BIOT BIOT, JEAN BAPTISTE, a French physicist and astronomer, born in Paris, April 21, 1774. He entered the artillery, but forsook the service for science, and, in 1880, became Professor of Physics in the College de France. Along with Arago he was (1806) sent to Spain to carry out the measuring of a degree of the meridian, and, in 1817, he visited England, and went as far N. as the Shet- land Islands, in order to make observa- tions along the line of the British arc of meridian. His most valuable contri- butions to science are on the polarization of light, for which he received the Rum- ford gold medal in 1840. On astronomy he wrote: "Researches into Ancient Chi- nese Astronomy" (1840), and "Studies in Indian Astronomy" (1862). His works on physics are "Elementary Trea- tise on Physical Astronomy" (1841- 1857). In 1849 Biot was made a com- mander of the Legion of Honor; he was also a member of the French Academy. He died in Paris, Feb. 3, 1862. BIOTITE, a hexagonal and an opti- cally uniaxial mineral, formerly called magnesia mica, hexagonal mica, and un- iaxial mica J named after Jean Baptiste Biot. It exists in tabular prisms, in dis- seminated scales, or in massive aggre- gations of cleavable scales. Color: sil- very-white, rarely bottle green, and by transmitted light often fiery red. BIPED, a descriptive term, sometimes applied to man, but more frequently to birds. It may be used in two ways— (a) in reference to habit only (physio- logical), when animals use only their two hind limbs for moving along the ground — e. g., man, kangaroo, bird; (b) in reference to anatomy (morphology), when the typical number of four limbs is reduced to two. Thus among mam- mals the order of whales (cetacea) is marked by the absence of hind limbs; among birds the fore limbs are consid- erably reduced in the running birds of the ostrich sub-class, and especially in the New Zealand kiwi (apteryx) ; among rentiles, some serpents (e. g., pifthons), retain traces of hind legs, while all the others have lost both paii's, and a few lizards have either only hind feet (pseu- dopiis, ophiodes) , or only fore feet (chi- rotes) ; among amphibians, a few (e. g., siren) have only fore feet; and the same is true of numerous fishes (e g., among sihaHdae), and especially of those which live to a large extent in mud. BIQUADRATIC EQUATION, in al- gebra, an equation raised to the fourth power, or where the unknown quantity of one of the terms has four dimensions. An equation of this kind, when complete, is 86 SIBD of the form a;* + Aa;' + Ba:*4-Ca:4- D=0, where A, B, C and D denote any known quantities whatever. BIRCH, the English name of the trees and shrubs belonging to the botanical genus betula. The common birch (betula a/6a) has ovate-deltoid, acute, doubly ser- rate leaves. Its flowers are in catkins, which come forth in April and May. It grows best in healthy soils and in Alpine districts. The drooping or weep- ing birch {B. pendula) is a variety of tliis tree. It grows wild on the European continent and in Asia. The wood of the birch is tough and white. It is used for making brooms; it is often burned into charcoal. The oil obtained from the white rind is used in tanning Russia leather. The Russians turn it to account also as a v€ inifuge and as a balsam in the cure oi w^ounds. In some countries the bark of the birch is made into hats and drinking cups. The B. nana, or dwarf birch, grows in the High- lands of Scotland, in Lapland, etc. It is a small shrub, one or two feet high. The Laplander uses the wood for fuel, and the leaves, spread over with a reindeer's skin, for a bed. B. lenta is the ma- hogany birch, mountain mahogany, sweet birch, or cherry birch of North America. Its leaves are fragrant, and have been used as a substitute for tea. The canoe birch, of which the North American Indians constructed theii port- able canoes, is the B. papyracea. BIRCH, SAMUEL, an English Orien- talist, bom in London, Nov. 3, 1813. He entered the British Museum as Assistant Keeper of Antiquities, in 1836, and ulti- mately became Keeper of the Egyptian and Assyrian Antiquities. He was espe- cially famed for his capacity and skill in Egyptology, and was associated with Baron Bunsen in his work on Egypt. His principal works include "Gallery of Antiquities" (1842); "Catalogue of Greek Vases" (1851) ; "Ancient Pottery" (1858); "Egyp', from the Earliest Times" ri875). He edited "Records of the Past," from 1873 to 1880. He died Dec. 27, 1885. BIRD, the English designation of the aves, the second class of the sub-king- dom vertebrata, standing between the mammalia (mammals) above, and the reptilia ^reptiles) below. While in their warm blood they are more closely akin to the former than to the latter, they approach the latter rather than the former in various points of anatomical structure, especially in their lower limbs. They agree also with reptiles, amphibia and fishes in being oviparous, while the mammalia bring forth their young alive
