Page:The American Cyclopædia (1879) Volume XIV.djvu/675

 SAW 651 vicissitudes he recovered not only all its pos- sessions, but acquired in 1713 a part of the duchy of Milan and the kingdom of Sicily, which he exchanged in 1720 for the island of Sardinia, with the title of king. (See VIC- TOR AMADEUS, and SARDINIAN STATES.) Thus, after having been counts and dukes of Savoy for 700 years in the aggregate, these princes were ranked among royal dynasties, allied with almost all the great houses of Europe, and finally the reigning king Victor Emanuel has become the ruler of all Italy. (See ITALY.) Except during the French domination under the republic and Napoleon I., Savoy remained a part of the Sardinian states till 1860, when by the treaty of Turin (March 24) it was ceded to France, together with most of the county of Nice, on condition that the inhabitants should approve of the transfer; and a large majority of affirmative votes having been cast at the election for that purpose, the county was formally annexed to France, June 12. SAW, an instrument usually made of a steel plate with teeth along one edge, used for cut- ting wood, ivory, stone, and the softer metals. The ancient Egyptians used saws of bronze, and applied them to cutting out planks from logs. The saw was single-handed, and the log was placed on end and secured to posts set in the ground. The inventor of the saw was deified by the Greeks, and called by some Talus and by others Perdix. The saws of the Grecian carpenters were like the straight frame saws of modern times, the blade set across the middle of the frame, with the teeth perpendicular to its plane. The block of wood to be sawn was clamped down upon a bench, and the workmen stood on opposite sides of this, one at each end of the saw. Sa^s are of various forms and sizes, according to their intended use. The older forms are straight strips of steel, either set in a frame, or simply provided with handles at each end, so as to be moved forward and back by two persons ; or the plate is made stiff enough for a single handle to answer, when it is worked by one person holding it in one hand. In modern times saw blades are often circular, the teeth cutting as the saw revolves constantly in the same direction. Steel plates intended for large saws are prepared from ingots carefully made to secure uniform quality, and after being rolled they are slit into the shapes for the different saws. The edge intended for the teeth is then ground true, and the teeth are cut by a punch at a fly press. The rough edges left by the punch are filed down and the teeth are sharpened. The blades are next heated in ovens to a red heat, and then im- mersed horizontally and edgewise into a trough containing oil with certain portions of melt- ed tallow, beeswax, rosin, pitch, &c. To re- move the excess of hardness they thus acquire, after wiping off a portion of the composition that adheres to them, the blades are held over a fire until that which remains ignites; this is called " blazing off." The more that is re- moved of the composition before this burning, the. harder is -the blade ; and thus its temper is regulated for the kind of saw required. To give it uniform density throughout, the blade is next hammered over its face upon an anvil or polished steel ; this is called "planishing" or " smithing." The next process is grinding the surface, to reduce the thickness of the metal from the teeth toward the back edge. Small blades are held against the stone by means of a board laid upon them, and large saws are suspended at each end. The finishing processes are repetitions of the planishing and grinding, together with polishing by smooth stones and with emery. The teeth are vari- ously shaped for different saws. The most simple are made by angular notches, the angle at the apex of the notch being of 60. This is most convenient for sharpening, as the com- mon triangular or " three-square " file is just adapted to its figure. "When the teeth are made with equal sides, they are said to have an upright pitch ; and when they make a zigzag of alternating long and short lines, they are said to be flat or to have considerable pitch. The former are adapted for cross-cut saws, worked by two men, one at each end. Such teeth lack the chisel-like effect of those of a low pitch, and rather scrape away the wood than tear into it like the latter, which cut only when the saw is moved in the direction toward which the teeth point. Hand saws in the United States and England have the teeth pointed from the handle ; in Asiatic countries and in Greece they have always been made with teeth point- ed the other way. A straight cut upon a line can probably be made better by the thrusting cut, and in this the sawdust is thrown out more freely ; but the force is certainly applied to better advantage as regards the saw in pulling it in the line of its greatest strength than in pushing; and for very slender saws, in which it is an object to dispense with all unnecessary width and thickness, as in the keyhole and other similar sorts, it would ap- pear decidedly better to adopt the East Indian practice. Some large saws are notched at a sharper angle than 60, and for these special files made for the angle are used, and are known as mill-saw files. Teeth made at a low pitch in large saws would become clogged with sawdust unless the space between them were enlarged, and the various forms in which this is done give distinctive names to the teeth. In large mill saws and circular saws the space between the teeth, which may be 2 or 3 in., is hollowed out in a curve, and the outline is much like a fish hook in form, the shank of the hook bending back to make the back of one tooth, and the point curving round to form the under side or face of the next. All saws used for cutting wood require some provision against their liability to become jammed and the teeth clogged in the narrow passage they make for themselves. This is sometimes ef-