284 EDWARD H. SANBORN 



The automatic and semi-automatic principles have been 

 extended to new and larger classes of work than before. 



The forming tool has become a recognized shop ap- 

 pliance. 



The oil tube drill has been developed from an excep- 

 tional to a regularly used tool. 



Compressed air portable tools have been developed sub- 

 stantially de novo. 



The application of the power press has been greatly 

 extended. 



Electrical driving has come into general use. 



The system of heavy portable machine tools in conjunc- 

 tion with a massive iron floor plate has been originated. 



The grinding machine has been largely increased in size, 

 power, and extent of use. 



Closely related to machine shop practice, though scarcely 

 coming within machine tool classification, may be mentioned : 



The development of traveling cranes. 



The origin of high speed steels for cutting tools. 



These lines of development may be discussed briefly in 

 the above order. 



The extension of the semi-automatic principle, as illus- 

 trated by the hand operated turret lathe, has been chiefly 

 toward the execution of larger and heavier work, while the 

 use of the entirely automatic turret lathe has been not only 

 in the same direction, but has been adapted to entirely new 

 classes of work. An illustration of the first line of develop- 

 ment is found in several types of turret lathes which, although 

 employing certain methods of attacking the work which were 

 not known before their advent, is nevertheless essentially an 

 extension of the turret principle to larger work than had 

 before been done by it. 



An illustration of the second line of development is to 

 be found in the magazine feed full automatic turret lathe. 

 Prior to the advent of this machine, the full automatic machine 

 had been employed exclusively for making screws, studs, 

 etc., from bar stock which was fed to the machine through 

 the hollow live spindle, the pieces being first turned, threaded, 

 etc., and then cut off, when the bar of stock was fed down- 



