NIDIFICATION. 5: necessary warmth (about 105° F.) is secured by the bird covering the eggs with its body, 'sit- ting' upon or 'incuViating' them almost continu- ously for a length of time which in a general way is proportioned to the bird's size. No very extended and accurate observations on this point have been recorded : the best are those by Kvans in The Ibis (London) for 1891 and 1802. Broadly speaking, most of the smdll song-birds hatch their young in from 13 to 15 days, but the very smallest may take less time — the humming-bird, it is said, only 10 da.ys. In canaries, it is from 15 to 18 days; in the common fowl, it is 21 days: in the duck, it is from 28 to 30 days ; in the guinea-fowl, it is 28 or 20 days ; in the turkey, 30 days; and in the swan, from 40 to -15 days. The emeu is said to sit 50 days. Small altricial birds usually begin sitting after the first egg is laid; but game-birds and water-fowl rarely begin to sit until the whole clutch is in the nest, so that the whole brood shall hatch simul- taneously. It is in most birds the function of the female to perform the duties of incubation, during which she is to a greater or less e.tent defended, fed, and clieered by her mate. Twice or oftener each day she leaves the nest for rest and to get food, and the male takes her place for an liour or two. It sometimes happens that if she is killed, the male conchides the process of incubation and cares for the young. In some groups he does the entire duty of sitting. This seems to be universally true of the ostrich and other ratite birds, and is the practice of the godwits, phalaropes, and certain other shore-birds. Both sexes join in the care of the young at first, but in most cases their education is gradually left entirely to the mother. Nests of Mamm.^ls. Among the inammals, a 'nest' in the present sense of the word is not common. The female, when about to bring fortli young, is either already in a den or lair which has been a family residence during the winter or is permanently so, or else requires no more accommodation tlian a retired corner in the midst of a thiclcet or beneath a sheltering rock. Squir- rels, wood-rats, and mice ( qq.v. ) , however, often construct in bushes and trees, or among tall grass or low brush, globular nests of leafy twigs or of grass in which the young are born. The 'lodges' of the beaver, muskrat, coypu, and the like, else- where described, are family houses in which the protection of the young is probably the prime desideratum. Hardly different, and by no means so elaborate, are the platforms or 'nests' of the anthropoid apes, and especially of the oraiigs (see Orang-utan), where the young are born, but in which they do not long remain. There is, however, little to choose between these struc- tures, or their advantage to the young, and those of many nomadic savages, such as the aboriginal Bushmen of South Africa, the northern Austra- lians, or the Indians of the Utah Basin and des- erts of Arizona and Chihuahua. Consult standard works on zoiilog', especially Cambridge Natural Bistori/, vols, iii.-x. (London, 1898-1002) ; and Newton, 'article "Nidification," in Dictionary of Birds (London and New York, ISn.S-OfiK See also works cited under Eoc. NIEBUHR, neOioor, Bartholo Georo (177fi- 18.'?1). A German historian, critic, and philol- ogist, bom August 27, 1776, at Copenhagen, i3 NIEBXJHR. where his father, Carsten Niebuhr, then resided. He showed singular aptitude for learning in hi.s earliest youth, and his powers of acquiring knowledge kept pace with his advancing years. After preliminary education, under the superin- tendence of his father, he studied law ami plii- losophy at Kiel, and then went to Edinburgh, where he devoted himself more especially to the natural sciences. On his return to Denmark he became private secretary to the Finance Minister, Schimmelmann, and from that period held several appointments under the Danish Government, be- ing made director of the Government bank in 180-1. He entered the Prussian civil service ill 1800, and during the three succeeding years he shared in the vicissitudes which befell the Government of his chief, Count Ilardcnberg. The opening of the University of Berlin in 1810 opened a new era in the life of Niebuhr. He resigned his Government position and gave at the university a course of lectures on Roman history, which, by making known the results of the new critical methods which he had ap])lied to the elucidation of obscure historical evidence, estab- lished his position as a leader in the scientific study of history, and eli'ected an important change in historical method. In 1813 he reentered the Government service. Appointed in 1816 Prus- sian Ambassador at the Papal Court, Niebuhr was enabled to verify many of his conjectures and test his methods by the actual sources of an- cient Roman history. On his return from Rome in 1823, Niebuhr took up his residence at Bonn, where he delivered classical and archivological lectures and expositions. The Revolution of 1830 again stirred his interest in public all'airs. He died January 2, 1831. Niebuhr's scholarship was broad, vigorous, and indeiieiideiit. He was an accomplished linguist and a philosophical and scientific thinker. He was a path-breaker in the modern method of historical criticism, and while all his conclusions are not accepted to-day, he showed the way by which they might be tested in the light of more complete knowle<lge. He was the founder of the Rlieiiiisches iluseuin at Bonn. Among his important works are: Hiimischc Gc- schichte (3 vols., Berlin, 1811-32; new ed. 1873; the first two volumes translated by Hare and Thirlwall, and the third by Smith and Schmitz) ; Griechische Heroengcschichte (1842; 11th ed. 1896), written for his son Marcus; Geschichte des Zeitalters der Revolution (1845). The Kleine historische xmd philologische Schriften (1828- 43) contains his introductory lectures on Ro- man history, and man}' of the essays wliieh had appeared in the transactions of the Berlin Acad- emy. Besides these, and numerous other essays on philological, historical, and archa'ological questions, Niebuhr coiiperated with Bekker and other learned annotators in reediting the Scrip- tores Historiw Biizantiiue : he also discovered hitherto imprinted fragments of classical au- thors, as, for instance, Cicero's Orations, and portions of Gains: published the Inscripiiones yiibiensps (Rome. 1821) ; and was a constant con- tributor to the literary journals of Germany. His Lectures on Ancient Hislorit is familiar in English translation. Consult: W'inkworth, Li/e and Letters of Xiebiihr (London. 1852) ; Licber, "Reminiseences of an Intercourse with Niebuhr," in Miscellaneous ^yritings (Philadelphia, 1SS4) ; and for his biosraphv. Classen (Gotha, 187G) and Eyssenhardt (ib.,'l886).
