tion of the eggs to the warmth of the sun; birds employ the warmth of their own bodies for this purpose. The process which they use is called incubation. All known birds, with the exception of the cuckoo, discharge this office themselves. The cuckoo deposits its eggs in the nest of the hedge-sparrow and other small birds. The ostrich, contrary to the common opinion, sits upon its eggs, the male in company with several females, day and night. Among many sorts of birds, as the common hen, ducks, geese, &c., the business of incubation is confined to the female; among others, especially those which live in pairs, as the dove, lark, sparrow, &c., the male takes part. The female usually leaves the eggs for some hours, about noon, to seek food and bathe herself. In other species of birds, the male remains near the female during the process, protects her from injury, brings her food, &c. This is the case with the canary bird, goldfinch, linnet, &c. The perseverance and devotion of the female during the period of incubation is admirable. She submits to the most inconvenient postures, to avoid injuring her eggs, and forgets her food and her companions. If she is compelled by hunger to quit her post, she covers her eggs with feathers, moss, wool, &c. Birds in general become comparatively tame during this period. Others defend their nests with the greatest courage. The domestic hen boldly encounters the largest dog. Only a few birds living in a state of freedom, allow their nests to be disturbed. Many desert them entirely, if a man has displaced the eggs during their absence; for instance, the canary bird. The gradal developement of the young bird in he egg has been observed, particularly in the case of the eggs of the domestic hen. The covering of the young bird, when it first leaves the egg, is a sort of down; this is gradually superseded by feathers. The little creature remains for some hours or longer, in the nest, under its mother, till it has become accustomed to the external air. The old birds, particularly the female, now manifest the greatest care for their young, in protecting them and providing for their wants. They bring them suitable food, which, when necessary, the mother softens first in her crop. The dirt of the young is thrown out of the nest by the old birds as long as the young reniain blind. Water and marsh birds, soon after birth, leave the nest, and follow their mother into the water. The old birds teach them where to find their food. The mother protects them, takes them in stormy weather under her wings, and exposes herself to much inconvenience to save them from suffering. The time of incubation generally varies with the size of the birds. The linnet requires but fourteen days,the common hen twenty-one, and the swan forty-two days. In warın climates, the time of incubation is said to be somewhat shorter. In Africa, the hen is said to sit but thirteen days. With us, toc, in very cold weather, geese and hens are known to sit much longer than in warm. The warmth required for fecundating the eggs is about 104° Fahr. The artificial hatching of eggs is practised in Egypt. In Naples, ovens for this purpose were constructed in the 14th century. But in Egypt, this art has been carried to a high degree of perfection. The ovens intended for this purpose are made of brick, and sunk some depth in the earth. They consist of two stories, connected with each other, and divided into several apartments. In a corner of the building is an oven, which is heated daily three to four hours, for ten days in succession, with cow and camel's dung, the usual fuel of the country. The heat is regulated by the feeling of the superintendent. The temperature to be produced is compared with the warmth of baths. When the heat is too great, some passages are opened for the air. The floors of the divis ions or apartments are covered with mats, and a layer of straw thereupon, on which the eggs are laid, so, however, as not to touch each other. They are turned twice by day, and as often by night. After eight or ten days, the eggs are examined with a lamp, to ascertain the progress of the process of fecundation. Those which appear to be unfruitful are thrown away; the others, on the 14th day, are put in the upper story, On the 20th or 21st day, the young bird issues out. The owner of the oven receives a third part of the eggs for his trouble. The inhabitants of a village called Berme, in the Delta, are the persons who carry on this art throughout the country. In China, also, artificial hatching is practised. The eggs there are put in wooden boxes, which are filled with sand, and placed upon heated iron plates. Of late, a Frenchman has published a work on this subject, in which he seeks to introduce the Egyptian ovens on an im proved plan. He heats his ovens with boil ing water. INCUBUS (Latin, incubus, one who hes upon); a spirit, to whom was ascribed the oppression known by the vulgar nume of nightmare, in Greek ephialtes (from and Dopat, I leap upon). The English nightmare is from mair, an old woman or hag, in which form the spirit was generally supposed to appear, pressing upon the breast, and impeding the action of breathing. The French cauchemare or cochemare (qui couche sur) is of the same character and origin. These dæmons play an important part in the superstitions of the middle ages, having been, perhaps, not unfrequently employed, like the elder gods of Greece, to cloak the advances of earthly lovers. The nuns and other young ladies of the middle ages were not always safe from their violence or their persuasions, as numberless tales and grave histories abundantly prove. Augustin (De Civit. Dei) mentions the fact that Sylvanos, Panes, et Faunos, quos vulgo Incubos vocant, improbos sæpe extitisse mulieribus, et earum appetisse ac peregisse concubitum. The word is also used for the oppression or feeling of suffocation which sometimes comes on during sleep. The sufferer experiences a short period of intense anxiety, fear, horror, &c. ; feels an enormous weight on his breast; is pursued by a phantom, monster or wild beast, whom he cannot escape; is on the brink of a precipice, from which he cannot remove, or is, perhaps, rolling down it without being able to make any exertion for his safety, and his limbs refuse to do their othee, until he suddenly awakens himself by starting from his recumbent posture, or by a loud cry; he is then in a state of great terror, and the body is often covered with sweat. It is generally owing to repletion and indigestion, and is often superinduced by lying on the back. It is most common in those seasons of the year which most increase the volume of the fluids in spring and autumn. Homer (I. xxii. 200) and Virgil (En. xii. 908) have given striking pictures of its benumbing power, and Fuseli has represented its agonies. He is said to have eaten an immoderate supper of raw pork, for the purpose of obtaining a vivid conception of his subject. INCUNABULA (from the Latin, signifying cradle) is a term applied to those editions of books which were printed previously to the year 1500. Peignot explains it as signifying editions, qui touchent au berceau de l'imprimerie. The term is most properly confined to the period above-mentioned, because the art of printing was completely formed, in all its principal parts, in that period. Panzer's work comes down, deed, to 1536, and Mattaire's still later; but this forms no objection to our limitation, because these two writers had regard to the history of printing in general, rather than to the history of the incunabula in particular. A knowledge of them is important, as they are the best, and often the only sources, from which a minute history of the early progress of the art of printing can be drawn; but notwithstanding the investigations of bibliographers, much remains to be done in determining the particular characteristics and mutual relations of these works. Many of these works, too, are important and interesting, on account of the illustration which they afford of the history of art by their ornaments, and on account of the value of the first editions (editiones principes), of ancient and modern classics in a critical respect. We shall here treat of them in reference to their value to professed collectors.-1. The first beginnings and attempts at printing will naturally be objects of their search, among which are the xylographic specimens, and the earliest impressions bearing date, which begin with the indulgences of Nicolas V, 1454; although the oldest printed book, whose date is undoubted, is the Psalter of 1457.-2. Next to these are the first impressions of particular countries and places, which are generally not less rare than the preceding.-3. The first books printed in a particular language or with certain types. The oldest impressions are in the Gothic type, as it is called; the round or Roman character, which afterwards became the most common, particularly in Italy, came into use somewhat later. Single Greek words, cut in wood, were first used in 1465, in Cicero's De Officiis, and in the edition of Lactantius of the same year. The first book printed entirely in the Greek type, was Laskaris's Greek Grammar, which appeared at Milan, 1476. 4. Editions from those presses which did not do much, and, from the more fertile presses, those editions which are peculiarly rare; e. g., the Mentel editions of the old Roman classics.-5. Editions in which certain typographical improvements were first introduced; as J. Nideri Præceptorium divinæ Legis (Cologue, Koelhof, 1472, folio), the first book printed with signatures; Sermo ad Populum prædicabilis (Cologne, ther Hernen, 1470, 4to.), the first with the pages numbered; Cicero De Officiis (1465), the first in quarto; and the Officium Beatæ Mariæ Virg. (Venice, Jenson, 1473, 32mo.), the first in the smallest form. Title pages first appeared after the year 1485.-6. Editions with the first, or with remarkable attempts to apply the arts to the ornamenting of books. The first printed book with copper-plates is Antonio da Siena's Monte Santo di Dio (Florence, 1477, fol.). The most remarkable wood-cuts, of which the Strasburg printer Grüninger was very fond, are to be found in German and Italian editions. In this division may also be included copies with excellent miniature engravings.-7. Single copies which are celebrated on account of some particular circumstances; e. g., those printed on parchment and with gold letters (of which we have some from the 15th century), &c. Of the impressions on parchment, on which whole editions were at first printed, and the greater part of the copies, even of later editions (e. g., of the Latin Bible of 1462), those are particularly sought after, which issued from presses that printed but little on parchment; e. g. Schweinheim and Pannarz at Rome, by whom only six parchment editions are known to have been published.-8. Finally, there are some particular collections or scries, which collectors pride themselves particularly on possessing; e. g., the six Greek works (Anthologia, Apollonius Rhodius, Euripides, Callima chus, Gnoma, Musaus), printed in capitals by Alopa at Florence (1494-96), or the Greek works printed at Milan with a very round type, of which Laskaris (1476) is the first, and Suidas (1499) the last. Editions from celebrated presses of the 15th century are also highly valued; e. g., those of Schweinheim and Pannarz, and the English printers Caxton, Pynson and Wynkyn. (For information concerning the incunabula, see Panzer's Annales Typographici, together with his Annals of German Literature, which together contain the most complete catalogue, to the year 1536.) Mattaire's Annals are far less complete, but they come lower down, and enter rather more into details. Serna Santander's Dictionnaire Bibliographique choisi du 15 Siècle (Brussels, 1805, 3 vols.) is a useful work on the most interesting incunabula. It contains much information on the incunabula of Spain and the Low Countries, which is wanting in Panzer. Besides these works, we may find accounts of particular incunabula, in the local histories of printing (especially in Audiffredi's works on Roman and Italian printing), in the accounts of some particular printers of the 15th century (Guttenberg, Jenson, Aldus, Giunti), and in the works which treat of the incunabula of some single libraries, as those of Fossi, Dibdin (Bibliotheca Spenceriana), &c. 47 VOL. VI. INDEPENDENCE, in politics; the sove. reignty of a people or country, as distinguished from a former dependence upon another country. When a successful attempt is made, by a portion of a people subject to a common government, to establish a separate government for itself, the struggle is generally closed by the acknowledgment of its independence on the part of the government from which it has seceded, though, in some cases, a complete separation is effected without any such acknowledgment, when the old government is too weak to undertake any thing effective against the revolted provinces or colonies, and yet will not formally renounce its authority over them. In such a case, it cannot be supposed that such an acknowledgment is necessary to entitle the new state to be treated by other powers as independent. This was the case with the United Provinces and Spain, the latter not acknowledging the former for a long serics of years. The South American republics, too,have not yet been acknowledged by Spain, but no one can doubt their independence. The just rule would seem to be, that a colony or province is independent whenever it declares itself so, and is able to maintain its independence, or is left in undisturbed enjoyment of it. In a complicated political system, like that of Europe, the acknowledgment of independence on the part of the old government, is diplomatically important; and without it, other European states are averse to enter into political relations with the new state. The government of the U. States, on the other hand, considers only whether the revolted country is in fact independent; and in their own casc, their diplomatic agents called upon foreign powers to acknowledge the independence of the revolted colonies, before any such acknowledgment was made by England. (See Lyman's Diplomacy, also the Diplomatic Correspond. of the Am. Revolution.) It hardly needs to be mentioned, that no sovereign power is obliged to wait for the acknowledging of independence by the mother country, because the idea of sovereignty excludes such an obligation. The political era of the U. States, in public doc. uments, is the year of their independence (July 4), 1776; accordingly, the present is the 55th year of American independence. INDEPENDENTS; a Protestant sect in England and Holland,which originated towards the end of the 16th century, during the reign of queen Elizabeth. The Independents declared the ceremonies of the Anglican church popish abuses, and hea thenish. They agreed only in this point, the orders of the papal authorities, it is INDEX. A scientific work becomes termed Inder expurgatorius, and, in the sellers, whose publications are altogether INDIA; THE INDIES. This name has name is derived by us from the Greeks, |