but the experienced horseman, even with out rising in the stirrups, by letting the back yield a little at each movement, as a bent spring yields during the motion of a carriage, can carry his head quite smoothly along.

In a general review of the skeleton, we have to remark, 1. the nice adaptation of all the parts to each other, and to the strains which they have respectively to bear; as in the size of the spinal vertebræ increasing from above downwards; the bones of the leg being larger than those of the arm, and so on. 2. The objects of strength and lightness combined; as by the hollowness of the long bones; their angular form; their thickening and flexures in particular places where great strain has to be borne; the enlargement of the extremities to which the muscles are attached, lengthening the lever by which these act, &c. 3. We have to remark the nature and strength of material in different parts, so admirably adapted to the purposes which the parts serve. There is a bone, for instance, in one place, nearly as hard as iron, where, covered with enamel, it has the form of teeth, with the office of chewing and tearing all kinds of matter used as food. In the cranium, again, bone is softer, but tough and resisting; in the middle of long bones, it is compact and little bulky, to leave room for the swelling of the muscles lying there; while, at either end, it is large and spongy, with the same quantity of matter, to give a broad surface for articulation; and, in the spine, the bodies of the vertebræ, which rest on an elastic bed of intervertebral substance, are light and spongy, while their articulating surfaces and processes are very hard. In the joints, we see the tough, elastic, smooth substance, called cartilage, covering the ends of the bones, defending and padding them, and destroying friction. In infants, we find all the bones soft or gristly, and therefore calculated to bear, with impunity, the falls and blows unavoidable at their age; and we see certain parts remaining cartilage or gristle for life, where their elasticity is necessary or useful, as at the anterior extremities of the ribs. About the joints, we have to remark the ligaments which bind the bones together, possessing a tenacity scarcely equalled in any other known substance; and we see that the muscular fibres, whose contractions move the bones, and thereby the body, because they would have made the limbs clumsy even to deformity had they all passed over the joints to the parts which they have to pull,-attach 31

VOL. XIII.

themselves, at convenient distances, to a strong cord called a tendon, by means of which, like a hundred sailors at a rope, they make their effort effective at any distance. The tendons are remarkable for the great strength which resides in their slender forms, and for the lubricated smoothness of their surfaces. Many other striking particulars might be enumerated; but these may suffice. Such, then, is the skeleton, or general frame-work of the human body-less curious and complicated, perhaps, than some other parts of the system, but so perfect and so wonderful, that the mind which can attentively consider it without emotion, is in a state not to be envied.

The living force of man has been used as a working power in various ways, as in turning a winch, pulling at a rope, walking in the inside of a large wheel to move it, as a squirrel or turn-spit dog moves his little wheel, &c. Each of these has some particular advantage; but that mode in which, for many purposes, the greatest effect may be produced, is for the man to carry up to a height his body only, and then to let it work by its weight in descending. A bricklayer's laborer would be able to lift twice as many bricks to the top of a house in the course of a day, by ascending a ladder without a load, and raising bricks of nearly his own weight over a pulley each time in descending, as he can by carrying bricks and himself up together, and descending again without a load, as is still usually done.

Reflection would naturally anticipate "the above result, independently of experiment; for the load which a man should be best able to carry, is surely that from which he can never free himself— the load of his own body. Accordingly, the strength of muscles and disposition of parts are all such as to make his body appear light to him.

The question which was agitated with such warmth some time ago, as to the propriety of making men and women work on the tread-mill, receives an easy decision here. They work by climbing on the outside of a large wheel or cylinder, which is turning by their weight, and on which they must advance just as fast as it turns, to avoid falling from their proper situation. There are projections or steps for the feet on the outside of the cylinder, and the action to the workers is exactly that of ascending an acclivity. Now, as nature has fitted the human body for climbing hills, as well as for walking

on plains, the work of the tread-mill, under proper restrictions as to duration, must be as natural and healthful as any other. Its effects have now proved it to

be so.

As animal power is exhausted exactly in proportion to the time during which it is acting, as well as in proportion to the intensity of force exerted, there may often be a great saving of it by doing work quickly, although with a little more exertion during the time. Suppose two men of equal weight to ascend the same stair, one of whom takes only a minute to reach the top, and the other takes four minutes; it will cost the first but a little more than a fourth part of the fatigue which it costs the second, because the exhaustion has relation to the time during which the muscles are acting. The quick mover may have exerted, perhaps, one twentieth more force in the first instant, to give his body the greater velocity which was afterwards continued; but the sloth supported his load four times as long.

A healthy man will run rapidly up a long stair, and his breathing will scarcely be quickened at the top; but, if he walk up slowly, his legs will feel fatigued, and he will have to wait some time before he can speak calmly.

For the same reason, coach-horses are much spared by being made to gallop up a short hill, and being then allowed to go more slowly for a little time, so as to rest at the top.

The rapid waste of muscular strength, which arises from continued action, is shown by keeping the arm extended horizontally for some time: few can continue the exertion beyond a minute or two. In animals which have long horizontal necks, there is a provision of nature in a strong elastic substance on the back, or upper part of the neck, which nearly supports the head, independently of muscular

exertion.

ANISETTE. (See Liqueur.) ANNOTTA. (See Arnatto.) ANSPACH, MARGRAVINE OF. (See Craven, Lady.)

ANTIOCH, ERA OF. (See Epoch.) ANTOMMARCHI; physician of Napoleon at St. Helena. He is a native of Corsica, who left a professorship of anatomy in Florence, in order to attend the exiled emperor. Cardinal Fesch offered him a pension; but he refused it. He attended the emperor till his last moments; and a legacy of 100,000 francs was left him in his will. He was also charged, in the

same, to open the body; but sir Hudson Lowe would not permit it. After his return to Europe, he published, in 1825, in Paris, a description of Napoleon's last moments. This work, as well as those of O'Meara and Las Cases, are important contributions to the history of the empe ror. Antommarchi afterwards practised medicine in Paris, and completed his beautiful but very expensive anatomical plates, which he had previously com menced with Morgagni in Florence. When Poland was visited by the horrors of war, he hastened thither, leaving his lucrative practice and scientific labors. With considerable trouble he reached Warsaw, where the national government gave him the direction of the medical establishments. Still more difficulties were thrown in his way on his return from Poland, especially in Hesse-Cassel, ostensibly on account of his coming from a country infested with cholera, but in reality on account of his political principles. After his return to Paris, he was near being sent by Périer to Avignon with the Poles. Towards the end of 1831, he left Paris and went to Italy. He possesses a plaster cast of Napoleon, made from a mask taken immediately after his death. APHIDES, or VINE-FRETTERS. Ants.)

(See

APLOME. (See Garnet.) ARBALIST. (See Cross-Bow.) ARBORIZATIONS. (See Dendrites.) ARCOPOLIS. (See Little Rock.) ARCTIC SEAS. (See North Polar Expeditions.)

ARGENTINE REPUBLIC. An account of this state will be found under the head of Plata, United Provinces of the.

ARQUEBUSS. (See Harquebuss.) ARROW-HEAD CHARACTER. (See Persepolis, and Writing.)

ARTIGAS. We have to add to the account given of this general, that he was retained prisoner by doctor Francia, who treated him, at the same time, with great kindness, and provided for his comfortable support. He died in 1826.

ARUNDEL, EARL OF. (See Howard, Thomas.)

ARZERUM. (See Erzerum.)
ASCITES. (See Dropsy.)
ASHBURTON, LORD. (See Dunning.)
ASNA. (See Esneh.)

ASTHMA (asthma, Latin; from douage. to breathe with difficulty); difficulty of respiration, returning at intervals, with a sense of stricture across the breast and in the lungs, a wheezing, hard cough, at first, but more free towards the

of which is different in different kinds of matter, and we explain at once various laws of chemical union. According to this view, every compound is formed by a combination of the atoms of its constituents. An atom of A may combine with 1, 2, 3, or more atoms of B-an arrangement on which depends the law of multiples. If water, for example, is composed of an atom of hydrogen and an atom of oxygen, it follows that every compound of hydrogen with an additional quantity of oxygen, must contain 2, 3, or more atoms of oxygen; some multiple in a word by a whole number of the quantity of oxygen contained in water. It is equally clear, from this view of the composition of water, that the weight of an atom of oxygen is eight times heavier than an atom of hydrogen. The relative weight of the atoms of other substances may be determined in a similar manner. Thus an atom of carbon is 6 times, an atom of sulphur 16 times, and an atom of chlorine 36 times, heavier than an atom of hydrogen; and this explains why they unite with one another in the proportions expressed by those numbers. What are called the proportional numbers are, in fact, nothing else but the relative weights of atoms. No one can suppose that the laws of chemical union are the effect of chance there must be some cause for them in the nature of the ultimate particles of matter. This cause, as we have just seen, is completely supplied by the supposed atomic constitution of bodies, which accounts for the phenomena in the most beautiful and consistent manner. So perfect, indeed, is the explanation, that the existence of these laws might have been predicted by the aid of the atomic hypothesis long before they were actually discovered by analysis. But these are not the only arguments which we at present possess in favor of the existence of ultimate indivisible particles of matter. Doctor Wollaston, in his paper on the Finite Extent of the Atmosphere (Philosophical Transactions, 1822), has defended this side of the question on a new and independent principle; and the proof he has given of the atomic constitution of bodies appears decisive. Some chemists, even without expressly adopting the atomic theory itself, have followed Mr. Dalton in the use of the terms atom and atomic weight, in preference to proportion, combining proportion, equivalent, and others of a like kind. All these appellations, however, have the same signification; and, in using the word atom, instead of the

others, it should be held in mind that it merely denotes the proportions in which bodies unite; that it is the expression of a fact which will remain the same, whether the atomic hypothesis which suggested the employment of the term be true or false. There is one circumstance which, at the first view, seems hostile to the supposed atomic constitution of matter. According to the law of multiples (see Chemical Equivalents), oxygen in the three oxides of lead is in the ratio of 1: 11⁄2 : 2; so that, if we regard the protoxide as composed of one combining proportion of lead to one proportion of oxygen, the second will contain one proportion and a half, or, according to the atomic theory, one atom and a half of oxygen. Now, though the half of a combining proportion may be admitted, the existence of half an indivisible particle of matter is inconceivable; and this circumstance would be fatal to the atomic theory, were there not some satisfactory mode of accounting for it. Several explanations might be brought forward. One of them, which has found its advocates, rests on the supposition that what is called the protoxide, is, in reality, composed of one atom of lead to two atoms of oxygen; and that the real protoxide has not yet been discovered. Another mode of accounting for the anomaly is, by regarding the present deutoxide as composed of the protoxide and peroxide combined with each other. A third method is, by doubling both elements of the anomalous compound, by which the exact ratio is preserved, and the idea of the fraction of an atom is avoided. Thus the protoxide and peroxide of iron are composed, the first, of one proportion, or 28 of metal + 8 of oxygen, and the second, of 28 of metal + an atom and a half, or 12 of oxygen; or, what amounts to the same thing, of 56, or two atoms of iron, to 24, or three atoms of oxygen. These observations prove, that the occurrence of half proportions is not inconsistent with the atomic constitution of bodies: they show that the difficulty is explicable, and probably will, in the progress of discovery, be entirely removed. In the mean time, however, it would be inconvenient to allow any speculative notions on the subject to interfere with actual practice; and, therefore, it is best at once to admit the occurrence of half proportions; and, if any one prefer the term atom to equivalent or proportion, he must submit to the somewhat jarring expression of half an atom. Mr. Dalton sup

poses that the atoms of bodies are spherical, and has invented certain symbols to represent the mode in which he conceives they may combine together. (See his New System of Chemical Philosophy.) There are several questions relative to the nature of atoms, most of which will, perhaps, never be decided. Of this nature are the questions which relate to the actual form, size and weight of atoms, and to the circumstances in which they mutually differ. All that we know with any certainty is, that their weights do differ, and by exact analysis the ratios between them may be determined. The numbers which indicate the combining proportions of bodies, are, in fact, the relative weights of their atoms.

AUK. (See Pinguin.)

AUSTEN, Jane, a gifted novelist, was born Dec. 16, 1775, at Steventon, in the county of Hants, of which parish her father was rector. Upon his death, his widow and two daughters retired to Southampton, and ultimately, in 1807, to Chawton. During her residence in the last-mentioned place, Miss Austen composed the novels, which, for ease, nature, and a complete knowledge of the features which distinguish the domestic life of the English country gentry, are very highly esteemed. The principal of these productions are Sense and Sensibility; Pride and Prejudice; Mansfield Park; and Emma. Two more were published after her death, entitled Northanger Abbey, and Persuasion, which were, however, her most early attempts. The object of Miss Austen, in all her works, was to advocate the superiority of sound principle, unsophisticated manners, and undesigning rectitude, to showy and artificial pretensions. Her discrimination was acute, her humor easy and spontaneous, and her power of creating an interest in her characters by slight and reiterated touches, extraordinary. This amiable and accomplished lady, whose personal and mental attractions were of a high order, died of a decline, on the 18th of July, 1817, in her forty-second year.

AVIARY. The aviary was common to the country-houses of the Romans, but used principally, as it would appear from Pliny, for birds destined to be eaten. Singing-birds, however, were kept by the Persians, Greeks, and also the Romans, in wicker-cages; and these utensils, no doubt, gave rise to the large and fixed cage called an aviary; but in what country, and in what age, appears uncertain. They are highly prized in China. In the

altercations which took place during lord Amherst's embassy, it was stated, on the part of the emperor, that sir George Staunton had built himself a house and an aviary. That they were in use in England in Evelyn's time, is evident from a memorandum entered in his diary, that the marquis of Argyle took the parrots in his aviary at Sayes' court for owls.-The canary, or singing-bird aviary, used not unfrequently to be formed in the opaqueroofed green-house or conservatory, by enclosing one or both ends with a partition of wire, and furnishing them with dead or living trees, or spray and branches suspended from the roof for the birds to perch on. Such are chiefly used for the canary, bullfinch, linnet, &c.-The parrot aviary is generally a building formed on purpose, with a glass roof, front and ends; with shades and curtains to protect it from the sun and frost, and a flue for winter heating. In these, artificial or dead trees, with glazed foliage, are fixed in the floor, and sometimes cages hung on them; and at other times the birds allowed to fly loose.-The verdant aviary is that in which, in addition to houses for the different sorts of birds, a net or wire curtain is thrown over the tops of trees, and supported by light posts or hollow rods, so as to enclose a few poles or even acres of ground, and water in various forms. In this the birds in fine weather sing on the trees, the aquatic birds sail on the water, or the gold-pheasants stroll over the lawn; and in severe seasons they betake themselves to their respective houses or cages. Such an enclosed space will of course contain evergreen as well as deciduous trees, rocks, reeds, aquatics, long grass for larks and partridges, spruce firs for pheasants, furze-bushes for linnets, &c. An aviary, somewhat in this way, was formed by Catharine of Russia, in the Hermitage palace. These are the only sorts admissible in elegant gardens; since nothing, to one who is not an enthusiast in this branch of natural history, can be more disagreeable than an apartment filled with the dirt and discordant music of innumerable birds; such, for example, as the large aviary at Kew. Birds from the hot climates are sometimes kept in hot-houses among their native plants, as in the large conservatories at Vienna. In this case, the doors and openings for giving air must be covered with wire cloth, and the number must not be great, otherwise they will too much disfigure the plants with their excrement.-Gallinaceous aviary. At Chick, portable no