The usual method of tempering saws is to heat, and then dip them in oil. This process is slow, costly, and laborious. It is also disadvantageous, because the Bawl become warped, and require to he hammered up straight again by hand. A late improvement consists in tempering and straightening the saws at one operation. This is done by heating the saws to the proper degree, and then pressing them with a sudden and powerful stroke between two surfaces of cold iron. A drop press is employed for the purpose. The mechanism is quite simple and inexpensive. Its use effects an important economy in the manufacture of nearly all kinds of saws, and aiso improves their quality.