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 which he held till his death on the 26th of September 1868. His doctor’s dissertation, De computandis occultationibus fixarum per planetas (Leipzig, 1815), established his reputation as a theoretical astronomer. Die Hauptsätze der Astronomie (1836), Die Elemente der Mechanik des Himmels (1843), may be noted amongst his other purely astronomical publications. Of more general interest, however, are his labours in pure mathematics, which appear for the most part in Crelle’s Journal from 1828 to 1858. These papers are chiefly geometrical, many of them being developments and applications of the methods laid down in his great work, Der barycentrische Calcul (Leipzig, 1827), which, as the name implies, is based upon the properties of the mean point or centre of mass (see : Universal). This work abounds in suggestions and foreshadowings of some of the most striking discoveries in more recent times—such, for example, as are contained in H. Grassmann’s Ausdehnungslehre and Sir W. R. Hamilton’s Quaternions. Möbius must be regarded as one of the leaders in the introduction of the powerful methods of modern projective geometry.

 MOCATTA, FREDERICK DAVID (1828–1905), English Jewish philanthropist, was a member of the London financial firm, Mocatta and Goldsmid, but retired from business in 1874 and devoted himself to works of public and private benevolence. Besides this he was a patron of learning and himself an author of historical works, the chief of which was The Jews and the Inquisition. On occasion of his 70th birthday, he was presented with a testimonial from more than 200 philanthropic and literary institutions. The Anglo-Jewish Historical Exhibition (1887) owed its inception to him. He bequeathed his fine library to the Jewish Historical Society of England, of which he was at one time president. This library formed the basis of the collections which are now included in the Mocatta Library and Museum, founded in his memory, and located at the University of London (University College, Gower Street).

 MOCCASIN (a North-American Indian word, of which the spelling and pronunciation vary in different dialects), a shoe made of deerskin or other soft leather. It is made in one piece; the sole is soft and flexible and the upper part is often adorned with embroidery, beading or other ornament. It is the footwear of the North American Indian tribes and is also worn by hunters, traders and settlers. In botany, the lady’s slipper is known in the United States of America, as the “moccasin flower,” from its resemblance to a shoe or moccasin. The name moccasin is also given to a venomous snake, found as far north as North Carolina and westward to the Rocky Mountains, and popularly called “cottonmouth,” from the white rim around the mouth. It belongs to the family Crotalidae, species Ancistrodon (or Cenchris) piscivorus, is about two feet long, and is often found in marshy land. It is sometimes called the water moccasin to distinguish it from the upland moccasin (Ancistrodon contortrix or atrofuscus), which is commonly called “copperhead” and is found further north in dry and mountainous regions. The name is possibly a distinct word of which the origin has not been traced.  MOCENIGO, the name of a noble and ancient Venetian family which gave many doges, statesmen and soldiers to the republic. (1343–1423) commanded the crusading fleet in the expedition to Nicopolis in 1396, and also won battles against the Genoese. While he was Venetian ambassador at Cremona he was elected doge (1414), and he escaped in secret, fearing that he might be held a prisoner by Gabrino Fondolo, tyrant of that city. He made peace with the Turkish sultan, but when hostilities broke out afresh his fleet defeated that of the Turks at Gallipoli. During his reign the patriarch of Aquileia was forced to cede his territories to the republic (1420), which also acquired Friuli and Dalmatia. Tommaso greatly encouraged commerce, reconstructed the ducal palace and commenced the library. , doge from 1474 to 1476, was one of the greatest Venetian admirals,

and revived the fortunes of his country’s navy, which had fallen very low after the defeat at Negropont in 1470. In 1472 he captured and destroyed Smyrna; the following year he placed Catherine Cornaro, queen of Cyprus, under Venetian protection, and by that means the republic obtained possession of the island in 1475. He then defeated the Turks who were besieging Scutari, but he there contracted an illness of which he died. , Pietro’s brother, who was doge from 1478 to 1485, fought against Mohammed II. and Ercole I., duke of Ferrara, from whom he recaptured Rovigo and the Polesine. was doge from 1570 to 1577. During his reign Venice lost the fortresses Nicosia and Famagosta in Cyprus. He took part in the battle of Lepanto, but after the loss of Cyprus he was forced to make peace with the Turks and to hand them back his conquests. , who flourished in the 15th and 16th centuries, was a senator of the republic and a historian; he composed a work on the league of Cambrai entitled Belli memorabilis Cameracensis adversus Venetos historiae libri vi. (Venice, 1525). Another was doge from 1700 to 1709, and his brother from 1722 to 1732. (1701–1778), who was doge from 1763 until his death, restricted the privileges of the clergy, and in consequence came into bitter conflict with Pope Clement XIII.  MOCHA STONE, a name applied to chalcedony with dendritic markings, said to have been obtained originally from Mocha in Arabia. The markings which sometimes simulate with curious fidelity the form of miniature trees and shrubs, are caused by the infiltration of solutions carrying iron and manganese, which are deposited as thin films of oxide along the cracks of the stone, producing black, brown or red dendrites, effectively disposed on a ground of grey or white chalcedony. Most of the Mocha stones of commerce are obtained from India, where they are found among the agate-pebbles resulting from the disintegration of the trap rocks of the Deccan. In recent years the formation of dendrites has been artificially effected at the agate-works of Oberstein, so as to imitate the true Mocha stones.  MOCK, an adjective meaning sham, feigned, spurious, falsely imitative. As a verb it means to deride or imitate contemptuously. The derivation of O. Fr. mocquer, mod. moquer; Ital. moccare, from which the English word is adopted, is disputed. Some authorities refer it to Ger. mucken, mucksen, to growl, grumble, which is probably echoic in origin; others to a supposed Late Lat. muccare, formed from mucus—mucus, in the sense of “to wipe the nose at.”  MOCKING-BIRD, or (as W. Charleton, J. Ray and M. Catesby called it), the popular name of birds belonging to the American sub-family Miminae, of the thrushes Turdidae, differing by having the tarsus scutellate in front, while the typical thrushes have it covered by a single horny plate. Mimus polyglottus, the northern mocking-bird, inhabits the southern part of the United States, being in the north only a summer visitant; it breeds rarely in New England, is seldom found north of the 38th parallel, and migrates to the south in winter, passing that season in the Gulf States and Mexico. It appears to be less numerous on the western side of the Alleghanies, though found in suitable localities across the continent to the Pacific coast, but seldom farther north than Virginia and southern Illinois, and it is said to be common in Kansas. J. J. Audubon states that the mocking-birds which are resident all the year round in Louisiana attack their travelled brethren on the return of the latter from the north in autumn. The names of the species, both English and scientific, have been bestowed from its capacity of successfully imitating the cry of many other birds, to say nothing of other sounds, in addition to uttering notes of its own which possess a varied range and liquid fullness of tone that are unequalled, according to its admirers, even by those of the (q.v.).

Plain in plumage, being greyish brown above and dull white below, while its quills are dingy black, variegated with white, there is little about the mocking-bird’s appearance beyond its graceful form to recommend it; but the lively gesticulations it exhibits are very attractive, and therein its European rival in melody is far surpassed, for the cock-bird mounts aloft in rapid