[1] From _Diar_, land, and Bekr (i.e. Abu Bekr, the caliph).
DIARRHOEA (from Gr. [Greek: dia], through, [Greek: rheo], flow), an
excessive looseness of the bowels, a symptom of irritation which may be
due to various causes, or may be associated with some specific disease.
The treatment in such latter cases necessarily varies, since the symptom
itself may be remedial, but in ordinary cases depends on the removal of
the cause of irritation by the use of aperients, various sedatives being
also prescribed. In chronic diarrhoea careful attention to the diet is
necessary.
DIARY, the Lat. _diarium_ (from _dies_, a day), the book in which are
preserved the daily memoranda regarding events and actions which come
under the writer's personal observation, or are related to him by
others. The person who keeps this record is called a diarist. It is not
necessary that the entries in a diary should be made each day, since
every life, however full, must contain absolutely empty intervals. But
it is essential that the entry should be made during the course of the
day to which it refers. When this has evidently not been done, as in the
case of Evelyn's diary, there is nevertheless an effort made to give the
memoranda the effect of being so recorded, and in point of fact, even in
a case like that of Evelyn, it is probable that what we now read is an
enlargement of brief notes jotted down on the day cited. When this is
not approximately the case, the diary is a fraud, for its whole value
depends on its instantaneous transcript of impressions.
In its primitive form, the diary must always have existed; as soon as
writing was invented, men and women must have wished to note down, in
some almanac or journal, memoranda respecting their business, their
engagements or their adventures. But the literary value of these would
be extremely insignificant until the spirit of individualism had crept
in, and human beings began to be interesting to other human beings for
their own sake. It is not, therefore, until the close of the Renaissance
that we find diaries beginning to have literary value, although, as the
study of sociology extends, every scrap of genuine and unaffected record
of early history possesses an ethical interest. In the 17th century,
diaries began to be largely written in England, although in most cases
without any idea of even eventual publication. Sir William Dugdale
(1605-1686) had certainly no expectation that his slight diary would
ever see the light. There is no surviving record of a journal kept by
Clarendon, Richard Baxter, Lucy Hutchinson and other autobiographical
writers of the middle of the century, but we may take it for granted
that they possessed some such record, kept from day to day. Bulstrode
Whitelocke (1605-1675), whose _Memorials of the English Affairs_ covers
the ground from 1625 to 1660, was a genuine diarist. So was the elder
George Fox (1624-1690), who kept not merely "a great journal," but "the
little journal books," and whose work was published in 1694. The famous
diary of John Evelyn (1620-1706) professes to be the record of seventy
years, and, although large tracts of it are covered in a very
perfunctory manner, while in others many of the entries have the air of
having been written in long after the event, this is a very interesting
and amusing work; it was not published until 1818. In spite of all its
imperfections there is a great charm about the diary of Evelyn, and it
would hold a still higher position in the history of literature than it
does if it were not overshadowed by what is unquestionably the most
illustrious of the diaries of the world, that of Samuel Pepys
(1633-1703). This was begun on the 1st of January 1660 and was carried
on until the 29th of May 1669. The extraordinary value of Pepys' diary
consists in its fidelity to the portraiture of its author's character.
He feigns nothing, conceals nothing, sets nothing down in malice or
insincerity. He wrote in a form of shorthand intelligible to no one but
himself, and not a phrase betrays the smallest expectation that any eye
but his own would ever investigate the pages of his confession. The
importance of this wonderful document, in fact, lay unsuspected until
1819, when the Rev. John Smith of Baldock began to decipher the MS. in
Magdalene College, Cambridge. It was not until 1825 that Lord Braybrooke
published part of what was only fully edited, under the care of Mr
Wheatley, in 1893-1896. In the age which succeeded that of Pepys, a
diary of extraordinary emotional interest was kept by Swift from 1710 to
1713, and was sent to Ireland in the form of a "Journal to Stella"; it
is a surprising amalgam of ambition, affection, wit and freakishness.
John Byrom (1692-1763), the Manchester poet, kept a journal, which was
published in 1854. The diary of the celebrated dissenting divine, Philip
Doddridge (1702-1751), was printed in 1829. Of far greater interest are
the admirably composed and vigorously written journals of John Wesley
(1703-1791). But the most celebrated work of this kind produced in the
latter half of the 18th century was the diary of Fanny Burney (Madame
D'Arblay), published in 1842-1846. It will be perceived that, without
exception, these works were posthumously published, and the whole
conception of the diary has been that it should be written for the
writer alone, or, if for the public, for the public when all prejudice
shall have passed away and all passion cooled down. Thus, and thus only,
can the diary be written so as to impress upon its eventual readers a
sense of its author's perfect sincerity and courage.
Many of the diaries described above were first published in the opening
years of the 19th century, and it is unquestionable that the interest
which they awakened in the public led to their imitation. Diaries ceased
to be rare, but as a rule the specimens which have hitherto appeared
have not presented much literary interest. Exception must be made in
favour of the journals of two minor politicians, Charles Greville
(1794-1865) and Thomas Creevey (1768-1838), whose indiscretions have
added much to the gaiety of nations; the papers of the former appeared
in 1874-1887, those of the latter in 1903. The diary of Henry Crabb
Robinson (1775-1867), printed in 1869, contains excellent biographical
material. Tom Moore's journal, published in 1856 by Lord John Russell,
disappointed its readers. But it is probable, if we reason by the
analogy of the past, that the most curious and original diaries of the
19th century are still unknown to us, and lie jealously guarded under
lock and key by the descendants of those who compiled them.
It was natural that the form of the diary should appeal to a people so
sensitive to social peculiarities and so keen in the observation of them
as the French. A medieval document of immense value is the diary kept by
an anonymous _cure_ during the reigns of Charles VI. and Charles VII.
This _Journal d'un bourgeois de Paris_ was kept from 1409 to 1431, and
was continued by another hand down to 1449. The marquis de Dangeau
(1638-1720) kept a diary from 1684 till the year of his death; this
although dull, and as Saint-Simon said "of an insipidity to make you
sick," is an inexhaustible storehouse of facts about the reign of Louis
XIV. Saint-Simon's own brilliant memoirs, written from 1691 to 1723, may
be considered as a sort of diary. The lawyer, Edmond Barbier
(1689-1771), wrote a journal of the anecdotes and little facts which
came to his knowledge from 1718 to 1762. The studious care which he took
to be correct, and his manifest candour, give a singular value to
Barbier's record; his diary was not printed at all until 1847, nor, in
its entirety, until 1857. The song-writer, Charles Colle (1709-1783),
kept a _journal historique_ from 1758 to 1782; it is full of vivacity,
but very scandalous and spiteful. It saw the light in 1805, and
surprised those to whom Colle, in his lifetime, had seemed the most
placid and good-natured of men. Petit de Bachaumont (1690-1770) had
access to remarkable sources of information, and his _Memoires secrets_
(a diary the publication of which began in 1762 and was continued after
Bachaumont's death, until 1787, by other persons) contains a valuable
mass of documents. The marquis d'Argenson (1694-1757) kept a diary, of
which a comparatively full text was first published in 1859. In recent
times the posthumous publication of the diaries of the Russian artist,
Marie Bashkirtseff (1860-1884), produced a great sensation in 1887, and
revealed a most remarkable temperament. The brothers Jules and Edmond de
Goncourt kept a very minute diary of all that occurred around them in
artistic and literary Paris; after the death of Jules, in 1870, this was
continued by Edmond, who published the three first volumes in 1888. The
publication of this work was continued, and it produced no little
scandal. It is excessively ill-natured in parts, but of its vivid
picturesqueness, and of its general accuracy as a transcript of
conversation, there can be no two opinions. (E. G.)
DIASPORE, a native aluminium hydroxide, AlO(OH), crystallizing in the
orthorhombic system and isomorphous with gothite and manganite. It
occurs sometimes as flattened crystals, but usually as lamellar or scaly
masses, the flattened surface being a direction of perfect cleavage on
which the lustre is markedly pearly in character. It is colourless or
greyish-white, yellowish, sometimes violet in colour, and varies from
translucent to transparent. It may be readily distinguished from other
colourless transparent minerals, with a perfect cleavage and pearly
lustre--mica, talc, brucite, gypsum--by its greater hardness of 6-1/2-7.
The specific gravity is 3.4. When heated before the blowpipe it
decrepitates violently, breaking up into white pearly scales; it was
because of this property that the mineral was named diaspore by R. J.
Hauy in 1801, from [Greek: diaspeirein], "to scatter." The mineral
occurs as an alteration product of corundum or emery, and is found in
granular limestone and other crystalline rocks. Well-developed crystals
are found in the emery deposits of the Urals and at Chester,
Massachusetts, and in kaolin at Schemnitz in Hungary. If obtainable in
large quantity it would be of economic importance as a source of
alumina. (L. J. S)
DIASTYLE (from Gr. [Greek: dia], through, and [Greek: stylos], column),
in architecture, a term used to designate an intercolumniation of three
or four diameters.
DIATOMACEAE. For the knowledge we possess of these beautiful plants, so
minute as to be undiscernible by our unaided vision, we are indebted to
the assistance of the microscope. It was not till towards the close of
the 18th century that the first known forms of this group were
discovered by O. F. Muller. And so slow was the process of discovery in
this field of scientific research that in the course of half a century,
when Agardh published his _Systema algarum_ in 1824, only forty-nine
species included under eight genera had been described. Since that time,
however, with modern microscopes and microscopic methods, eminent
botanists in all parts of the civilized world have studied these minute
plants, with the result that the number of known genera and species has
been greatly increased. Over 10,000 species of diatoms have been
described, and about 1200 species and numerous varieties occur in the
fresh waters and on the coasts of Great Britain and Ireland. Rabenhorst,
in the index to his _Flora Europaea algarum_ (1864) enumerated about
4000 forms which had up to that time been discovered throughout the
continent of Europe.
[Illustration: FIG. 1. A and B, _Melosira arenaria._ C-E, _Melosira
varians._ E, showing formation of auxospore.]
[Illustration: FIG. 2.--_Synedra Ulna._]
The diatoms are more commonly known among systematic botanists as the
Bacillarieae, particularly on the continent of Europe, and although such
an immense number of very diverse forms are included in it, the group as
a whole exhibits a remarkable uniformity of structure. The Bacillarieae
is one of the large groups of Algae, placed by some in close proximity
to the Conjugatae and by others as an order of the Brown Algae (or
Phaeophyceae), but their characters are so distinctive and their
structure is so uniform as to warrant the separation of the diatoms as a
distinct class. The affinities of the group are doubtful.
The diatoms exhibit great variety of form. While some species are
circular and more or less disk-shaped, others are oval in outline. Some
are linear, as _Synedra Ulna_ (fig. 2), others more or less crescentic;
others again are cuneate, as _Podosphenia Lyngbyii_ (fig. 3); some few
have a sigmoid outline, as _Pleurosigma balticum_ (fig. 4); but the
prevailing forms are naviculoid, as in the large family Naviculaceae, of
which the genus _Navicula_ embraces upwards of 1000 species. They vary
also in their modes of growth,--some being free-floating, others
attached to foreign bodies by simple or branched gelatinous stalks,
which in some species are short and thick, while in others they are long
and slender. In some genera the forms are simple, while in others the
frustules are connected together in ribbon-like filaments, or form, as
in other cases, zigzag chains. In some genera the individuals are naked,
while in many others they are enclosed in a more or less definite
gelatinous investment. The conditions necessary to their growth are
moisture and light. Wherever these circumstances coexist, diatomaceous
forms will almost invariably be found. They occur mixed with other
organisms on the surface of moist rocks; in streamlets and pools, they
form a brownish stratum on the surface of the mud, or cover the stems
and leaves of water plants or floating twigs with a furry investment.
Marine forms are usually attached to various sea-weeds, and many are
found in the stomachs of molluscs, holothurians, ascidians and other
denizens of the ocean. The fresh-water forms are specifically distinct
from those incidental to salt or brackish water,--fresh-water species,
however, are sometimes carried some distance into the sea by the force
of the current, and in tidal rivers marine forms are carried up by the
force of the tide. Some notion may be formed of the extreme minuteness
of these forms from the fact that one the length of which is 1/200th of
an inch may be considered as beyond the medium size. Some few, indeed,
are much larger, but by far the greater proportion are of very much
smaller dimensions.
[Illustration: FIG. 3.--_Podosphenia Lyngbyii._]
[Illustration: FIG. 4.--_Pleurosigma balticum._]
[Illustration: FIG. 5. A-C, _Tetracyclus lacustris._ D and E,
_Tabellaria fenestrata._ F and G, _Tabellaria flocculosa._]
Diatoms are unicellular plants distinguished from kindred forms by the
fact of having their soft vegetative part covered by a siliceous case.
Each individual is known as a frustule, and the cell-wall consists of
two similar valves nearly parallel to each other, each valve being
furnished with a rim (or connecting-band) projecting from it at a right
angle.
One of these valves with its rim is slightly smaller than the other,
the smaller fitting into the larger pretty much as a pill-box fits into
its cover. This peculiarity of structure affords ample scope for the
growth of the protoplasmic cell-contents, for as the latter increase in
volume the siliceous valves are pushed out, and their corresponding
siliceous rims become broader. The connecting-bands although closely
fitting their respective valves are distinct from them, and together the
two bands form the girdle.
An individual diatom is usually described from two aspects, one in which
the surface of the valve is exposed to view--the valve view, and one in
which the girdle side is exposed--the girdle view. The valves are thin
and transparent, convex on the outside, and generally ornamented with a
variety of sculptured markings. These sculptures often present the
aspect of striae across the face of the valve, and the best lenses have
shown them to consist of a series of small cavities within the siliceous
wall of the cell. The valves of some of the marine genera exhibit a
beautiful areolated structure due to the presence of larger chambers
within the siliceous cell-wall. Many diatoms possess thickenings of the
cell-wall, visible in the valve view, in the centre of the valve and at
each extremity. These thickenings are known as the nodules, and they are
generally connected by a long median line, the raphe, which is a cleft
in the siliceous valve, extending at least some part of its length.
The protoplasmic contents of this siliceous box-like unicell are very
similar to the contents of many other algal cells. There is a living
protoplasmic layer or primordial utricle, connected either by two broad
bands or by a number of anastomosing threads with a central mass of
protoplasm in which the nucleus is embedded. The greater part of the
cavity of the cell is occupied by one or several fluid vacuoles. The
characteristic brown colour of diatoms is due to the presence of
chromatophores embedded in the lining layer of protoplasm. In number and
form these chromatophores are variable. They contain chlorophyll, but
the green colour is masked by the presence of diatomin, a brown pigment
which resembles that which occurs in the Brown Algae or Phaeophyceae.
The chromatophores contain a variable number of pyrenoids, colourless
proteid bodies of a crystalloidal character.
One of the first phenomena which comes under the notice of the observer
is the extraordinary power of motion with which the frustules are
endowed. Some species move slowly backwards and forwards in pretty much
the same line, but in the case of _Bacillaria paradoxa_ the motion is
very rapid, the frustules darting through the water in a zigzag course.
To account for this motion various theories have been suggested, none of
which appear to be altogether satisfactory. There is little doubt that
the movements are connected with the raphe, and in some diatoms there is
much evidence to prove that they are due to an exudation of mucilage.
_Classification._--The most natural system of classification of the
Bacillarieae is the one put forward by Schutt (1896), and since
generally followed by systematists. He separates them into two primary
divisions, the 'Centricae' and the 'Pennatae.' The former includes all
those diatoms which in the valve view possess a radial symmetry around a
central point, and which are destitute of a raphe (or a pseudoraphe).
The latter includes those which are zygomorphic or otherwise irregular,
and in which the valve view is generally boat-shaped or needle-shaped,
with the markings arranged in a sagittal manner on each side of a raphe
or pseudoraphe.
_Reproduction._--In the Diatomaceae, as well as in the Desmidieae, the
ordinary mode of increase is by simple cell-division. The cell-contents
within the enclosure of the siliceous case separate into two distinct
masses. As these two daughter-masses become more and more developed, the
valves of the mother-cell are pushed more and more widely apart. A new
siliceous valve is secreted by each of the two masses on the side
opposite to the original valve, the new valves being situated within the
girdle of the original frustule. When this process has been completed
the girdle of the mother frustule gives way, and two distinct frustules
are formed, the siliceous valves in each of these new frustules being
one of the valves of the mother-cell, and a newly formed valve similar
and more or less parallel to it.
During the life of the plant this process of self-division is continued
with an almost incredible rapidity. On this subject the observation of
Professor William Smith, writing in 1853, is worthy of special
notice:--"I have been unable to ascertain the time occupied in a single
act of self-division, but supposing it to be completed in twenty-four
hours we should have, as the progeny of a single frustule, the amazing
number of 1,000,000,000 in a single month, a circumstance which will in
some degree explain the sudden, or at least rapid, appearance of these
organisms in localities where they were a short time previously either
unrecognized or sparingly diffused" (_British Diatomaceae_, vol. i. p.
25).
[Illustration: FIG. 6.--Formation of Auxospores.
A. _Navicula limosa._
B. _Achnanthes flexella._
C. _Navicula Amphisbaena._
D. _Navicula viridis._]
Individual diatoms when once produced by cell-division are incapable of
any increase in size owing to the rigidity of their siliceous
cell-walls, and since the new valves are always formed _within_ the
girdle of the old ones, it would follow that every succeeding generation
is reduced in size by the thickness of the girdle. In some diatoms,
however, this is not strictly true as daughter-cells are sometimes
produced of larger size than the parent-cells. Thus, the reduction in
size of the individuals is not always proportionate to the number of
cell-divisions.
On the diminution in size having reached a limit in any species, the
maximum size is regained by the formation of an auxospore. There are
five known methods of reproduction by auxospores, but it is unnecessary
here to enter into details of these methods. Suffice it to say that a
normal auxospore is produced by the conjugation of two parent-cells, its
distinguishing feature being a rejuvenescence accompanied by a marked
increase in size. These auxospores formed without conjugation are
parthenogenetic.
_Mode of Preparation._--The Diatomaceae are usually gathered in small
bottles, and special care should be taken to collect them as free as
possible from extraneous matter. A small portion having been examined
under the microscope, should the gathering be thought worthy of
preservation, some of the material is boiled in acid for the purpose of
cleaning it. The acids usually employed are hydrochloric, nitric or
sulphuric, according as circumstances require. When the operator
considers that by this process all foreign matter has been eliminated,
the residuum is put into a precipitating jar of a conical shape, broader
at the bottom than at the top, and covered to the brim with filtered or
distilled water. When the diatoms have settled in the bottom of the jar,
the supernatant fluid is carefully removed by a syringe or some similar
instrument, so that the sediment be not disturbed. The jar is again
filled with water, and the process repeated till the acid has been
completely removed. It is desirable afterwards to boil the sediment for
a short time with supercarbonate of soda, the alkali being removed in
the same manner as the acid. A small portion may then be placed with a
pipette upon a slip of glass, and, when the moisture has been thoroughly
evaporated, the film that remains should be covered with dilute Canada
balsam, and, a thin glass cover having been gently laid over the balsam,
the preparation should be laid aside for a short time to harden, and
then is ready for observation.
_General Remarks._--Diatoms are most abundant in cold latitudes, having
a general preference for cold water. In the pelagic waters of lakes and
of the oceans they are often very abundant, and in the cold waters of
the Arctic and Antarctic Oceans they exist in prodigious numbers. They
thus form a large proportion of both the marine and the fresh-water
plankton.
Large numbers of fossil diatoms are known. Not only are these minute
plants assisting at the present time in the accumulation of oceanic and
lake deposits, but in former ages they have been sufficiently active to
give rise to considerable deposits of diatomaceous earths. When the
plant has fulfilled its natural course the siliceous covering sinks to
the bottom of the water in which it had lived, and there forms part of
the sediment. When in the process of ages, as it has often happened, the
accumulated sediment has been hardened into solid rock, the siliceous
frustules of the diatoms remain unaltered, and, if the rock be
disintegrated by natural or artificial means, may be removed from the
enveloping matrix and subjected to examination under the microscope. The
forms found may from their character help in some degree to illustrate
the conditions under which the stratum of rock had been originally
deposited. These earths are generally of a white or grey colour. Some of
them are hard, but most are soft and friable. Many of them are of
economic importance, being used as polishing powders ("Tripoli"), as
absorbents for nitroglycerin in the manufacture of dynamite
("Kieselguhr"), as a dentifrice, and more recently they have been used
to a large extent in the manufacture of non-conducting and sound-proof
materials. Most of these diatomaceous earths are associated with rocks
of Tertiary formations, although it is generally regarded that the
earliest appearance of diatoms is in the Upper Cretaceous (chalk).
Vast deposits of Diatomaceous earths have been discovered in various
parts of the world,--some the deposit of fresh, others of salt water. Of
these deposits the most remarkable for extent, as well as for the number
and beauty of the species contained in it, is that of Richmond, in
Virginia, one of the United States of America. It extends for many
miles, and is in some places at least 40 ft. deep. It is a remarkable
fact that though the generations of a diatom in the space of a few
months far exceed in number the generation of man during the period
usually assigned to the existence of the race, the fossil genera and
species are in most respects to the most minute details identical with
the numerous living representatives of their class.
(E. O'M.; G. S. W.*)
DIAULOS (from Gr. [Greek: di-], double, and [Greek: aulos], pipe), in
architecture, the peristyle round the great court of the palaestra,
described by Vitruvius (v. II), which measured two stadia (1200 ft.) in
length; on the south side this peristyle had two rows of columns, so
that in stormy weather the rain might not be driven into the inner part.
The word was also used in ancient Greece for a foot-race of twice the
usual length.
DIAVOLO, FRA (1771-1806), the popular name given to a famous Italian
brigand associated with the political revolutions of southern Italy at
the time of the French invasion. His real name was Michele Pezza, and he
was born of low parentage at Itri; he had committed many murders and
robberies in the Terra di Lavoro, but by good luck combined with
audacity he always escaped capture, whence his name of Fra Diavolo,
popular superstition having invested him with the characters of a monk
and a demon, and it seems that at one time he actually was a monk. When
the kingdom of Naples was overrun by the French and the Parthenopaean
Republic established (1799), Cardinal Ruffo, acting on behalf of the
Bourbon king Ferdinand IV., who had fled to Sicily, undertook the
reconquest of the country, and for this purpose he raised bands of
peasants, gaol-birds, brigands, &c., under the name of Sanfedisti or
_bande della Santa Fede_ ("bands of the Holy Faith"). Fra Diavolo was
made leader of one of them, and waged untiring war against the French
troops, cutting off isolated detachments and murdering stragglers and
couriers. Owing to his unrivalled knowledge of the country, he succeeded
in interrupting the enemy's communications between Rome and Naples. But
although, like his fellow-brigands under Ruffo, he styled himself "the
faithful servant and subject of His Sicilian Majesty," wore a military
uniform and held military rank, and was even created duke of Cassano,
his atrocities were worthy of a bandit chief. On one occasion he threw
some of his prisoners, men, women and children, over a precipice, and
on another he had a party of seventy shot. His excesses while at Albano
were such that the Neapolitan general Naselli had him arrested and
imprisoned in the castle of St Angelo, but he was liberated soon after.
When Joseph Bonaparte was made king of Naples, extraordinary tribunals
were established to suppress brigandage, and a price was put on Fra
Diavolo's head. After spreading terror through Calabria, he crossed over
to Sicily, where he concerted further attacks on the French. He returned
to the mainland at the head of 200 convicts, and committed further
excesses in the Terra di Lavoro; but the French troops were everywhere
on the alert to capture him and he had to take refuge in the woods of
Lenola. For two months he evaded his pursuers, but at length, hungry and
ill, he went in disguise to the village of Baronissi, where he was
recognized and arrested, tried by an extraordinary tribunal, condemned
to death and shot. In his last moments he cursed both the Bourbons and
Admiral Sir Sidney Smith for having induced him to engage in this
reckless adventure (1806). Although his cruelty was abominable, he was
not altogether without generosity, and by his courage and audacity he
acquired a certain romantic popularity. His name has gained a world-wide
celebrity as the title of a famous opera by Auber.
The best known account of Fra Diavolo is in Pietro Colletta's _Storia
del reame di Napoli_ (2nd ed., Florence, 1848); B. Amante's _Fra
Diavolo e il suo tempo_ (Florence, 1904) is an attempted
rehabilitation; but A. Luzio, whose account in _Profili e bozzetti
storici_ (Milan, 1906) gives the latest information on the subject,
has demolished Amante's arguments. (L. V.*)
DIAZ, NARCISSE VIRGILIO (1808-1876), French painter, was born in
Bordeaux of Spanish parents, on the 25th of August 1808. At first a
figure-painter who indulged in strong colour, in his later life Diaz
became a painter of the forest and a "tone artist" of the first order.
He spent much time at Barbizon; and although he is the least exalted of
the half-dozen great artists who are usually grouped round that name, he
sometimes produced works of the highest quality. At the age of ten Diaz
became an orphan, and misfortune dogged his earlier years. His foot was
bitten by a reptile in Meudon wood, near Sevres, where he had been taken
to live with some friends of his mother. The bite was badly dressed, and
ultimately it cost him his leg. Afterwards his wooden stump became
famous. At fifteen he entered the studios at Sevres, where the
decoration of porcelain occupied him; but tiring of the restraint of
fixed hours, he took to painting Eastern figures dressed in richly
coloured garments. Turks and Oriental scenes attracted him, and many
brilliant gems remain of this period. About 1831 Diaz encountered
Theodore Rousseau, for whom he entertained a great veneration, although
Rousseau was four years his junior; but it was not until ten years later
that the remarkable incident took place of Rousseau teaching Diaz to
paint trees. At Fontainebleau Diaz found Rousseau painting his wonderful
forest pictures, and determined to paint in the same way if possible.
Rousseau, then in poor health, worried at home, and embittered against
the world, was difficult to approach. Diaz followed him surreptitiously
to the forest,--wooden leg not hindering,--and he dodged round after the
painter, trying to observe his method of work. After a time Diaz found a
way to become friendly with Rousseau, and revealed his anxiety to
understand his painting. Rousseau was touched with the passionate words
of admiration, and finally taught Diaz all he knew. Diaz exhibited many
pictures at the Paris Salon, and was decorated in 1851. During the
Franco-German War he went to Brussels. After 1871 he became fashionable,
his works gradually rose in the estimation of collectors, and he worked
constantly and successfully. In 1876 he caught cold at his son's grave,
and on the 18th of November of that year he died at Mentone, whither he
had gone to recruit his health. Diaz's finest pictures are his forest
scenes and storms, and it is on these, and not on his pretty figures,
that his fame is likely to rest. There are several fairly good examples
of the master in the Louvre, and three small figure pictures in the
Wallace collection, Hertford House. Perhaps the most notable of Diaz's
works are "La Fee aux Perles" (1857), in the Louvre; "Sunset in the
Forest" (1868); "The Storm," and "The Forest of Fontainebleau" (1870)
at Leeds. Diaz had no well-known pupils, but Leon Richet followed
markedly his methods of tree-painting, and J. F. Millet at one period
painted small figures in avowed imitation of Diaz's then popular
subjects.
See A. Hustin, _Les Artistes celebres: Diaz_ (Paris); D. Croal
Thomson, _The Barbizon School of Painters_ (London, 1890); J. W.
Mollett, _Diaz_ (London, 1890); J. Claretie, _Peintres et sculpteurs
contemporains: Diaz_ (Paris, 1882); Albert Wolff, _La Capitale de
l'art: Narcisse Diaz_ (Paris, 1886); Ph. Burty, _Maitres et
petit-maitres: N. Diaz_ (Paris, 1877). (D.C.T.)
DIAZ, PORFIRIO (1830- ), president of the republic of Mexico (q.v.),
was born in the southern state of Oaxaca, on the 15th of September 1830.
His father was an innkeeper in the little capital of that province, and
died three years after the birth of Porfirio, leaving a family of seven
children. The boy, who had Indian blood in his veins, was educated for
the Catholic Church, a body having immense influence in the country at
that time and ordering and controlling revolutions by the strength of
their filled coffers. Arrived at the age of sixteen Porfirio Diaz threw
off the authority of the priests. Fired with enthusiasm by stories told
by the revolutionary soldiers continually passing through Oaxaca, and
hearing about the war with the United States, a year later he determined
to set out for Mexico city and join the National Guard. There being no
trains, and he being too poor to ride, he walked the greater part of the
250 m., but arrived there too late, as the treaty of Guadalupe-Hidalgo
(1848) had been already signed, and Texas finally ceded to the United
States. Thus his entering the army was for the time defeated. Thereupon
he returned to his native town and began studying law. He took pupils in
order to pay his own fees at the Law Institute, and help his mother. At
this time he came under the notice and influence of Don Marcos Perez and
Benito Juarez, the first a judge, the second a governor of the state of
Oaxaca, and soon to become famous as the deliverer of Mexico from the
priesthood (War of Reform). Diaz continued in his native town until
1854, when, refusing to vote for the dictator, Santa Anna, he was stung
by a taunt of cowardice, and hastily pushing his way to the voting
place, he recorded his vote in favour of Alvarez and the revolutionists.
Orders were given for his arrest, but seizing a rifle and mounting a
horse he placed himself at the head of a few revolting peasants, and
from that moment became one of the leading spirits in that long struggle
for reform, known as the War of Reform, which, under the leadership of
Juarez, followed the overthrow of Santa Anna. Promotion succeeded
promotion, as Diaz led his troops from victory to victory, amid great
privations and difficulties. He was made captain (1856),
lieutenant-colonel and colonel (1859), brigadier-general (1861), and
general of division for the army (1863). Closely following on civil war,
political strife, open rebellion and the great War of Reform, came the
French invasion of 1862, and the landing of the emperor Maximilian in
1864. From the moment the French disclosed their intentions of settling
in Mexico in 1862, Diaz took a prominent part against the foreign
invasion. He was twice seriously wounded, imprisoned on three different
occasions, had two hairbreadth escapes, and took part in many daring
engagements. So important a personage did he become that both Marshal
Bazaine and the emperor Maximilian made overtures to him. At the time of
Maximilian's death (with which Diaz personally had nothing to do) he was
carrying on the siege of Mexico city, which ended in the surrender of
the town two days after the emperor was shot at Queretaro between his
two leading generals. Diaz at once set to work to pay up arrears due to
his soldiers, proclaimed death as the penalty of plunder and theft, and
in the few weeks that followed showed his great administrative powers,
the officers as well as the rank and file receiving arrears of pay. On
the very day that he occupied Mexico city, the great commander of the
army of the east, to everyone's surprise, sent in his resignation. He
was, indeed, appointed to the command of the second division of the army
by President Juarez in his military reorganization, but Diaz, seeing men
who had given great and loyal service to the state dismissed from their
positions in the government, and disgusted at this course, retired to
the little city of Oaxaca; there he lived, helping in the
reorganization of the army but taking no active part in the government
until 1871.
On Juarez' death Lerdo succeeded as president, in 1872. His term of
office again brought discord, and when it was known that he was
attempting to be re-elected in 1876, the storm broke. Diaz came from
retirement, took up the leadership against Lerdo, and after desperate
struggles and a daring escape finally made a triumphal entry into Mexico
city on the 24th of November 1876, as provisional president, quickly
followed by the full presidentship. His term of office marks a prominent
change in the history of Mexico; from that date he at once forged ahead
with financial and political reform, the scrupulous settlement of all
national debts, the welding together of the peoples and tribes (there
are 150 different Indian tribes) of his country, the establishment of
railroads and telegraphs, and all this in a land which had been upheaved
for a century with revolutions and bloodshed, and which had had
fifty-two dictators, presidents and rulers in fifty-nine years. In 1880
Diaz was succeeded by Gonzalez, the former minister of war, for four
years (owing to the limit of the presidential office), but in 1884 he
was unanimously re-elected. The government having set aside the
above-mentioned limitation, Diaz was continually re-elected to the
presidency. He married twice and had a son and two daughters. His gifted
second wife (Carmelita), very popular in Mexico, was many years younger
than himself. King Edward VII. made him an honorary grand commander of
the Bath in June 1906, in recognition of his wonderful administration as
perpetual president for over a quarter of a century.
See also Mrs Alec Tweedie, _Porfirio Diaz, Seven Times President of
Mexico_ (1906), and _Mexico as I saw it_ (1901); Dr Noll, _From Empire
to Republic_ (1890); Lieut. Seaton Schroeder, _Fall of Maximilian's
Empire_ (New York, 1887); R. de Z. Enriquez, _P. Diaz_ (1908); and an
article by Percy Martin in _Quarterly Review_ for October 1909.
(E. A. T.)
DIAZ DE NOVAES, BARTHOLOMEU (fl. 1481-1500), Portuguese explorer,
discoverer of the Cape of Good Hope, was probably a kinsman of Joao
Diaz, one of the first Portuguese to round Cape Bojador (1434), and of
Diniz Diaz, the discoverer of Cape Verde (1445). In 1478 a Bartholomeu
Diaz, probably identical with the discoverer, was exempted from certain
customary payments on ivory brought from the Guinea coast. In 1481 he
commanded one of the vessels sent by King John II. under Diogo
d'Azambuja to the Gold Coast. In 1486 he seems to have been a cavalier
of the king's household, and superintendent of the royal warehouses; on
the 10th of October in this year he received an annuity of 6000 reis
from King John for "services to come"; and some time after this
(probably about July or August 1487, rather than July 1486, the
traditional date) he left Lisbon with three ships to carry on the work
of African exploration so greatly advanced by Diogo Cao (1482-1486).
Passing Cao's farthest point near Cape Cross (in the modern German
South-west Africa and) in 21 deg. 50' S., he erected a pillar on what is
now known as Diaz Point, south of Angra Pequena or Luderitz Bay, in 26
deg. 38' S.; of this fragments still exist. From this point (according
to De Barros) Diaz ran thirteen days southwards before strong winds,
which freshened to dangerous stormy weather, in a comparatively high
southern latitude, considerably south of the Cape. When the storm
subsided the Portuguese stood east; and failing, after several days'
search, to find land, turned north, and so struck the south coast of
Cape Colony at Mossel Bay (Diaz' Bahia dos Vaqueiros), half way between
the Cape of Good Hope and Port Elizabeth (February 3, 1488). Thence they
coasted eastward, passing Algoa Bay (Diaz' Bahia da Roca), erecting
pillars (or perhaps wooden crosses), it is said, on one of the islands
in this bay and at or near Cape Padrone farther east; of these no traces
remain. The officers and men now began to insist on return, and Diaz
could only persuade them to go as far as the estuary of the Great Fish
River (Diaz' Rio do Iffante, so named from his colleague, Captain Joao
Iffante). Here, however, half way between Port Elizabeth and East London
(and indeed from Cape Padrone), the north-easterly trend of the coast
became unmistakable; the way round Africa had been laid open. On his
return Diaz perhaps named Cape Agulhas after St Brandan; while on the
southernmost projection of the modern Cape peninsula, whose remarkable
highlands (Table Mountain, &c.) doubtless impressed him as the practical
termination of the continent, he bestowed, says De Barros, the name of
Cape of Storms (_Cabo Tormentoso_) in memory of the storms he had
experienced in these far southern waters; this name (in the ordinary
tradition) was changed by King John to that of Good Hope (_Cabo da Boa
Esperanca_). Some excellent authorities, however, make Diaz himself give
the Cape its present name. Hard by this "so many ages unknown
promontory" the explorer probably erected his last pillar. After
touching at the Ilha do Principe (Prince's Island, south-west of the
Cameroons) as well as at the Gold Coast, he appeared at Lisbon in
December 1488. He had discovered 1260 m. of hitherto unknown coast; and
his voyage, taken with the letters soon afterwards received from Pero de
Covilhao (who by way of Cairo and Aden had reached Malabar on one side
and the "Zanzibar coast" on the other as far south as Sofala, in
1487-1488) was rightly considered to have solved the question of an
ocean route round Afr ica to the Indies and other lands of South and
East Asia.
No record has yet been found of any adequate reward for Diaz: on the
contrary, when the great Indian expedition was being prepared (for Vasco
da Gama's future leadership) Bartolomeu only superintended the building
and outfit of the ships; when the fleet sailed in 1497, he only
accompanied da Gama to the Cape Verde Islands, and after this was
ordered to El Mina on the Gold Coast. On Cabral's voyage of 1500 he was
indeed permitted to take part in the discovery of Brazil (April 22), and
thence should have helped to guide the fleet to India; but he perished
in a great storm off his own Cabo Tormentoso. Like Moses, as Galvano
says, he was allowed to see the Promised Land, but not to enter in.
See Joao de Barros, _Asia_, Dec. I. bk. iii. ch. 4; Duarte Pacheco
Pereira, _Esmeraldo de situ orbis_, esp. pp. 15, 90, 92, 94 and
Raphael Bastos's introduction to the edition of 1892 (Pacheco met
Diaz, returning from his great voyage, at the Ilha do Principe); a
marginal note, probably by Christopher Columbus himself, on fol. 13 of
a copy of Pierre d'Ailly's _Imago mundi_, now in the Colombina at
Seville (the writer of this note fixes Diaz's return to Lisbon,
December 1488, and says he was present at Diaz's interview with the
king of Portugal, when the explorer described his voyage and showed
his route upon the chart he had kept); a similar but briefer note in a
copy of Pope Pius II.'s _Historia rerum ubique gestarum_, from the
same hand; the _Roteiro_ of Vasco da Gama's First Voyage (_Journal of
the First Voyage of ... Da Gama_, Hakluyt Soc., ed. E. G. Ravenstein
(1898), pp. 9, 14); Ramusio, _Navigationi_ (3rd ed.), vol. i. fol.
144; Castanheda, _Historia_, bk. i. ch. 1; Galvano, _Descobrimentos
(Discoveries of the World)_, Hakluyt Soc. (1862), p. 77; E. G.
Ravenstein, "Voyages of ... Cao and ... Dias," in _Geog. Journ._
(London, December 1900), vol. xvi. pp. 638-655), an excellent critical
summary in the light of the most recent investigations of all the
material. The fragments of Diaz's only remaining pillar (from Diaz
Point) are now partly at the Cape Museum, partly at Lisbon: the latter
are photographed in Ravenstein's paper in _Geog. Journ._ (December
1900, p. 642). (C. R. B.)
DIAZO COMPOUNDS, in organic chemistry, compounds of the type R.N.2.X
(where R = a hydrocarbon radical, and X = an acid radical or a hydroxyl
group). These compounds may be divided into two classes, namely, the
true diazo compounds, characterized by the grouping - N = N -, and the
diazonium compounds, characterized by the grouping N:.N<.
The diazonium compounds were first discovered by P. Griess (_Ann._,
1858, 106, pp. 123 et seq.), and may be prepared by the action of
nitrous fumes on a well-cooled solution of a salt of a primary amine,