Various plans or processes have been and are employed for tempering or hardening different kinds of steel. The art of tempering has always—and justly so—been considered ol ,, a very delicate-nature. This is the reason yL why there are such a variety of modes in prac tice, and such an incongruity existing among them all. Saws are the most important of all cutting tools. More work is done with them than with any kind of tool. They saw up the forest into boards, planks, joists, and beams for houses, or into ribs and planking for ships. Day and night the sound of the saw, plying at its busy toil, never ceases throughout our land. It is heard far up in our country, making music with the wild waters of St. Anthony's Falls, and its rough bass voice mingles with the sounds of busy life in our city of myriad homes. Blessings on the man who invented the saw. Who was he 1 It is an old tool, and probably Tubal Cain was its author, but the Greeks have instituted the claim for Talus, the son of Dasdalus' sister, and he has a place in their mythology—a place among their gods. This shows how the Greeks honored early inventors. It is said that he was employed to cut through a small piece of wood, and having found the jaw bone of a snake, he employed it, and afterwards made a steel instrument—the saw—from that natural model, for which his master put him to death for spoiling his business, and thus the serpent was the means of doing great good and evil; the world was benefitted by the inventor, and, as if he was the prototype of his race, he benefitted others but was sacrificed himself to the spirit of intolerant self-interest. A painting still preserved among the antiquities of Herculaneum represents two genii at the end of a bench on which is a piece ol wood to be sawn, which is secured by clamps. The saw which the genii are about to use has a perfect resemblance to our frame saw.— This shows that the ancient Greeks and Romans were well acquainted with the saw, but none of the aborigines of America knew anything about it, when this continent was discovered, and it does not appear that either the Greeks or Romans knew anything about saw mills, that is, driving saws by water power. This invention is claimed by the Germans for a burgher named Gis Saegemuller, who erected one in 1338. In 1663, a Dutchman erected the first saw mill in England near London but its introduction was so violently opposed by the sawyers, that he had to abandon his business. It was more than a century after that before another mill was erected. In 1768 a rich timber merchant erected a saw to be driven by a windmill, near Limehouse, below London. This mill was torn down by a mob, but the government made good the loss to the proprietor, and punished several of the rioters. Soon after that a new mill was erected, and the saw in it was suffered to buzz on unmolested. We do not know when saw mills were introduced into our own country, nor whethei jt was by the English or Dutch settlers, bu) we presume the Dutch were the first, as saw mills were long in use in Holland before they were in England. A great number of patents have been granted for improvements in saw mills and sawing. We coma very near the mark when we state that 300 patents have been granted for improvements in saw mills and sawing, and fifty for improvements on saws, such as for gumming, sharpening, and setting them. As we stated last week," the expense of saw sharpening, setting, c, is the greatest about a saw mill," therefore every improvement in saws whereby they can be made cheaper, rendered more durable, c, is of immense importance to our country. The tempering of saws, especially long reciprocating, and large circular saws, has always been a very difficult, intricate, and troublesome process. It has been the custom (and it is universal we believe,) to heat saw blades in a bath of hot oil, or molten lead, and then cool them, to make them hard, in cold water or a salt brine. On the 27th of May last year, Mr. Henry Waterman, of Williamsburgh, N. Y., obtained a patent for an improved mode ol tempering saws of all descriptions, -viich has reduced the process to simplicity itself, and the saws which are hardened by it, we have been assured, endure much longer, requiring to be sharpened much seldomer than other saws. The saws are straightened and hardened at Mr. Waterman's factory as follows:—For circular saws there is a heavy solid round anvil, over four feet in diameter, set on the floor. In its centre is a spindle, which passes through the opening in the mid- dle of the saw, and acts as a guide. Above this is a movable circular metal drop, weighing 4 tons 7 cwt. It has a smooth face and is suffered to fall suddenly for about two feet down upon the saw, which is placed upon the anvil. The saw is heated to a low, dull, red color, in an oven, and is placed with tongs upon fingers of angle irons, above the anvil, which fingers retain it there until the hook which holds up the drop is drawn out, when down comes the heavy drop like a mighty avalanche upon the saw, the supporting fingers fly out, and the saw is squeezed between the drop and anvil with a pressure which refines the steel by forcing its expanded molecules closer together, and thus the saw is tempered in a most sicnple and efficient manner, and done with great rapidity. The drop is allowed to rest upon the saw until it is partially cooled; after this the drop is lifted by a pinion and wheel which works a block and tackle that suspends the lilting hook. The saw is then taken out and requires no more labor to harden it. Some of the saws, although submitted to such a blow and pressure, are still somewhat warped when taken out, but the hammer does all that is required to be done alterwards. Straight saws are treated in the same manner, only a different shaped anvil and drop are employed. This process of tempering is certainly a beautiful and simple one, and no better evidence of its utility can be adduced than to say, that the large saws thus treated are fast superseding others in our saw mills.