SAW, an instrument which serves to cut into pieces several solid matters; as wood, stone, ivory, &c.
The best saws are of tempered steel ground bright and smooth; those of iron are only hammer-hardened: hence the first, besides their being stiffer, are likewise found smoother than the last. They are known to be well hammered by the stiff bending of the blade; and to be well and evenly ground, by their bending equally in a bow.
The lapidaries, too, have their saw, as well as the workmen in mosaic; but of all mechanics, none have so many saws as the joiners, the chief of which are the following. The pit-saw, which is a large two-handed saw, employed for sawing timber in pits, and chiefly used by the sawers. The whip-saw, which has likewise two handles, used in sawing such large pieces as the hand-saw will not easily reach. The hand-saw is made to be used by an individual, of which there are different kinds, as the frame-saw, which is furnished with cheeks. By the twisted cords which pass from the upper parts of these cheeks, and the tongue in the middle of them, the upper ends are drawn close together, and the lower set further asunder. The tenon-saw, which being very thin, has a back to keep it from bending. The compass-saw, which is very small, and its teeth usually not set; its use is to cut a round, or any other compass-kerf, on which account the edge is made broad, and the back thin, that it may have a compass to turn in.
At an early period, the trunks of trees were split with wedges into as many and as thin pieces as possible; and if it were necessary to have them still thinner, they were hewn on both sides to the proper size. This simple and wasteful manner of making boards has been still continued in some places to the present day. Peter the Great of Russia endeavoured to put a stop to it, by forbidding hewn deals to be transported on the river Neva. The saw, however, though so convenient and beneficial, has not been able to banish entirely the practice of splitting timber used in building, or in making furniture and utensils; for we do not speak here of firewood; and indeed it must be allowed that this method is attended with peculiar advantages which that of sawing can never possess. The wood-splitters perform their work more expeditiously than sawers, and split timber is much stronger than that which has been sawn; for the fissure follows the grain of the wood, and leaves it whole; whereas the saw, which proceeds in the line chalked out for it, divides the fibres, and by these means lessens its cohesion and solidity. Split timber, indeed, turns out often crooked and warped; but for many purposes to which it is applied this is not injurious, and these faults may sometimes be amended. As the fibres, however, retain their natural length and direction, thin boards particularly, can be bent much better. This is a great advantage in making pipe staves, or sieve frames, which require still more art, and in forming various implements of a similar kind.
Our common saw, which requires only to be guided by the hand, however simple it may be, was not known to the inhabitants of America when they were subdued by the Europeans. The inventor of this instrument has been inserted in their mythology by the Greeks, with a
place, in which, among their gods, they honoured the greatest benefactors of the earliest ages. By some he is called Talus, and by others Perdix. None except Pliny make Dædalus the inventor; but Hardouin, in the passage where this occurs, reads Talus for Dædalus. Talus is the name of the inventor according to Diodorus Siculus, Apollodorus, and others. He was the son of Dædalus's sister, and was by his mother placed under the tuition of her brother, to be instructed in his art. Having found the jaw-bone of a snake, he employed it to cut through a small piece of wood; and by these means was induced to fabricate a similar instrument of iron, that is, to make a saw. This invention, by which labour is greatly facilitated, excited the envy of his master, and prompted him to put Talus privately to death. Being asked, when burying the body, what he was depositing in the earth, he replied, a serpent. This ambiguous answer discovered the murder; and thus a snake was the cause of the invention, of the murder, and of its being brought to light. By others the inventor is called Perdix, who is supposed to have been the son of a sister of Dædalus. Perdix did not employ the jaw-bone of a snake for a saw, but the back-bone of a fish, as is mentioned by Ovid.
The saws of the Grecian carpenters had the same form, and were made with equal ingenuity as the same instruments at present. This appears from a painting preserved among the antiquities of Herculaneum. Two genii are represented at the end of a bench, consisting of a long table resting on two four-footed stools; and the piece of wood to be sawn through is secured by cramps. The saw with which the genii are at work bears a striking resemblance to our frame-saw. It consists of a square frame, having a blade in the middle, the teeth of which are perpendicular to the plane of the frame. The piece of wood to be sawn extends beyond the end of the bench, and one of the workmen appears standing, and the other sitting on the ground. The arms in which the blade is fastened, have the same form as that given to them at present. In the bench are seen holes, in which the cramps holding the timber are stuck. They are shaped like the figure 7; and the ends of them reach below the boards which form the top of it.
SAW-fish. See PRISTIS, ICHTHYOLOGY Index.