876 TRAysACTioys of the American Institute. 



Pieces of irregular form are difficult to temper without war]-)ing 

 or cracking; as a rule, insert the thickest part in the water tirst, or 

 insert the piece into the water in such a manner as to have it cooled 

 in all its parts at the same instant. A wag who was the foreman in 

 a'smith shop connected with an establishment in which I was once 

 employed, used to say to his workmen : " The whole art of temper- 

 ing, so far as it relates to warping the work, consists in putting your 

 piece into the water straight, and taking it out straight !" It is 

 highly important to be able to take it out straight, certainly. Steel 

 should always be heated in a charcoal fire, for any other fuel is likely 

 to contain sulphur, which, if communicated to the steel, injures it ; 

 or phosphorus, which is quite as bad. Large masses of steel should 

 be heated with extreme slowness ; a large ingot may be cracked in 

 the center by heating it too rapidly on the outside. Ingots from 

 which steel rails are rolled are ruptured in the center by too sudden 

 cooling" in the mold, and the defect is perpetuated in the rail. The 

 ingot may be broken by being heated or cooled too rapidly. If the 

 ingot could be cast in a sand mold, instead of an iron one, which 

 withdraws the heat from the surface rapidly, and passed through the 

 rolls before its temperature was reduced, the rail would probably be 

 sound, and a serious accident to a train might thus be avoided, I 

 have no doubt this is the most prolific cause of the accidents which 

 result from broken rails of steel ; and the uncertainty which attends 

 fabrications of this kind gives all persons a distrust of a material, 

 which, if properly manipulated, could be relied upon with confidence 

 for the performance of the amount of work expected of it. 



Heavy forgings of steel should not be kept under tlie hammer 

 long at a time , it is better to return it frequently to the fire that 

 there may be no great variation of the heat from the beginning to 

 the end of the work ; and when the job is finished cover it up in a 

 bath of slacked lime, which is a good non-conductor, and the slower 

 it cools the better. Thus you may avoid tensions which if not the 

 direct cause of the breaking of the work will materially assist other 

 forces to do it. Xo strength whatever can possibly be given to fabri- 

 cations of iron or steel which the immense force arising from 

 unequal expansion may not be sufficient to overcome. 



After Mr. Wiard had concluded, Mr. Babcock said that nail 

 machines are made of chilled cast-iron, which seems not to be 

 affected by the hot metal plates from which the nails are cut. 



Mr. Wiard stated that this was done on account of the difficulty of 



