which is continually impelled by some power towards a fixed point out of its original direction, is obliged to describe a curvilinear path round this point. A stone, slung round by a string, moves in a circle, because it is drawn toward the hand in every point of its path. The moon moves in a circle round the earth, because it gravitates towards the earth, and is thus drawn from the rectilinear direction, which it would otherwise pursue. In such cases, the point to which the body constantly tends, is called the centre of the forces; the force itself, by which it is impelled, is called the centripetal force; that by which it strives to fly from the centre is called the centrifugal force; and the motion which is produced by these two forces, the circular motion. All the planets in the solar system are carried round the sun, and the satellites round their planets, by these forces. (See Central Forces.)-The theory of circular motion is a subject of celestial mechanics, on which Newton composed his Principia Mathematica Philosoph. Natural. and Laplace his Mécanique Celeste, &c. As the model of a concise and beautiful exposition, we recommend the article under this head in Gehler's Physikalisches Wörterbuch (Dictionary of Natural Philosophy).

CIRCULAR SAWS, which revolve upon an axis, are preferable to straight saws, because they act continually in the same direction, and no force is lost by a backward stroke. At the same time, they can work with greater velocity, and, therefore, cut more smoothly. Their size, however, is limited, because they waver and bend out of the proper plane if made too large, and if they were made so as not to waver, they would be too thick. Slitting of timber, therefore, is not often performed with them, but they are much used for cutting thin layers of mahogany for veneering, for, in this case, the saw can be sufficiently strengthened towards the centre. Great velocity increases much the steadiness of a circular saw.

CIRCULATING MEDIUM. The expression circulating medium is now much more frequently used than formerly. It means the medium of exchanges, or purchases and sales, whether this medium be gold or silver coin, paper, or any other article, as oxen, tobacco, iron, slaves, usually employed in any place as the measure of the values of other articles, and is thus of a more comprehensive signification than the term money, which, though it applies to gold and silver coin, paper currency, and some other of the

various articles used for the above purpose, does not comprehend them all, since oxen, which have, by some nations, at some periods, been adopted as the measure of the comparative values of articles of commerce, would hardly be considered as coming under the denomination of money. It is hardly possible to imagine a people to be without a circulating medium of some description; and, accordingly, we find all the tribes of savages hitherto discovered referring to some article in estimating the value of the various commodities which compose their capital. Captain Franklin says, the Krees Indians use beaver skins as their medium, and estimate the value of things by a certain number of their skins. The people of Virginia, in the earlier periods of their colonial history, estimated value by pounds of tobacco. In some parts of Africa, a species of small shells, cowries, are the medium of exchanges. But from the earliest times, the precious metals, where they could be had, have been preferred for this purpose, because their weight, fineness, and, consequently, value, could be more accurately ascertained than those of any other article, and thus comprise a sufficient value in a small compass and weight to be a convenient medium. Many species of precious stones comprise a greater value in the same bulk and weight than either gold or silver, but their value cannot be so precisely estimated, nor are they found in sufficient quantities. Platina would be as convenient a medium as either gold or silver, provided it should continue to retain its present value; but it has not as yet been produced in sufficient abundance. It is one essential quality of a circulating medium, that it should have an intrinsic marketable value. Gold and silver, for instance, besides answering as a medium, have as positive a market value as iron, tin, leather or corn. This value is derived from their utility in the useful and ornamental arts; and it may be more precisely ascertained than the value of most other articles, since an agreement for a certain number of beaver skins, a certain quantity of tobacco, and still more for a certain number of cattle, admits of some doubt and dispute as to the quality; but an agreement for a certain weight of gold, of given fineness, admits of no dispute; it can be reduced to the utmost certainty. But we see other kinds of currency, which apparently answer the purpose of a circulating medium, and which have very little value. A small piece of paper, not worth intrinsically one cent, passes for many

thousand dollars; and this sometimes leads people into the mistaken notion that intrinsic value is not an essential quality in the public currency. But we must look at what is printed or written on this paper, to learn why it passes for currency. It bears a promise that the holder shall be entitled to a certain number of dollars; of course, a certain quantity of gold and silver, of a certain fineness. If this promise is valid, and will be kept, then the real medium is gold and silver, though this gold and silver may be locked up in a bank. But it may be said, that there is not, in the banks, where bank paper circulates, and, perhaps, not in the community, more than one dollar in silver or gold for four dollars promised in the paper in circulation. How then can four dollars of paper be redeemed by one of silver? This is very easy. One holder of a paper dollar demands the silver at the bank, and passes it off, or keeps it in his purse. Now if the bank can induce this person, or the one to whom he passes the dollar, to let them have it again, that is, to loan it to them, or to take something in exchange for it, they can then, with the same silver dollar, redeem the second paper one, and so on. Thus a bank that has capital, and a good credit, will be always able to reclaim and use the same specie successively to redeem its paper, and, if it be skilfully conducted, it will always be able to command it as fast as its bills can be collected and presented for payment. A community, therefore, which only uses specie and redeemable paper as currency, has, to all practical purposes, a specie medium. The paper is, in short, so much specie, for all practical purposes, for it will command gold and silver. Here, then, is evidently an advantage gained; for, if a bank, by putting one dollar in its vaults, can loan out four dollars on interest, it makes a great income on its capital, while the community loses nothing, but gains, rather; for this paper is much more convenient for transportation, and equally convenient in all other respects. It is a great object in every community to gain this advantage, arising from multiplication of money. Individuals, if not prohibited by the laws, will soon issue their paper money, and many of them make promises of paying dollars, which they cannot fulfil, and thus the public be defrauded. On the other hand, the government often makes the bubble by the issue of paper money, or promises of payment never to be fulfilled. There has rarely, if ever, been an instance of a government issuing

paper money, and redeeming it punctually, and to its full nominal amount. Innumerable issues of this sort of circulating medium were made by the American colonies before the establishment of the independence of the U. States; and, during the war of independence, the country was inundated with what was called continental money, which was never redeemed. Russia and Austria have this species of currency in circulation, always depreciated, as is usual with such money. Formerly, the sovereigns of Europe had a practice of debasing the current coin, when they wished to levy a tax in disguise, so as to make the copper, with which they alloyed the silver, pass as of the value of silver. But, in modern times, instead of debasing the coin, the usual resort is to a government bank or to government paper. Government paper, issued as the ordinary currency, usually proves to be a bubble. And it may be taken for a general rule, that no currency is safe which is not of an intrinsic value, or is not based upon capital sacredly pledged to its redemption. The question then recurs, why the government may not pledge a certain amount of capital for the redemption of its paper. The reason is, that this capital must be managed, and a vast deal of skill and economy is requisite in managing a redeemable paper currency; and of all managers, the agents of a government are the least thrifty and economical. Besides, the government will ruin the credit of its own paper by excessive issues in its exigencies in times of war, when the effects of a destruction of its credit are the most disastrous. The government, therefore, ought never to trust itself to be a banker, or to issue paper money, except in desperate circumstances or pressing exigences, when no other measure can be resorted to, and when what would otherwise be wrong and dishonest is excused for the sake of preventing the greatest national calamities. If, then, neither the government nor individuals can safely supply a circulating medium of promises, what system can be safely adopted, which shall afford all the advantages of a multiplication, in effect, of the medium of intrinsic value, namely, the gold and silver? Undoubtedly the system of bank circulation, whereby a certain capital is sacredly pledged to the redemption of the promises of payment of money made in the circulating bills. A well contrived, skilfully conducted system of banking, connected with one of circulation, is one of the greatest triumphs of national economy. The

interest, as well as the reputation of individuals, is thus pledged in support of the system, and in furtherance of the general industry and prosperity. But shall individuals reap all the advantages of the practical multiplication of capital in consequence of supplying a currency based upon, but not consisting exclusively of specie? By no means. The government may indirectly reap greater advantages from this system, than they possibly can from an attempt at becoming themselves bankers for the community, by sharing the profits with those who actually conduct the business. It is one of the proper and most important functions of the government to regulate the currency. It is bound to interfere, with proper restrictions, for preventing the frauds and bubbles to which individual enterprise and speculation inevitably lead if let loose in the career of credit; and it has a profit, in so doing, by reaping some of the advantages of a bank circulation, and thus gaining an income without, in fact, levying a tax. Thus, if, as in some of the U. States, the circulation of the notes of individuals, as a currency, is prohibited, and certain institutions have a right by charter to supply the currency by an issue of their bank notes, on paying to the government a certain bonus, as a certain per cent. on their capital, or the amount of the bills which they keep in circulation, or the amount of the dividends made on their stock, or on undertaking, as the bank of the U. States does, to render certain services in collecting the revenue and making remittances, the government derives a revenue from its right to regulate the currency; and yet no one, in fact, pays this amount to the government as a tax, for the banks which pay it receive a consideration in the privilege of supplying the currency. As long as the government does not bear oppressively upon this species of monopoly, by attempting to levy an excessive tax for the privilege, and thus discouraging it, a liberal income may be derived from the substitution of promises on paper, instead of gold and silver, for the ordinary purposes of circulation and exchange, and, at the same time, such guarantees may be provided as to prevent abuse and fraud, and render this currency as safe as that of specie.

CIRCULATION OF THE BLOOD. (See Physiology.)

CIRCUMCISION; the custom prevailing among several Eastern nations of cutting off the prepuce of the virile member. The most ancient nation among whom

this custom prevailed was the Egyptians; and we find it still among the aborigines of Egypt, even among the Christian Copts (q. v.), and the Abyssinians (q. v.), who profess Christianity, and other African nations, who seem to have received it, like the Abyssinians, from the Egyptians. The Jews perform this ancient ceremony, by which the descendants of Abraham were to be distinguished from other nations, as a rite instituted by God, on the eighth day after the birth. The circumcised person is, as it were, naturalized by this ceremony, or introduced among the people of God. Moses found it among the nation, and confirmed it. The Mohammedan circumcision is probably an ancient Ishmaelite custom, which the Ishmaelites and the Israelites received from their common father, Abraham. The Koran of Mohammed did not introduce circumcision; it was already in use among his nation, and was introduced by them, with Islamism, as a sacred rite, into all countries where their religion was received. The original object of this custom was probably the promotion of cleanliness, which is doubly necessary among the inhabitants of hot countries, for the prevention of many diseases; but it is a mistake to suppose that it increases fertility. There is also a kind of circumcision, or excision, performed on the female sex. In Egypt, Mohammedan maidens are often circumcised; and the Abyssinians circumcise both sexes. The word circumcised is often used in the Old Testament to denote the Jews.

Circumcision is also the name of a feast, celebrated on the first of January, in commemoration of the circumcision of our Savior. The day was anciently celebrated as a fast, in opposition to the customs of the pagans, who feasted on it in honor of the god Janus.

CIRCUMNAVIGATORS. Magellan, a Portuguese, was the first of those intrepid men, who, following in the path of Columbus, traversed the ocean from the east to the west, and, pursuing this direction, at last returned to their country. He circumnavigated the world in 1519-21. In his passage through the straits of Magellan, or round cape Horn, into the southern seas, he was followed by the Spaniards (Fuca, Mendaina, Quiros, and others, down to Malaspina), by the French (Bougainville, La Peyrouse, q. v., and others, down to Freycinet, q. v.), by the Dutch (Baarents, Heemskerk, Hertoge, Tasman, Roggewein), by Englishmen and Russians (from Deschneff to Krusenstern,

and Otto von Kotzebue, q. v.), and, lastly, by North Americans. The English, as was to have been expected, have made the most numerous and important voyages round the world. Fifty years after Cabot, Hugh Willoughby (1553) reached Nova Zembla, on his northern expedition. All attempts since made to enter the Pacific by a north-eastern or north-western passage have been fruitless. (See Expeditions to the North Pole.)-But the 11 voyages to the north-east and north-west by Frobisher, Gilbert, Davis, Weymouth (1591), and several other navigators, were important from the discoveries of new lands and productive fisheries, to_which they led. At the same time, Francis Drake made a voyage round the earth. Cavendish, Chidley and Hawkins followed their great predecessors to the south, but less successfully. Amongst the bold navigators who undertook great expeditions in the 17th century, Hudson, Baffin, Dampier, Halley and Woods Rogers, were distinguished by the importance of their discoveries. Woods Rogers proceeded to 62° 53′ S., and the Russian captain Bellinghausen to 70°, in the year 1820. (Rogers brought Alex. Selkirk, the reputed Crusoe, home with him.) 30 years after Rogers, lord Anson (1741-44) made a voyage round the world. With him commences a great era in the discoveries in the South seas, embracing the entire Polynesia. Then followed the voyages of discovery by Carteret and Wallis (1767). The voyages of Cook, beginning in 1770, made a new era in circumnavigation. At last, Vancouver made geographers and navigators well acquainted with the north-western coast of America. (See Kotzebue, Otto von; Krusenstern, and Voyages.) The latest Voy. autour du Monde is that of captain Duperrai, in the Coquille, made by command of Louis XVIII, in 1822-25(6 vols. 4to., with an atlas of 375 pages, published in numbers, Paris, 1828).

CIRCUMVALLATION, or LINE OF CIRCUMVALLATION, in military affairs, implies a fortification of earth, consisting of a parapet and trench, made round the town intended to be besieged, when any molestation is apprehended from parties of the enemy which may march to relieve the place.

CIRCUS, among the Romans; an oblong building without a roof, in which public chariot-races and exhibitions of pugilism and wrestling took place. It was rectangular, except that one short side formed a half circle; the entrance was at the opposite end. Within, on each side

of the entrance, were six arcades (carceres), where the chariots stood. On both the sides, and on the semicircular end, were the seats of the spectators, rising gradually one above another, like steps, and resting on strong arches. At the foot of the seats there was a broad ditch, called euripus, to prevent the wild beasts from leaping among the spectators. Within was an open space (arena), covered with sand, where the games were exhibited. This space was divided lengthwise into two parts by a wall (spina), 12 feet thick and 6 high, adorned with little temples, altars, statues, obelisks, pyramids and conical towers. Of these last (meta) there were three at each end, which served as goals, round which the circuits were made. By the first meta, opposite the curved end of the circus, there were seven other pillars, with oval balls (ova) on their summits. One of these balls was taken down for every circuit. On the outside, the circus was surrounded with colonnades, galleries, shops and public places. The largest of these buildings in Rome, the circus maximus, was situated in the 11th district of the city, which was thence sometimes called circus maximus, and on the spot where Romulus exhibited the games at which the Sabine women were carried off. Tarquinius Priscus projected the plan of this building, and some of the wealthy senators completed it. The ludi magni were celebrated in it. Dionysius of Halicarnassus gives its length at 9331 feet, and the breadth at 2187 feet. According to Pliny, it was capable of containing 260,000, and according to Aurelius Victor, 385,000 spectators. Julius Cæsar enlarged and ornamented it. Under Nero, it was burnt, and under Antoninus Pius pulled down. Trajan rebuilt it, and Constantine made further additions to it. At present, but few vestiges of it remain. The circus of Caracalla, in the first district of the city, is in the best preservation. (See Hippodrome.)

Circus, Games of the (so called from the circus (q. v.), particularly the circus maximus, where they were exhibited). Romulus celebrated similar games in honor of Neptune. Afterwards, by the mutual rivalry of the adiles, their splendor was increased. Under the emperors, they_attained the greatest magnificence. The principal games of the circus were the ludi Romani or magni, called, also, from an epithet of Cybele, megalenses, which were celebrated from the 4th to the 14th of September, in honor of the great gods, so called. The passion of the people for

these shows appears from the cry with which they addressed their rulers-Panem et circenses! (Bread and the games!) A splendid procession, or pompa, opened the festival. The images of the great gods were carried to the temple of Jupiter, on the Capitoline mount; the procession moved from this temple through the forum, and the street called Velabrum, to the circus maximus. The chief magistrate led the procession. Before him was carried the image of the winged goddess of Fortune (Fortuna alata). Then came the images of Jupiter, Juno, Minerva, Neptune, Ceres, Apollo, Diana; after the death of Julius Cæsar, his image was introduced, and in later times, perhaps, those of the deified emperors also. These images were in splendid covered chariots, drawn by horses or mules, stags, camels, elephants, also sometimes by lions, panthers or tigers. After the pompous procession of gods followed rows of boys, who had lost either father or mother, and who led the horses to be used in the races. After these followed the sons of the patricians, from 15 to 16 years of age, armed, part on horseback, part on foot. After these came the magistrates of the city and the senate. The sons of knights, on horseback and on foot, brought up the rear. Then followed the chariots and horses destined for the races, and the different athlete, as pugilists, wrestlers, runners, all naked, except a covering about the loins. In this procession were included the dancers, youths and boys, arranged in rows, according to their age. They wore violet-colored garments, with brass belts, and carried swords and short spears. The men wore helmets. Each division was preceded by a man who led the windings of the dance. The musicians followed, including a number of persons dressed like Sileni and Satyrs, who, with large wreaths of flowers in their hands, exhibited various sportive dances, with a company of musicians behind them. To this exhibition of wild, unrestrained joy, succeeded the religious pomp. First came the Camilli,-boys whom the priest employed in the sacrifices, then the servants who took part in it; after these the haruspices, with their knives, and the butchers, who led the victims to the altar; the different orders of priests, with their servants; first, the high priest (pontifex maximus), and the other pontifices; then the flamines, then the augurs, the quindecimviri with the Sybilline books, the vestal virgins, then the remaining inferior orders of priests, according to their rank. The images of the gods brought

up the rear; sometimes, also, a pompous show of treasures, the spoils of war. In the circus, the procession went round once in a circle, and the sacrifices were then performed. The spectators took their places, the music struck up, and the games commenced. These were, 1. Races with horses and chariots. These were so honorable, that men of the highest rank engaged in them. The whole race, in which the competitors were divided into 4 parties, consisted of 24 courses, and each course of 7 circuits, making about seven miles. Each party performed six courses, three in the forenoon and three in the afternoon. The chariots were very light, and commonly had two or four horses (abreast) attached to them. 2. The gymnastic contests. 3. The Trojan games, prize contests on horseback, which Æneas was said to have first instituted, and Julius Cæsar revived. 4. The combats with wild beasts, in which beasts fought with beasts or with men (criminals or volunteers). The expense of these games was often immense. Pompey, in his second consulship, brought forward 500 lions at one combat of wild beasts, which, with 18 elephants, were slain in five days. 5. Representations of naval engagements (naumachia), for which purpose the circus could be laid under water.

CISALPINE REPUBLIC. After the battle of Lodi (May 10, 1796), Bonaparte, on the 20th of May, proclaimed the freedom of Lombardy, and formed of it the Transpadane republic; at the same time, Bologna and Ferrara were erected into the Cispadane republic, to which Modena and Reggio were soon after added. February 19, 1797, by the peace of Tolentino, the pope ceded Bologna and Ferrara, together with Romagna, and the province of Mesola, to the French; the latter were also added to the Cispadane republic. This republic received its constitution March 17, 1797, and was united with the Transpadane, under the name of the Cisalpine republic. By this name the emperor of Germany recognised it as an independent power, at the peace of Campo-Formio (Oct. 17). It comprised Austrian Lombardy, together with the Mantuan and the Venetian provinces, Bergamo, Brescia, Crema, Verona and Rovigo, the duchy of Modena, the principality of Massa and Carrara, and the three ecclesiastical delegations-Bologna, Ferrara with Mesola, and Romagna. Oct. 22, in the same year, the Valteline or Veltlin, Worms and Cleves, belonging to the Grisons, were added; so that the new republic, which was divided into 10 depart