Mechanics, denotes a wheel or circle, concentric with the base of a cylinder, and moveable together with it round its axis.

Perjury is defined by Sir Edward Coke to be a crime committed when a lawful oath is administered, in some judicial proceeding, to a person who swears wilfully, absolutely, and falsely, in a matter which is material to the issue or point in question. In ancient times it was in some places punished with death; at other periods it made the false swearer liable to the punishment due to the crime which he had charged the innocent person withal; and at others, again, it subjected him to a pecuniary fine. But though it escaped human, yet it was thought, amongst the ancients in general, that the divine vengeance would most certainly overtake it; and there are upon record many severe inflictions from the hand of God, as monuments of the abhorrence in which this atrocious crime is held by the Deity. The souls of the deceased were supposed to be employed in punishing perjured persons. Even the inanimate creation was thought to take vengeance on this crime. The Greeks supposed that no person could swear falsely by Styx without some remarkable punishment; and that any one guilty of perjury could not enter the cave of Palamon at Corinth without being made a memorable example of divine justice. In Sicily, at the temple of the Palici, there were fountains called Delli, from which issued boiling water, with flames and balls of fire; and we are told that if any person swore falsely near them, he was instantly struck dumb, blind, lame, or dead, or was swallowed up by the waters. But although perjury was thus held in general abhorrence, yet in spite of the credit given to such accounts of divine inflictions, it was so much practised by the Greeks, that Graeca fides became a proverb. Lovers' perjuries, however, were supposed to pass unnoticed, or to be but very slightly punished with blackness of the nails, a decayed tooth, or some similar diminution of beauty. The ancient philosophers were so afraid of perjury, that even an oath before a judge was never admitted excepting for want of other proof. Plato's precept was, not to administer an oath wantonly, but upon deep grounds, and with the strictest caution. Ulpian gives his opinion thus: "Some are forward to take oaths from a contempt of religion; others, from an extraordinary awe of the Divine Majesty, carry their fear to an unreasonable superstition, so as to make an equitable decision of a judge necessary." "No man will perjure himself," says Aristotle, "who apprehends vengeance from Heaven and disgrace amongst men." Clinius was so very scrupulous, that rather than take even a lawful oath, he suffered the loss of three talents. Perjury, in the time of Philo Judaeus, was abominated and capitally punished amongst the Jews; but since that time they have much degenerated, being poisoned by the Talmud, which states, that he who breaks his promissory oath, or any vows he enters into during the year, if he have a mind that they should be ineffectual and invalid, may rise the last day of the year, and say, Whatever promises, oaths, and vows, I may think fit to make in the year following, let them be null, void, and of no effect. The modern Jews employ the same artifice, thinking that they may thus lawfully deceive the Christians.