Chapter IV: Front Matter (4)

The archbishop replied by excommunicating the disobedient professor. This aroused fresh opposition. Dollinger was almost unanimously elected rector-magnificus of the university of Munich, and Oxford, Edinburgh and Marburg universities conferred upon him the honorary degree of doctor of laws and Vienna that of philosophy. The Bavarian clergy invited Bishop Loos of the Jansenist Church in Holland, which for more than 150 years had existed independent of the Papacy and had adopted the name of "Old Catholic," to hold confirmations in Bavaria. The offer was accepted, and the bishop was received with triumphal arches and other demonstrations of joy. The three Dutch Old Catholic bishops declared themselves ready to consecrate a bishop, if it were desired. The momentous question was discussed at a meeting of the opponents of the Vatican decrees, and it was resolved to elect a bishop and ask the Dutch bishops to consecrate him. Dollinger, however, voted against the proposition, and withdrew from any further steps towards the promotion of the movement. This was the critical moment in the history of the resistance to the decrees. Had Dollinger, with his immense reputation as a scholar, as a divine and as a man, allowed himself to be consecrated bishop of the Old Catholic Church, it is impossible to say how wide the schism would have been. But he declined to initiate a schism. His refusal lost Bavaria to the movement; and the number of Bavarian sympathizers was still further reduced when the seceders, in 1878, allowed their priests to marry, a decision which Dollinger, as was known, sincerely regretted. The Old Catholic Communion, however, was formally constituted, with Reinkens at its head as bishop, and it still continues to exist (see OLD CATHOLICS).

Dollinger's attitude to the new community was not very clearly defined. It may be difficult to reconcile the two declarations made by him at different times: "I do not wish to join a schismatic society; I am isolated," and "As for myself, I consider that I belong by conviction to the Old Catholic community." The latter declaration was made some years after the former, in a letter to Pastor Widmann. The nearest approach to a reconciliation of the two statements would appear to be that while, at his advanced age, he did not wish to assume the responsibility of being head of a new denomination, formed in circumstances of exceptional difficulty, he was unwilling to condemn those who were ready to hazard the new departure. "By conviction" he belonged to the Old Catholics, but he never formally joined them. Yet at least he was ready to meet their leaders, to address them, and to discuss difficult problems with them. His addresses on the reunion of the Churches, delivered at the Bonn Conference of 1872, show that he was by no means hostile to the newly formed communion, in whose interests these conferences were held. In 1874 and again in 1875, he presided over the Reunion Conferences held at Bonn and attended by leading ecclesiastics from the British Isles and from the Oriental Church, among whom were Bishop Christopher Wordsworth of Lincoln; Bishop Harold Browne of Ely; Lord Plunket, archbishop of Dublin; Lycurgus, archbishop of Syros and Tenos; Canon Liddon; and Professor Ossinine of St Petersburg. At the latter of these two conferences, when Dollinger was seventy-six years of age, he delivered a series of marvellous addresses in German and English, in which he discussed the state of theology on the continent, the reunion question, and the religious condition of the various countries of Europe in which the Roman Catholic Church held sway. Not the least of his achievements on this occasion was the successful attempt, made with extraordinary tact, ability, knowledge and perseverance, to induce the Orientals, Anglicans and Old Catholics present to accept a formula of concord, drawn from the writings of the leading theologians of the Greek Church, on the long-vexed question of the Procession of the Holy Spirit. This result having been attained, he passed the rest of his days in retirement, emerging sometimes from his retreat to give addresses on theological questions, and also writing, in conjunction with his friend Reusch, his last book, _Geschichte der Moralstreitigkeiten in der romisch-katholischen Kirche seit dem sechzehnten Jahrhundert mit Beitragen zur Geschichte und Charakteristik des Jesuitenordens_ (Nordlingen, 1889), in which he deals with the moral theology of St Alfonso de' Liguori. He died in Munich, on the 14th of January 1890, at the age of ninety-one. Even _in articulo mortis_ he refused to receive the sacraments from the parish priest at the cost of submission, but the last offices were performed by his friend Professor Friedrich.

In addition to the works referred to in the foregoing sketch, we may
mention _The Eucharist in the First Three Centuries_ (Mainz, 1826); a
_Church History_ (1836, Eng. trans. 1840); _Hippolytus and Callistus_
(1854, Eng. trans., 1876); _First Age of Christianity_ (1860);
_Lectures on the Reunion of the Churches_; _The Vatican Decrees;
Studies in European History_ (tr. M. Warre, 1890); _Miscellaneous
Addresses_ (tr. M. Warre, 1894).

See _Life_ by J. Friedrich (3 vols. 1899-1901); obituary notice in
_The Times_, 11th January 1890; L. von Kobell, _Conversations of Dr
Dollinger_ (tr. by K. Gould, 1892). (J. J. L.*)

DOLLOND, JOHN (1706-1761), English optician, was the son of a Huguenot refugee, a silk-weaver at Spitalfields, London, where he was born on the 10th of June 1706. He followed his father's trade, but found time to acquire a knowledge of Latin, Greek, mathematics, physics, anatomy and other subjects. In 1752 he abandoned silk-weaving and joined his eldest son, Peter Dollond (1730-1820), who in 1750 had started in business as a maker of optical instruments. His reputation grew rapidly, and in 1761 he was appointed optician to the king. In 1758 he published an "Account of some experiments concerning the different refrangibility of light" (_Phil. Trans._, 1758), describing the experiments that led him to the achievement with which his name is specially associated, the discovery of a means of constructing achromatic lenses by the combination of crown and flint glasses. Leonhard Euler in 1747 had suggested that achromatism might be obtained by the combination of glass and water lenses. Relying on statements made by Sir Isaac Newton, Dollond disputed this possibility (_Phil. Trans._, 1753), but subsequently, after the Swedish physicist, Samuel Klingenstjerna (1698-1765), had pointed out that Newton's law of dispersion did not harmonize with certain observed facts, he began experiments to settle the question. Early in 1757 he succeeded in producing refraction without colour by the aid of glass and water lenses, and a few months later he made a successful attempt to get the same result by a combination of glasses of different qualities (see TELESCOPE). For this achievement the Royal Society awarded him the Copley medal in 1758, and three years later elected him one of its fellows. Dollond also published two papers on apparatus for measuring small angles (_Phil. Trans._, 1753, 1754). He died in London, of apoplexy, on the 30th of November 1761.

An account of his life, privately printed, was written by the Rev.
John Kelly (1750-1809), the Manx scholar, who married one of his
granddaughters.

DOLMAN (from Turk. _d[=o]l[=a]m[=a]n_), originally a long and loose garment left unfastened in front, and with narrow sleeves. It is worn generally by the Turks, and is not unlike a cassock in shape. The name was given to the uniform jacket, worn by hussars, and slung from the shoulders with the sleeves hanging loose; and it is also used for a similar garment worn by ladies, with wide cape-like arrangements instead of sleeves.

DOLNJA TUZLA, or DONJI SOLI, the capital of the Dolnja Tuzla district, in Bosnia, beautifully situated on the Jala or Julla, a small stream flowing into the Spreca, which joins the Bosna at Doboj, 39 m. W.N.W.; and on a branch railway from Doboj. Pop. (1895) 10,227; almost all, including a permanent colony of gipsies, being Moslems. Dolnja Tuzla is the seat of a district court and an Orthodox bishop; with several churches, many mosques, a hospital, gymnasium and commercial school. Besides large alkali works, it has a vigorous trade in grain, livestock, timber and coal, from the surrounding hills, where there is a colony of Hungarian miners; while the salt springs, owned by the state both at Dolnja, or Lower, and Gornja, or Upper Tuzla, 6 m. E., are without a rival in the Balkan Peninsula.

Dolnja Tuzla was called by the Romans _Ad Salinas_. Constantine Porphyrogenitus mentions it, in the 10th century, as _Salenes_; in other medieval documents it appears as _Sou_, _Sow_ or _Soli_. Its modern name is derived from the Turkish _tuz_, "salt." In 1690 the Austrians routed the Turks at Gornja Tuzla, and removed the Franciscan friars, with about 3000 other Roman Catholics, into Slavonia.

DOLOMIEU, DEODAT GUY SILVAIN TANCREDE GRATET DE (1750-1801), French geologist and mineralogist, was born at Dolomieu, near Tour-du-Pin, in the department of Isere in France, on the 24th of June 1750. He was admitted in his infancy a member of the Order of Malta. In his nineteenth year he quarrelled with a knight of the galley on which he was serving, and in the duel that ensued killed him. He was condemned to death for his crime, but in consideration of his youth the grand master granted him a pardon, which, at the instance of Cardinal Torrigiani, was confirmed by Pope Clement XIII., and after nine months' imprisonment he was set at liberty. Throughout that period he had solaced himself with the study of the physical sciences, and during his subsequent residence at Metz he continued to devote himself to them. In 1775 he published his _Recherches sur la pesanteur des corps a differentes distances du centre de la terre_, and two Italian translations of mineralogical treatises by A. F. Cronstedt (1702-1765) and T. O. Bergman (1735-1784). These works gained for him the honour of election as a corresponding member of the Academie des Sciences at Paris. To obtain leisure to follow his favourite pursuits Dolomieu now threw up the commission which, since the age of fifteen, he had held in the carabineers, and in 1777 he accompanied the _bailli_ (afterwards Cardinal L. R. E.) de Rohan to Portugal. In the following year he visited Spain, and in 1780 and 1781 Sicily and the adjacent islands. Two months of the year 1782 were spent in examining the geological structure of the Pyrenees, and in 1783 the earthquake of Calabria induced him to go to Italy. The scientific results of these excursions are given in his _Voyage aux iles de Lipari_ (1783); _Memoire sur le tremblement de terre de la Calabre_ (1784); _Memoire sur les iles Ponces, et catalogue raisonne des produits de l'Etna_ (1788) and other works. In 1789 and 1790 he busied himself with an examination of the Alps, his observations on which form the subject of numerous memoirs published in the _Journal de physique_. The mineral _dolomite_, which was named after him, was described by Dolomieu in 1791. He returned to France in that year, bringing with him rich collections of minerals. On the 14th of September 1792 the duc de la Rochefoucauld, with whom he had been for twenty years on terms of the closest intimacy, was assassinated at Forges, and Dolomieu retired with the widow and daughter of the duke to their estate of Roche Guyon, where he wrote several important scientific papers. The events of the 9th Thermidor (July 27, 1794) having restored the country to some tranquillity, Dolomieu recommenced his geological tours, and visited various parts of France with which he had been previously unacquainted. He was in 1796 appointed engineer and professor at the school of mines, and was chosen a member of the Institute at the time of its formation. At the end of 1797 he joined the scientific staff which in 1798 accompanied Bonaparte's expedition to Egypt. He had proceeded up the Nile as far as Cairo when ill-health made his return to Europe necessary, and on the 7th of March 1799 he set sail from Alexandria. His ship proving unseaworthy put into Taranto, and as Naples was then at war with France, all the French passengers were made prisoners. On the 22nd of May they were carried by ship to Messina, whence, with the exception of Dolomieu, they embarked for the coast of France. Dolomieu had been an object of the hatred of the Neapolitan court since 1783, when he revealed to the grand master of his order its designs against Malta, and the calumnies of his enemies on that island served now as a pretext for his detention. He was confined in a pestilential dungeon, where, clothed in rags, and having nothing but a little straw for a bed, he languished during twenty-one months. Dolomieu, however, did not abandon himself to despair. Deprived of writing materials, he made a piece of wood his pen, and with the smoke of his lamp for ink he wrote upon the margins of a Bible, the only book he still possessed, his treatise _Sur la philosophie mineralogique et sur l'espece minerale_ (1801). Friends entreated, but in vain, for his liberty; it was with difficulty that they succeeded in furnishing him with a little assistance, and it was only by virtue of a special clause in the treaty between France and Naples that, on the 15th of March 1801, he was released. On his arrival in France he commenced the duties of the chair of mineralogy at the museum of natural history, to which, after the death of Daubenton, he had been elected in January 1800. His course of lectures concluded, he revisited Switzerland. Returning thence he reached the residence of his brother-in-law at Chateau-Neuf, in the department of Saone-et-Loire, where he was seized with a fever, to which in a few days he succumbed, on the 26th of November 1801.

Dolomieu's geological theories are remarkable for originality and boldness of conception. The materials constituting the primordial globe he held to have arranged themselves according to their specific gravities, so as to have constituted a fluid central sphere, a solid crust external to this, next a stratum of water, and lastly the atmosphere. Where water penetrated through the crust, solidification took place in the underlying fluid mass, which enlarging in consequence produced rifts in the superincumbent rocks. Water rushing down through the rifts became decomposed, and the resulting effervescence occasioned submarine volcanoes. The crust of the earth he believed to be continually increasing in thickness, owing to the deposition of aqueous rocks, and to the gradual solidification of the molten interior, so that the volcanic eruptions and other geological phenomena of former must have been of far greater magnitude and frequency than those of recent times.

See Lacepede, "Eloge historique de Dolomieu," in _Memoires de la
classe des sciences de l'Institut_ (1806); Thomson, in _Annals of
Philosophy_, vol. xii. p. 161 (1808).

DOLOMITE, a mineral species consisting of calcium and magnesium carbonate, CaMg(CO3)2, and occurring as rhombohedral crystals or large rock-masses. Analyses of most well-crystallized specimens correspond closely with the above formula, the two carbonates being present in equal molecular proportions (CaCO3, 54.35; MgCO3, 45.65%). Normal dolomite is thus not an isomorphous mixture of calcium and magnesium carbonates, but a double salt; and any variations in composition are to be explained by the isomorphous mixing of this double salt with carbonates of calcium, iron, magnesium, manganese, and rarely of zinc and cobalt.

In crystalline form dolomite is very similar to calcite, belonging to the same group of rhombohedral carbonates; the primitive rhombohedron, _r_ (100), parallel to the faces of which there are perfect cleavages, has interfacial angles of 73 deg. 45', the angle of the cleavage rhombohedron of calcite being 74 deg. 55'. A specially characteristic feature is that this rhombohedron is frequently the only form present on the crystals (in calcite it is rare except in combination with other forms); the faces are also usually curved (fig. 1), sometimes to an extraordinary degree giving rise to saddle-shaped crystals (fig. 2). Crystals with plane faces are usually twinned, there being an interpenetration of two rhombohedra with the vertical axes parallel. The secondary twin-lamination, parallel to the obtuse rhombohedron _e_ (110), so common in calcite, does not exist in dolomite. In the degree of symmetry possessed by the crystals there is, however, an important difference between calcite and dolomite; the former has the full number of planes and axes of symmetry of a rhombohedral crystal, whilst the latter is hemihedral with parallel faces, having only an axis of triad symmetry and a centre of symmetry. This lower degree of symmetry, which is the same as that of dioptase and phenacite, is occasionally shown by the presence of an obliquely placed rhombohedron, and also by the want of symmetry in the etching and elasticity figures on the faces of the

primitive rhombohedron.

Dolomite is both harder (H. = 3-1/2-4) and denser (sp. gr. 2.85) than calcite. The two minerals may also be readily distinguished by the fact that dolomite is not acted upon by cold, dilute acids (see below, _Dolomite Rock_). Crystals of dolomite vary from transparent to translucent, and often exhibit a pearly lustre, especially when the faces are curved; the colour is usually white or yellowish.

The crystallized mineral was first examined chemically by P. Woulfe in 1779, and was named compound-spar by R. Kirwan in 1784; other early names are bitter-spar, rhomb-spar and pearl-spar (but these included other rhombohedral carbonates). The name dolomite (_dolomie_ of N. T. de Saussure, 1792) is in honour of the French geologist, D. G. Dolomieu, who in 1791 noted that certain Tyrolese calcareous rocks and Italian marbles effervesce only slightly in contact with acid; this name was for many years applied to the rock only, but was later extended to the crystallized mineral, first in the form dolomite-spar.

In the white crystalline dolomite-rock of the Binnenthal near Brieg in Switzerland beautiful water-clear crystals of dolomite are found; and crystallized masses occur embedded in serpentine, talc-schist and other magnesian silicate rocks. The best crystallized specimens are, however, usually found in metalliferous deposits; for example, in the iron mines of Traversella near Ivrea in Piedmont (as large twinned rhombohedra) and Cleator Moor in Cumberland; in the deposits of lead and zinc ores at Alston in Cumberland, Laxey in the Isle of Man, Joplin in Missouri; and in the silver veins of Schemnitz in Hungary and Guanajuato in Mexico.

Several varieties of dolomite have been distinguished, depending on differences in structure and chemical composition. Miemite is a crystallized or columnar variety, of a pale asparagus-green colour, from Miemo near Volterra in Tuscany; taraspite is a similar variety from Tarasp in Switzerland. Gurhofite, from Gurhof near Aggsbach in Lower Austria, is snow-white, compact and porcellanous. Brossite, from the Brosso valley near Ivrea in Piedmont, and tharandite, from Tharand in Saxony, are crystallized varieties containing iron. Closely related is the species ankerite (q.v.). (L. J. S.)

_Dolomite Rock._--The rock dolomite, also known as dolomitic or magnesian limestone, consists principally of the mineral of the same name, but often contains admixture of other substances, such as calcite, quartz, carbonate and oxides of iron, argillaceous material, and chert or chalcedony. Dolomites when very pure and well crystallized may be snowy white (e.g. some examples from the eastern Alps), but are commonly yellow, creamy, brownish or grey from the presence of impurities. They tend to be crystalline, though on a fine scale, and appear under the microscope composed of small sharply angular rhombohedra, with a perfect cleavage and very strong double refraction. They can be often recognized by this, but are most certainly distinguished from similar limestones or marbles by tests with weak acid. Dolomite dissolves only very slowly in dilute hydrochloric acid in the cold, but readily when the acid is warmed; limestones are freely attacked by the acid in either state. Magnesian limestones, which contain both dolomite and calcite, may be etched by exposing polished surfaces for a brief time to cold weak acid; the calcite is removed, leaving small pits or depressions. The distribution of the calcite may be rendered more clear by using ferric chloride solution. This is decomposed, leaving a yellow stain of ferric hydrate where the calcite occurred. Alternatively, a solution of aluminium chloride will serve; this precipitates gelantinous alumina on contact with calcite and the film can be stained with aniline dyes (Lemberg's solution). The dolomite is not affected by these processes.

Dolomites of compact structure have a higher specific gravity than limestones, but they very often have a cavernous or drusy character, the walls of the hollows being lined with small crystals of dolomite with a pearly lustre and rounded faces. They are also slightly harder, and for these and other reasons they last better as building stones and wear better when used for paving or road-mending. Dolomites are rarely fossiliferous, as the process of dolomitization tends to destroy any organic remains originally present. As compared with limestones they are less frequently well bedded, but there are exceptions to this rule. Many dolomites, particularly those of the north of England, show a very remarkable concretionary structure. The beds look as if made up of rounded balls of all sizes from a foot or two in diameter downwards. Often they are stuck together like piles of shot or bunches of grapes. They are composed of fibrous radiate calcite crystals, which by some kind of concretionary action have segregated from the dolomitic material and grouped themselves together in this way. Other concretions from these beds resemble bunches of corals, tufts of plants, or present various strange imitative forms.

Dolomite, unlike calcite, is not secreted by marine animals to build up the hard parts of their skeletons, and it is generally agreed also that dolomite is only very rarely and under exceptional conditions deposited directly from solution in water. On the other hand, there is much evidence to show that limestones may absorb or be partly replaced by magnesium carbonate, and the double salt dolomite substituted for calcite by one of those processes which are described as "metasomatic." Thus the Carboniferous limestones of various parts of Britain pass into dolomites along lines of joint, fissure or fault, or occasionally along certain bedding planes. At the same time the rock becomes crystalline, its minute structure is altered, its fossils are effaced, and as dolomite has a higher specific gravity than limestone, contraction results and cavities are formed. The prevalence of crystalline, concretionary and drusy structures in dolomite can thus be simply explained. The process may actually be studied in many "magnesian limestones," in which by means of the microscope we may trace the gradual growth of dolomite crystals taking place simultaneously with the destruction of the original features of the limestone. Recent investigations in coral reefs show that these changes are going on at the present day at no considerable depths and in rocks which have not long consolidated.

All this goes to prove that the double carbonate of calcium and magnesium is under certain conditions a more stable salt than either of the simple carbonates, and that these conditions recur in nature with considerable frequency. Experiments have proved that at moderately high temperatures (100 deg. to 200 deg. C.) solutions of magnesium salts will convert calcite into dolomite in the laboratory, and that aragonite is even more readily affected than calcite. The analogy with dolomitization of limestones is strong but not complete, as the latter process must take place at ordinary temperatures and approximately under atmospheric pressures. No completely satisfactory explanation of the change, from the standpoint of the geologist, has as yet been advanced, though much light has been thrown upon the problem. Many limestones are rich in aragonite, but this in course of time tends to recrystallize as calcite. Magnesium salts are abundant in sea-water, and in the waters of evaporating enclosed coral lagoons and of many bitter lakes. Calcite is more soluble than dolomite in water saturated with carbonic acid and would tend to be slowly removed from a limestone, while the dolomite increased in relative proportion. Dolomite also being denser than calcite may be supposed to replace it more readily when pressure is increased. These and many other factors probably co-operate to effect the transmutation of limestones into dolomites.

Examples of dolomitization may be obtained in practically every geological formation in which limestones occur. The oldest rocks are most generally affected, e.g. the Cambrian limestones of Scotland, but the change occurs, as has already been stated, even in the upraised coral reefs of the Indian and Pacific oceans which are very recent formations. It is very interesting to note that dolomites are very frequent among rocks which indicate that desert or salt-lake conditions prevailed at the time of their deposit. The dolomite or magnesian limestone of the English Permian is an instance of this. The explanation may be found in the fact that the waters of bitter lakes are usually rich in magnesium salts which, percolating through beds of limestone, would convert them into dolomite. Among the most famous dolomites are those of the Dolomite Alps of Tirol. They are of Triassic age and yield remarkably picturesque mountain scenery; it is believed that some were originally coral reefs; they are now highly crystalline and often contain interesting minerals and ores. The galena limestone of the North American Trenton rocks is mostly a dolomite.

Dolomites furnish excellent building stones, and those of the north-east of England (Mansfield stone, &c.) have long been regarded with great favour on account of their resistance to decomposition. They vary a good deal in quality, and have not all proved equally satisfactory in practice. Part of the Houses of Parliament at Westminster is built of dolomite. (J. S. F.)

DOLOMITES, THE, a mountain district in the South Tirolese Alps, though sometimes it is erroneously considered to form part of some other chain than the Alps. The distinguishing feature of this district is that it is composed of magnesian limestone, which rises in peaks of a most singular degree of sharpness and streaked by veins of the most startling colours. Nowadays it has become well known to tourists, who, however, keep mainly to a few great centres, though most of the more striking peaks were first ascended in the late sixties and early seventies of the 19th century by English mountaineers. Roughly speaking the Dolomite region lies between the Brenner railway from Franzensfeste to Trent (W.) and the road over the Monte Croce Pass from Innichen in the Drave valley by way of the Sexten glen and the Piave valley to Belluno and Feltre (E.). On the north it is limited by the railway line from Innichen to Franzensfeste, and on the south by the railway and road from Trent to Feltre. The highest summit is the Marmolata (10,972 ft.), but far more typical are the Sorapiss, the Cimon della Pala, the Langkofel, the Pelmo, the Drei Zinnen, the Sass Maor and the Rosengarten (see ALPS). Among the chief tourist resorts are St Ulrich (in the Groden valley), San Martino di Castrozza (near Primiero), Caprile and Cortina d'Ampezzo.

Besides the Dolomites included in the above region there are several other Dolomite groups (though less extensive) in the Alps. N.W. of Trent rises the Tosa group, while in Switzerland there are the Piz d'Aela group, S.W. of Bergun on the Albula Pass route, and the curious little group N. of the village of Splugen, besides other isolated peaks between the St Gotthard and Lukmanier Passes. In Dauphine itself (the home of the geologist Dolomieu) the mountain districts of the Royannais, of the Vercors, and of the Devoluy (all S.W. of Grenoble) are more or less Dolomitic in character.

See J. Gilbert and G. C. Churchill, _The Dolomite Mountains_ (London,
1864); Miss L. Tuckett, _Zigzagging among Dolomites_ (London, 1871);
P. Grohmann, _Wanderungen in den Dolomiten_ (Vienna, 1877); L.
Sinigaglia, _Climbing Reminiscences of the Dolomites_ (London, 1896);
_The Climbs of Norman-Neruda_ (London, 1899); V. Wolf von Glanvell,
_Dolomitenfuhrer_ (Vienna, 1898); J. Ball, _Western Alps_ (new ed.,
London, 1898, section 9, Rte. P. French Dolomites). (W. A. B. C.)

DOLPHIN, a name properly belonging to the common cetacean mammal known as _Delphinus delphis_, but also applied to a number of more or less nearly allied species. The dolphins, bottle-noses, or, as they are more commonly called, "porpoises," are found in abundance in all seas, while some species are inhabitants of large rivers, as the Amazon. They are among the smaller members of the cetacean order, none exceeding 10 ft. in length. Their food is chiefly fish, for the capture of which their long narrow beaks, armed with numerous sharp-pointed teeth, are well adapted, but some also devour crustaceans and molluscs. They are mostly gregarious, and the agility and grace of their movements in the water are themes of admiration to the spectators when a "school of porpoises" is playing round the bows of a vessel at sea.

The type of the group is the common dolphin (_D. delphis_) of the Mediterranean and Atlantic, which usually measures 6 to 8 ft. in length, and is thickest near the centre, where the back fin rises to a height of 9 or 10 in., and whence the body tapers towards both extremities. The forehead descends abruptly to the base of the slightly flattened beak, which is about 6 in. long, and is separated from the forehead by a transverse depression. The mouth is armed with sharp, slightly curved teeth, of uniform size, varying in number from forty to fifty on each side of both jaws. The aperture of the ear is exceedingly minute; the eyes are of moderate size and the blow-hole is crescent-shaped. The colour of the upper surface is black, becoming lighter on the flanks, and perfectly white below. Dolphins are gregarious, and large herds often follow ships. They exhibit remarkable agility, individuals having been known to leap to such a height out of the water as to fall upon the deck. Their gambols and apparent relish for human society have attracted the attention of mariners in all ages, and have probably given rise to the many fabulous stories told of dolphins. Their appearance at sea was regarded as a good omen, for although it presaged a tempest, yet it enabled the sailors to steer for a place of safety. The dolphin is exceedingly voracious, feeding on fish, cuttlefishes and crustaceans. On the south coast of England it lives chiefly on pilchard and mackerel, and when in pursuit of these is often taken in the nets. The female brings forth a single young one, which she nurses most carefully. Her milk is abundant and rich, and during the operation of suckling, the mother floats in a slightly sidelong position, so as to allow of the necessary respiration in herself and her young. The dolphin was formerly supposed to be a fish, and allowed to be eaten by Roman Catholics when the use of flesh was prohibited, and it seems to have been esteemed as a delicacy by the French. Among the seafaring population of Britain the name "dolphin" is most usually given to the beautifully coloured fish _Coryphaena hippuris_--the dorado of the Portuguese, and it is to the latter the poet is alluding when he speaks of "the dying dolphin's changing hues."

Many other allied genera, such as _Prodelphinus_, _Steno_, _Lagenorhynchus_, &c., are also included in the family _Delphinidae_, some of which live wholly in rivers.

Beside these there is another group of largely freshwater species, constituting the family _Platanistidae_, and typified by the susu (_Platanista gangetica_), extensively distributed throughout nearly the whole of the river-systems of the Ganges, Brahmaputra and Indus, ascending as high as there is water enough to swim in, but never passing out to sea. It is about 8 ft. long, blind and feeds on small fish and crustaceans for which it gropes with its long snout in the muddy waters at the bottom. _Inia geoffroyensis_, the single species of its genus, frequents the Amazon, and reaches an extreme length of 8 ft. It is wholly pink or flesh-coloured, or entirely black, or black above and pink beneath. A third is the La Plata dolphin, _Stenodelphis blainvillei_, a species about 5 ft. in length. Its colour is palish brown, which harmonizes with the brown-coloured water of the estuary of the Rio de la Plata. See CETACEA. (R. L.*)

DOMAT, or DAUMAT, JEAN (1625-1696), French jurisconsult, was born at Clermont in Auvergne, on the 30th of November 1625. He was closely in sympathy with the Port-Royalists, was intimate with Pascal, and at the death of that celebrated philosopher was entrusted with his private papers. He is principally known from his elaborate legal digest, in three volumes 4to, under the title of _Lois civiles dans leur ordre naturel_ (1689),--an undertaking for which Louis XIV. settled on him a pension of 2000 livres. A fourth volume, _Le Droit public_, was published in 1697, a year after his death. This is one of the most important works on the science of law that France has produced. Domat endeavoured to found all law upon ethical or religious principles, his motto being _L'homme est fait par Dieu et pour Dieu_. Besides the _Lois Civiles_, Domat made in Latin a selection of the most common laws in the collections of Justinian, under the title of _Legum delectus_ (Paris, 1700; Amsterdam, 1703); it was subsequently appended to the _Lois civiles_. His works have been translated into English. Domat died in Paris on the 14th of March 1696.

In the _Journal des savants_ for 1843 are several papers on Domat by
Victor Cousin, giving much information not otherwise accessible.

DOMBES, a district of eastern France, formerly part of the province of Burgundy, now comprised in the department of Ain, and bounded W. by the Saone, S. by the Rhone, E. by the Ain and N. by the district of Bresse. The region forms an undulating plateau with a slight slope towards the north-west, the higher ground bordering the Ain and the Rhone attaining an average height of about 1000 ft. The Dombes is characterized by an impervious surface consisting of boulder clay and other relics of glacial action. To this fact is due the large number of rain-water pools, varying for the most part from 35 to 250 acres in size which cover some 23,000 acres of its total area of 282,000 acres. These pools, artificially created, date in many cases from the 15th century, some to earlier periods, and were formed by landed proprietors who in those disturbed times saw a surer source of revenue in fish-breeding than in agriculture. Disease and depopulation resulted from this policy and at the end of the 18th century the Legislative Assembly decided to reduce the area of the pools which then covered twice their present extent. Drainage works were continued, roads cut, and other improvements effected during the 19th century. Large numbers of fish, principally carp, pike and tench are still reared profitably, the pools being periodically dried up and the ground cultivated.

The Dombes (Lat. _Dumbae_) once formed part of the kingdom of Arles. In the 11th century, when the kingdom began to break up, the northern part of the Dombes came under the power of the lords of Bauge, and in 1218, by the marriage of Marguerite de Bauge with Humbert IV. of Beaujeu, passed to the lords of Beaujeu. The southern portion was held in succession by the lords of Villars and of Thoire. Its lords took advantage of the excommunication of the emperor Frederick II. to assert their complete independence of the Empire. In 1400, Louis II., duke of Bourbon, acquired the northern part of the Dombes, together with the lordship of Beaujeu, and two years later bought the southern part from the sires de Thoire, forming the whole into a new sovereign principality of the Dombes, with Trevoux as its capital. The principality was confiscated by King Francis I. in 1523, along with the other possessions of the Constable de Bourbon, was granted in 1527 to the queen-mother, Louise of Savoy, and after her death was held successively by kings Francis I., Henry II. and Francis II., and by Catherine de' Medici. In 1561 it was granted to Louis, duke of Bourbon-Montpensier, by whose descendants it was held till, in 1682, "Mademoiselle," the duchess of Montpensier, gave it to Louis XIV.'s bastard, the duke of Maine, as part of the price for the release of her lover Lauzun. The eldest son of the duke of Maine, Louis Auguste de Bourbon (1700-1755), prince of Dombes, served in the army of Prince Eugene against the Turks (1717), took part in the War of the Polish Succession (1733-1734), and in that of the Austrian Succession (1742-1747). He was made colonel-general of the Swiss regiment, governor of Languedoc and master of the hounds of France. He was succeeded, as prince of Dombes, by his brother the count of Eu (q.v.), who in 1762 surrendered the principality to the crown. The little principality of Dombes showed in some respects signs of a vigorous life; the prince's mint and printing works at Trevoux were long famous, and the college at Thoissey was well endowed and influential.

See A. M. H. J. Stokvis, _Manuel d'histoire_ (Leiden, 1889);
Guichenon, _Histoire de Dombes_ (1863, 1872); and various works by M.
C. Guigue, including _Bibliotheca Dumbensis_ (with Valentin Smith)
(1856-1885).

DOMBROWSKI, JAN HENRYK (1755-1818), Polish general, was born at Pierszowice in the palatinate of Cracow, on the 29th of August 1755. Brought up in Saxony, he served for some years in the Saxon army; but when, in 1791, the Polish diet recalled all Poles serving abroad, he returned to his native land. Under Poniatowski, he took part in the campaign of 1792 against the Russians. In 1794 he distinguished himself under Kosciusko in the defence of Warsaw. For two years thereafter he lived in retirement, declining the offers of high ranks in their armies made to him by Russia and Prussia. He then went to Paris, and in January 1797 was authorized by the government of the Cisalpine Republic to organize a Polish legion. This task he executed at Milan. In command of his legion he played an important part in the war in Italy, entered Rome in May 1798, and distinguished himself greatly at the Trebbia (June 19, 1799), and in other battles and combats of 1799-1801. After the peace of Amiens he passed, as general of division, into the service of the Italian republic. Summoned by Napoleon in 1806 to promote a rising in Poland, he organized several divisions of Poles, and distinguished himself at Danzig and at Friedland. In 1809 he served in the Polish campaign and in 1812 he commanded a Polish division in the _Grande Armee_, being wounded at the passage of the Beresina. He fought under Marmont at the battle of Leipzig (1813), and in the following year returned to Poland. He was one of the generals entrusted by the tsar with the reorganization of the Polish army, and was named in 1815 general of cavalry and senator palatine of the new kingdom of Poland. He retired, however, in the following year, to his estates in Posen. General Dombrowski died at his seat of Wina-Gora in Posen on the 26th of June 1818. He wrote several military historical works in the Polish language.

DOME (Lat _domus_, house; Ital. _duomo_, cathedral), an architectural term, derived from a characteristic feature of Italian cathedrals, correctly applied only to a spherical or spheroidal vault, the horizontal plan of which is always a circle. It may be supported on a circular wall, as in the Pantheon at Rome; or on a drum, as in the later Byzantine churches and generally so in the Renaissance styles; or be carried over a square or polygonal area, in which case the base of the dome is connected to the lines of the main wall by pendentives, squinches, corbels or a series of concentric arches, or two of these combined. Its section may be semicircular, pointed, ovoid or segmental; in the latter case it is usually termed a cupola, although the pendentives which carry it continue, on the diagonal lines, the complete spherical dome, as in the entrance vestibule on the south side of the Sanctuary at Jerusalem, attributed to Herod, or in those crowning the bays of the Golden Gateway by Justinian. The dome may be constructed in horizontal courses, as in the "beehive" tombs at Mycenae, with joints radiating to the centre, or a compromise between the two, in a series of small segments of circles, as in the Temple of Jupiter in Diocletian's palace at Spalato, or again with the lower portion in horizontal courses and the upper portion with arches, as in the Pantheon at Rome.

The dome is probably one of the earliest forms of covering invented by man, but owing probably to its construction in ephemeral materials, such as the unburnt bricks in Chaldaea, there are no examples existing. But in a bas-relief (see ARCHITECTURE, fig. 10), brought by Layard from Kuyunjik, are representations of semicircular and ovoid domes, which show that the feature was well known in Assyria, and as they build domes of the same nature down to the present day and without centring of any kind, it suggests that they may have existed from the remotest ages. The most ancient examples in Europe are those of the "beehive" tombs at Mycenae and elsewhere in Greece, ascribed generally to the 11th century B.C. In a sense, they are not true domes, because they are built in horizontal courses of stone, which act like the voussoirs of an arch in resisting the thrust of the earth at the back. This did not exist in the Choragic Monument of Lysicrates or other circular buildings in Greece, because their vertical sections were not portions of circles. For this reason, the conical vault of the Baths in Pompeii is not a dome. The circular Laconicon in the Baths of Titus (A.D. 72) may have been domed, and the great hemicycles in the Thermae must certainly have been roofed with semi-domes.

The earliest Roman domes are those of the great circular halls at Baiae near Naples, described as temples, but really forming part of the immense bathing establishments there, the favourite place of resort of the Romans during the latter part of the Republic. The largest on the east side of the Lake of Avernus, known as the Temple of Apollo, is a circular hall with an internal diameter of 100 ft. Those of Diana, Mercury and Venus at Baiae, were 96, 66 and 60 ft. respectively. The vaults were all built in tufa with horizontal courses in brick and cement. Half of the dome of the Temple of Mercury had fallen down, showing the section to have been nearly that of an equilateral arch. From the fact that there were pierced openings or windows in all these domes, they probably constituted the _frigidaria_ of the baths.

The first example still existing in Rome is that of the Pantheon (A.D. 112), where a circular dome, 142 ft. in diameter, rests on a circular wall, its height being about equal to its diameter. The lower courses of this dome, built in the Roman brick or tile, were, up to the top of the third coffer, all laid in horizontal courses; above that, the construction is not known for certain; externally a series of small arches is shown, but they rested on a shell already built. The so-called Temple of Minerva Medica (now recognized as the Nymphaeum of the Baths of Gallienus, A.D. 366) is the next dated example. The Nymphaeum was decagonal on plan, so that small pendentives were required to carry the brick dome.

The domed Laconicon of the Thermae of Diocletian (A.D. 302) still exists as the vestibule of the church of Santa Maria degli Angeli. Of Constantine's time there are two small domed examples in the tomb of S. Costanza and the Baptistery of the Lateran, both in Rome, and one in the tomb of Galla Placidia at Ravenna (c. A.D. 450). From these we pass to the Sassanian domes at Serbistan and Firuzabad, of the 4th and 5th centuries respectively. These were built in brick and rested on square pendentives. In section they were ovoid. In Syria, the dome over the octagonal church at Esra, built in stone and dated A.D. 515, is also ovoid, its height being equal to its diameter, i.e. 28 ft. This, as well as the Sassanian domes, was built without centring. The next example is that of the church of Sta Sophia at Constantinople, the finest example existing, both in its conception and execution. It was built by Justinian (537-552) from the designs of Anthemius of Tralles and Isidorus of Miletus. The dome is 104 ft. in diameter, and is carried on pendentives over a square area. The construction is of brick and stone in alternate courses, and the lower part of the dome is pierced with forty windows, which give it an extraordinary lightness. The height from the pavement of the church to the soffit of the dome is 179 ft. No dome of similar dimensions was ever again attempted by the Byzantine architects, and the principal difference in later examples was the raising of the dome on a circular drum pierced with windows.

In order to lighten the dome erected over the church of San Vitale, at Ravenna, it was constructed with hollow cylindrical jars, fitted, the end of one into the mouth of the other; a similar contrivance was adopted in the tomb of the empress Helena (the Torre Pignatiara), the vaults of the Circus of Maxentius on the Via Appia, and the outer aisles of San Stefano, all at Rome, thus dispensing with the buttresses of Sta Sophia.

The domes of the earlier mosques in Cairo were built on the model of Sta Sophia, with windows pierced round the base of the dome and external buttresses between them; these domes were all built in brick coated over with cement or stucco. At a later date, and when built in stone, the upper portion was raised in height and terminated with a point on which a finial was placed. These are the domes inside and outside Cairo, which are carved with an infinity of geometrical patterns interwoven with conventional floral decoration. The upper portion of the dome is very thin, so that there is little weight and comparatively no thrust, and it is to these facts that we probably owe their preservation.

In India, in the "great mosque" of Jama Masjid (A.D. 1560) and the Gol Gumbaz, or tomb of Mahommed Adil Shah (A.D. 1630) at Bijapur, the domes are carried on pendentives consisting of arches crossing one another and projecting inwards, and their weight counteracts any thrust there may be in the dome. It is possibly for a similar reason that in the Jama Masjid of Shah Jahan at Delhi (1632-1638) and the Taj Mahal (A.D. 1630) the domes assume a bulbous form, the increased thickness of the dome below the haunches by its weight served as a counterpoise to any thrust the upper part of the dome might exert. The form is not much to be admired, and when exaggerated, as it is in the churches of Russia, where it was introduced by the Tatars, at times it became monstrous.

From these we pass to the domes of Perigord and La Charente, the earliest of which date from the commencement of the 11th century. Of the western dome of St Etienne at Perigueux (A.D. 14) only the pendentives remain, sufficient, however, with later examples, to show that these French domes were different from the Byzantine both in construction and form. The pendentives are built on horizontal courses of stone, and the voussoirs of the pointed arches which carried them form part of the pendentives; a few feet above the top of the arches is a moulding and a ledge, above which the dome, ovoid in section, is built. The principal examples following St Etienne are those of S. Jean-de-Cole, Cahors, Souillac, Solignac, Angouleme, Fontevrault, and lastly St Front at Perigueux, built about 1150, in imitation of St Mark's at Venice. The domes of the latter church were introduced into the old basilica about 1063, and were based on the church of the Apostles at Constantinople, which was pulled down in the 15th century, so that we have only the clear description of Procopius to go by. The domes over the north and south transepts and the choir of St Mark's are smaller than those over the nave and crossing, because they had to be fitted in between more ancient structures. The construction of the domes of St Mark's is not known, but at St Front the general design only was copied, and they built them in the Perigordian manner. The masons from Perigord are also responsible for the domes of the Crusaders' churches in Palestine and for some of the early churches still remaining in Cyprus. The domes of San Cyriaco at Ancona and Sant' Antonio at Padua were based upon those of St Mark's at Venice.

In central Italy we have the dome (elliptical in plan) of the cathedral of Pisa, and it was a favourite feature over the crossing of the churches throughout Italy, being generally carried on squinch pendentives. The domes of the baptisteries of Florence, Parma, Trieste and Piacenza, are only internal, being enclosed with vertical walls and a sloping roof. In Sicily, on account of the strong Saracenic influence, the squinches are simple versions of the stalactite pendentives described under ARCHITECTURE: _Mahommedan_ (q.v.), the earliest example being found in the church of San Giovanni-dei-Leprosi (A.D. 1072), all the domes being ovoid in section.

Except in Perigord and La Charente, domes are not found in the churches in France, but in Spain they were introduced over the crossing at Burgos, Tarragona and Salamanca cathedrals, and were made architectural features externally. This is rarely found in Germany, for although in the cathedrals of Worms, Spires and Mainz, and in the churches of St Martin and Sankt Maria im Capitol at Cologne, the crossings are covered by domes, always carried on squinch pendentives, externally they built lanterns round them.

In the Renaissance styles, the dome was at once accepted as the principal characteristic feature, and its erection over the crossing of Santa Maria del Fiore at Florence was the first important work entrusted to Brunelleschi. The dome was begun in 1422, and finished in 1431, with the exception of the lantern, begun the year of his death in 1444, and completed in 1471. The dome, which is octagonal on plan, is 139 ft. in diameter, and is built with an inner and outer casing, concentric one with the other, tied together by ribs between them: the lower portion is stone, the upper part is brick.

The double shell was also employed by Michelangelo in the dome of St Peter's at Rome, the outer shell being raised higher than the lower and connected by ribs one with the other. The diameter is 140 ft. and the construction in brick, similar to that at Florence, but the ribs are in stone from Tivoli. In both these cases the weight of the lantern was a very important consideration, and is responsible for the repeated repairs required and the introduction of additional ties.

In this respect Sir Christopher Wren solved the difficulty at St Paul's cathedral, London, in another way: he provided three shells, the lower one with an eye in the centre forming the inner dome as seen from the interior; the middle one of conical form, and the outer one framed in timber and covered with lead. The conical shell carries the lantern, the weight of which is carried direct to the base, bound with iron ties, with such additional strength as may be given by the portico round.

In all these cases these domes are built on lofty drums, so that externally they present quite a different appearance to those of the Pantheon at Rome, or Sta Sophia in Constantinople.

Of other examples, the domes of the Invalides in Paris, by Mansard (1706), and of the Pantheon by Soufflot (1735), have each three shells, the former having a graceful outline. In Spain the dome of the cathedral at Granada (1530) and the Escurial (1563); in Italy those of Sta Maria della Salute at Venice, the small example of Bramante at Todi (1480) and of the Carignano at Genoa, are worth recording, as also the dome of the Suleimanie mosque at Constantinople (1550). See plates illustrating ARCHITECTURE; and INDIAN ARCHITECTURE. (R. P. S.)