48 MODERN BLACKSMITHING 



cold and let it cool slowly, this will make the drill both 

 hard and tough. By this simple process I have been 

 able to dress drills and get such a good temper than 

 only two per cent would break. Another way to 

 harden is to heat to a very low heat and cool it off 

 entirely at once. A third way is to temper as hrst 

 stated and when yellow set the drill in water only one 

 half an inch deep and let it cool. By this process a 

 good per cent will break just at the water line. 



