737 



CENTUMVIRI. 



CEREBRIN. 



733 



fugal exceeds the attractive, so that between M and p the velocity 

 towards the centre is destroyed, and from p to N velocity from the 

 centre is created. After N the attraction is again in excess, and 

 between that and A the velocity from the centre is destroyed ; after 

 which the succession recommences. 



Some readers may perhaps not find it easy to conceive how the 

 centrifugal effect should exist, when the pressure of the string, which 

 it appears to counterpoise, is not present. On which we must observe 

 that the string does not make this effort to recede, but destroys its 

 effect. If it is clear that there must be a pressure on the string in the 

 first illustration, it is because, under the circumstances, there is a force 

 to cause that pressure already existing. There are numerous experi- 

 ments in illustration of centrifugal force : take a tube, for example, 

 and place a bullet inside it ; let the tube be then put into a state of 

 rotation round one end, and the bullet will be projected straight from 

 it. The governor of a mill or steam-engine is an instance in which this 

 effort to recede is made useful. But the largest scale on which the 

 centrifugal force becomes visible is in the alteration of the time of 

 oscillation of a pendulum in going from one part of the earth to 

 another. Let A be the point of suspension of a pendulum p, and p M 



the line drawn through it perpendicularly to the earth's axis, so that 

 the angle A P M is the latitude of the place. The motion of the earth 

 carries the pendulum round in a circle of which p M is the continuation 

 of the radius, so that there should be a slight action on the pendu- 

 lum, such as should result from a pressure in the direction PM. 

 Resolve this into P Q and P z ; the second will alter the position of 

 equilibrium of the pendulum, the first will counteract a small part 

 of the weight. The second will never be made visible ; nor the first, 

 except in comparing the number of oscillations of the same pendulum 

 in different places. For the weight of the pendulum being differently 

 lescened in different places, but the mass always remaining the same, 

 the accelerating force is altered. For the law of the alteration, and 

 the history of its discovery, see PENDULUM. 



CBNTUMVIBI. [JPDEX.] 



CENTURION. A centurion in the Roman army was the com- 

 mander of a centuria, a term which we cannot conceive to have 

 originally signified anything except a hundred ; but there is no ground 

 for supposing that the word centuria contains the elements of the word 

 " viri," men. The term centuria was also applied to a hundred jugera 

 of land ; and Varro (' L. L.' v. 35) observes that the name was kept 

 after the centuria contained two hundred jugera. 



A centuria, as a division of an army, signified a number of men 

 under the command of a centurio. The form of the word cen- 

 turio is the same as that of the word curio. Niebuhr has endeavoured 

 to show that the centuria originally consisted of thirty men (' Roman 

 History,' vol. i. 471, iii. 100, Eng. Transl.) When the Roman legion 

 contained thirty manipuli and sixty centuries, the number of the cen- 

 turions would be sixty ; but as the number of the legion was not a 

 fixed number, we must suppose that the officer called a centurion had 

 nt various times a varying number of men under him. 



The passage in Livy (xlii. c. 32, &c.) seems to show that the centu- 

 rions were appointed by the military tribunes. But Polybius, in the 

 fragment of his sixth book (c. 24), states that in his time twenty men 

 were selected from the respective bodies of the hastati, principes, and 

 triarii, who composed a legion : none were selected from the velites, or 

 light troops, who were distributed among the hastati, principes, and 

 triarii in just proportion. Polybius calls the Roman centurion taxi- 

 nrchtf (Tofof>x<), which is a translation of the Latin phrase " ordinem 

 ducere." There were two centurions to each of the divisions, or 

 manipuli, as the Romans called them ; and he tliat was first chosen 

 commanded the right of the manipulus, and the other the left. Each 

 tnanipulus had its standards, which were carried by two of the bravest 

 and strongest soldiers, who were appointed by the centurions. The 

 'nturion who was first chosen was called primipilus, and was a 

 member of the general's council : he was the first centurion of the 

 first manipulus of the triarii, and he had the care of the eagle. 



The pay of the soldier in the infantry, besides food and clothing, is 

 itated by Polybius at two oboli a day, and double to the centurions. 

 The obolus is a sixth part of the Attic drachma, or one-sixth 

 part of 9}rf. This would therefore make the pay of a centurion 

 about 18. a month; by the time of Domitian it had been increased 

 tenfold. 



The ditties of the centurions were to command their several mani- 

 puli. They received their orders from the tribunes of the legion, who 

 received theirs from the commander of tho army, whom they visited 



ARTS A!D 801. DIV. VOL. II. 



every morning to receive their orders, which they then gave to the 

 centurions. They also superintended the soldiers when they were 

 engaged in the military works, such as castrametation. They had also 

 to go round to inspect the watches ; at least this is stated as among the 

 duties in some passages of the Latin writers. The badge of office was 

 a stick made of the stock of a vine (vitis). The speech of the ceu- 

 turion'Sp. Ligustinus in Livy (xlii. 34), presents a lively picture of the 

 laborious services of a Roman soldier who had worked his way up to 

 the rank of Primipilus. 



The centurions had defensive armour, a shield, an iron helmet with 

 a crest placed transversely to distinguish them from the soldiers. 

 They had also a mark (signum) on their helmet, probably to denote 

 the centuria or cohort to which they belonged. (' Vegetius,' ii. 13 ; and 

 the Notes of Stewechius.) 



The granting of temporary leave from military service to the 

 soldiers (vacatio), which is sometimes reckoned among the privileges of 

 the centurions, was only an abuse that got established at a late period. 

 It appears to be first mentioned in the beginning of the reign of 

 Tiberius (Tacitus, 'Ann.' i. 17). However, the practice had become 

 so far established that Otho thought it prudent to pay the centurions 

 out of the imperial treasury (fiscus) such amounts as they had been in 

 the habit of receiving from the soldiers on the account of the vaca- 

 tiones. Retired centurions had pensions : Suetonius mentions that 

 Caligula reduced them to 6000 sesterces, or about 451. per year. 



Under the empire it seems that the centurionships were generally 

 given as a matter of favour and patronage. 



CEPHALOTE. This name was applied to a substance found in the 

 brain of man, but which has more recently been proved to be a 

 mixture of cerebrate of lime or soda with traces of albumen and of 

 oleophosphoric acid. 



CEPHEUS, a constellation, surrounded by Cassiopeia, Ursa Minor, 

 Draco, and Cygnus, comes on the meridian at midnight in the middle 

 of August, and at eight o'clock in the middle of October. A line 

 drawn from the bright star in Cygnus to the Pole Star will be nearly 

 bisected by o and j; of this constellation. Cepheus, the King of 

 Ethiopia, was the husband of Cassiopeia and the father of Andromeda, 

 and was placed in the heavens, according to Hyginus, that no one of 

 this remarkable family might be absent. He is represented in old 

 plates as a man with a tiara on his head, kneeling on one knee, and 

 with his arms extended. 



The following are the principal stars in this constellation : 



CERAMIC ART. [PORCELAIN; POTTERY.] 



CERASIN is that part of the gum of the cherry-tree which is in- 

 soluble in cold water. It is probably some transitionary form between 

 starch and gum. 



CERATES, the name given to certain combinations of wax with 

 other substances, which are used as external applications in the treat- 

 ment of various surgical cases. They are of a degree of consistence 

 intermediate between that of plasters and that of ointments; and, 

 according to the nature of the materials united with the wax, are 

 capable of serving different ends. They may be emollient, when 

 applied to inflamed or chapped surfaces, or stimulating, when applied 

 to indolent ulcers ; and in the case of wounds or abraded skin are 

 useful in excluding the air, and preventing the dressings from 

 adhering. 



CE'RBERUS, the watch-dog of the infernal regions, the offspring of 

 Typhon and Echidna. Homer mentions him simply as the dog of 

 Hades. He is first named Cerberus by Hesiod, who speaks of him as 

 having fifty heads ; according to Horace, he had one hundred ; the 

 ordinary account gives him only three, and this number, which corre- 

 sponds to the triple form in which Geryon and Hecate appear, points 

 to the usual phenomenon in the elementary worships of ancient Greece, 

 in which a power of the nether world was also a terrestrial and celestial 

 divinity. The Chimsera was another monster of the same kind. Cer- 

 berus was also the name of a serpent which infested the neighbourhood 

 of Cape Tacnarus. The word probably signifies " dark ; " Cerberian 

 occurs as a synonym for Cimmerian in Hesychius. Nicander applies it 

 as an epithet to a toad. (Dahler, Lex. voc. peregrin. ; Steph., Then. ed. 

 Lond., i. p. xxxii.) 



CEREBRIC ACID, formerly called cerebrin, is a substance said to 

 exist in the fatty matter of the brain. It is accompanied by another 

 acid, the oleo-phoaphimv acid, which is supposed to be united to a com- 

 pound radical cerebroleine, in the manner of the fatty acids. Theso 

 substances are of a very doubtful nature, and the chemistry of the 

 nervous system is at present in a very imperfect state. 



CEREBRIN. [CEREBRIC ACID.] 



3n 



