the _gris d'Annot_
of the Basses Alps, and the _gris d'Embrun_ of Chaillot appear in
Switzerland as the _gris de Taveyannaz_. At several places the upper
layers of the Flysch are iron-stained, as in the region of Leman and at
the foot of the Dent du Midi; it is then styled the "Red-Flysch."
Lenticular intercalations of gabbro, diabase, &c., occur in the Flysch in
Calabria on the Pyrenees. Large exotic blocks of granite, gneiss and
other crystalline rocks in coarse conglomerates are found near Vienna,
near Sonthofen in Bavaria, near Lake Thun (Wild Flysch) and at other
points, which have been variously regarded as indications of glaciation
or of coastal conditions.
FOCA (pronounced _Fawtcha_), a town of Bosnia, situated at the
confluence of the Drina and Cehotina rivers, and encircled by wooded
mountains. Pop. (1895) 4217. The town is the headquarters of a thriving
industry in silver filigree-work and inlaid weapons, for which it was
famous. With its territories enclosed by the frontiers of Montenegro and
Novi Bazar, Foca, then known as _Chocha_, was the scene of almost
incessant border warfare during the middle ages. No monuments of this
period are left except the Bogomil cemeteries, and the beautiful
mosques, which are the most ancient in Bosnia. The three adjoining towns
of Foca, Gorazda and Ustikolina were trading-stations of the Ragusans in
the 14th century, if not earlier. In the 16th century, Benedetto
Ramberti, ambassador from Venice to the Porte, described the town, in
his _Libri Tre delle Cose dei Turchi_, as _Cozza_, "a large settlement,
with good houses in Turkish style, and many shops and merchants. Here
dwells the governor of Herzegovina, whose authority extends over the
whole of Servia. Through this place all goods must pass, both going and
returning, between Ragusa and Constantinople."
FOCHABERS, a burgh of barony and village of Elginshire, Scotland. Pop.
(1901) 981. It is delightfully situated on the Spey, about 9 m. E. by S.
of Elgin, the terminus of a branch of the Highland railway connecting at
Orbliston Junction with the main line from Elgin to Keith. The town was
rebuilt in its present situation at the end of the 18th century, when
its earlier site was required for alterations in the grounds of Gordon
Castle, in which the old town cross still stands. The streets all lead
at right angles to the central square, where fairs and markets are held.
The public buildings include a library and reading-room, the court-house
and the Milne school, named after Alexander Milne, who endowed it with a
legacy of L20,000. Adjoining the town, surrounded by a park containing
many magnificent old trees, stands Gordon Castle, the chief seat of the
duke of Richmond and Gordon, erected in the 18th century. The antiquary
George Chalmers (1742-1825) and the composer William Marshall
(1748-1833) were natives of the burgh.
FOCSHANI (Rumanian _Focsani_, sometimes incorrectly written _Fokshani_
or _Fokshan_), the capital of the department of Putna, Rumania; on the
river Milcov, which formed the ancient frontier of the former
principalities of Moldavia and Walachia. Pop. (1900) 23,783; of whom
6000 were Jews. The chief buildings are the prefecture, schools,
synagogues, and many churches, including those of the Armenians and
Protestants. Focshani is a commercial centre of some importance, the
chief industries being oil and soap manufacture and tannery. A large
wine trade is also carried on, and corn is shipped in lighters to
Galatz. The annual fair is held on the 29th of April. Government
explorations in the vicinity of this town show it to be rich in
minerals, such as iron, copper, coal and petroleum. The line
Focshani-Galatz is covered by a very strong line of fortifications,
known as the Sereth Line. A congress between Russian and Turkish
diplomatists was held near the town in 1772. In the neighbourhood the
Turks suffered a severe defeat from the Austrians and Russians in 1789.
FOCUS (Latin for "hearth" or "fireplace"), a point at which converging
rays meet, toward which they are directed, or from which diverging rays
are directed; in the latter case called the virtual focus (see
MICROSCOPE; TELESCOPE; LENS). In geometry the word is used to denote
certain points (see GEOMETRY; CONIC SECTION; and PERSPECTIVE).
FOG, the name given to any distribution of solid or liquid particles in
the surface layers of the atmosphere which renders surrounding objects
notably indistinct or altogether invisible according to their distance.
In its more intense forms it hinders and delays travellers of all kinds,
by sea or land, by railway, road or river, or by the mountain path. It
is sometimes so thick as to paralyse traffic altogether. According to
the _New English Dictionary_ the word "appears to be" a back formation
from the adjective "foggy," a derivative of "fog" used with its old
meaning of aftermath or coarse grass, or, in the north of Britain, of
"moss." Such a formation would be reasonable, because wreaths of fog in
the atmospheric sense are specially characteristic of meadows and
marshes where fog, in the more ancient sense, grows.
Two other words, _mist_ and _haze_, are also in common use with
reference to the deterioration of transparency of the surface layers of
the atmosphere caused by solid or liquid particles, and in ordinary
literature the three words are used almost according to the fancy of the
writer. It seems possible to draw a distinction between mist and haze
that would be fairly well supported by usage. Mist may be defined as a
cloud of water particles at the surface of land or sea, and would only
occur when the air is nearly or actually saturated, that is, when there
is little or no difference between the readings of the dry and wet
bulbs; the word haze, on the other hand, may be reserved for the
obscuration of the surface layers of the atmosphere when the air is dry.
It would not be difficult to quote instances in which even this
distinction is disregarded in practice. Indeed, the telegraphic code of
the British Meteorological Office uses the same figure for mist and
haze, and formerly the Beaufort weather notation had no separate letter
for haze (now indicated by z), though it distinguished between f, fog,
and m, mist. It is possible, however, that these practices may arise,
not from confusion of idea, but from economy of symbols, when the
meaning can be made out from a knowledge of the associated observations.
As regards the distinction between mist and fog, careful consideration
of a number of examples leads to the conclusion that the word "fog" is
used to indicate not so much the origin or meteorological nature of the
obscurity as its effect upon traffic and travellers whether on land or
sea. It is, generally speaking, "in a fog" that a traveller loses
himself, and indeed the phrase has become proverbial in that sense. A
"fog-bell" or "fog-horn" is sounded when the atmosphere is so thick that
the aid of sound is required for navigation. A vessel is "fog-logged" or
"fog-bound" when it is stopped or detained on account of thick
atmosphere. A "fog-signal" is employed on railways when the ordinary
signals are obliterated within working distances. A "fog-bow" is the
accompaniment of conditions when a mountain traveller is apt to lose his
way.
These words are used quite irrespective of the nature of the cloud which
interferes with effective vision and necessitates the special provision;
the word "mist" is seldom used in similar connexion. We may thus define
a fog as a surface cloud sufficiently thick to cause hindrance to
traffic. It will be a _thick mist_ if the cloud consists of water
particles, a _thick haze_ if it consists of smoke or dust particles
which would be persistent even in a dry atmosphere.
It is probable that sailors would be inclined to restrict the use of the
word to the surface clouds met with in comparatively calm weather, and
that the obscurity of the atmosphere when it is blowing hard and perhaps
raining hard as well should be indicated by the terms "thick weather" or
"very thick weather" and not by "fog"; but the term "fog" would be quite
correctly used on such occasions from the point of view of cautious
navigation. If cloud, drizzling rain, or heavy rain cause such obscurity
that passing ships are not visible within working distances the sounding
of a fog-horn becomes a duty.
The number of occasions upon which fog and mist may be noted as
occurring with winds of different strengths may be exemplified by the
following results of thirty years for St Mary's, Scilly Isles, where the
observations have always been made by men of nautical experience.
+----------------------------+-----+---+---+---+---+---+----+----+-------+
| Wind Force. |0 & 1| 2 | 3 | 4 | 5 | 6 | 7 |8-12| All |
| | | | | | | | | | Winds.|
+----------------------------+-----+---+---+---+---+---+----+----+-------+
|Number of occasions of fog | | | | | | | | | |
| per 1000 observations | 8 | 7 | 9 |14 | 6 | 3 | <1 | <1 | 47 |
|Number of occasions of mist | | | | | | | | | |
| per 1000 observations | 5 | 6 |11 |22 |20 |12 | 6 | 2 | 84 |
+----------------------------+-----+---+---+---+---+---+----+----+-------+
The use of the word "fog" in the connexion "high fog," to describe the
almost total darkness in the daytime occasionally noted in London and
other large cities due to the persistent opaque cloud in the upper air
without serious obscuration of the surface layers, is convenient but
incorrect.
Regarding "fog" as a word used to indicate the state of the atmosphere
as regards transparency considered with reference to its effect upon
traffic, a scale of fog intensity has been introduced for use on land or
at sea, whereby the intensity of obscurity is indicated by the numbers 1
to 5 in the table following. At sea or in the country a fog, as a rule,
is white and consists of a cloud of minute water globules, of no great
vertical thickness, which disperses the sunlight by repeated reflection
but is fully translucent. In dust-storms and sand-storms dark or
coloured fog clouds are produced such as those which are met with in the
Harmattan winds off the west coast of Africa. In large towns the fog
cloud is darkened and intensified by smoke, and in some cases may be
regarded as due entirely to the smoke.
_Description of Effects._
+------------------+-----+--------------------------+-----------------------------+------------------------+
| Name. | No. | On Land. | On Sea. | On River. |
+------------------+-----+--------------------------+-----------------------------+------------------------+
| | 1 | Objects indistinct, but | Horizon invisible, but | Objects indistinct, but|
|Slight Fog or Mist| | traffic by rail or road| lights and landmarks | navigation unimpeded |
| | | unimpeded | visible at working | |
| | | | distances | |
| | / 2 | Traffic by rail requires | / Lights, passing vessels | Navigation impeded, |
|Moderate Fog |< | additional caution |< and landmarks generally | additional caution |
| | | 3 | Traffic by rail or road | | indistinct under a mile.| required |
| | \ | impeded | \ Fog signals are sounded | |
| | / 4 | Traffic by rail or road | / Ships' lights and vessels | Navigation suspended |
|Thick Fog |< | impeded |< invisible at 1/4 mile or| |
| | | 5 | Traffic by rail or road | | less | |
| | \ | totally disorganized | \ | |
+------------------+-----+--------------------------+-----------------------------+------------------------+
The physical processes which produce fogs of water particles are
complicated and difficult to unravel. We have to account for the
formation and maintenance of a cloud at the earth's surface; and the
process of cloud-formation which is probably most usual in nature,
namely, the cooling of air by rarefaction due to the reduction of
pressure on ascent, cannot be invoked, except in the case of the fogs
forming the cloud-caps of hills, which are perhaps not fairly included.
We have to fall back upon the only other process hitherto recognized as
causing cloudy condensation in the atmosphere, that is to say, the
mixing of masses of mist air of different temperatures. The mixing is
brought about by the slow motion of air masses, and this slow motion is
probably essential to the phenomenon.
TABLE I.--_Air travelling from Northern Africa to Northern Russia,
round by the Azores._
+------------------------------------+---------+---------+---------+---------+-----------+
| Successive Temperatures of sea | 68 deg. | 68 deg. | 67 deg. | 59 deg. | 54 deg. F.|
| " " " air | 68 deg. | 70 deg. | 67 deg. | 60 deg. | 56 deg. F.|
| " States of the atmosphere | clear | clear | clear | shower | mist |
+------------------------------------+---------+---------+---------+---------+-----------+