286 EDWARD H. SANBORN 



in machines of the lathe class, in which the work revolves 

 against a fixed drill, although the arrangement is also used 

 in upright drilling machines, in which the tool revolves. 

 The history of this appliance is almost exactly parallel to 

 that of the forming tool. It was known and used to a 

 limited extent before 1890, having been first used for the 

 drilling of gun barrels; but its more extensive application 

 must, like that of the forming tool, be credited to the bicj^cle 

 industry, the development of the two tools being, in fact, 

 simultaneous. The forming tool having been successfully 

 applied to the machining of the outside of bicycle wheel 

 hubs, it was found that a portion of the gain due to its faster 

 action was lost because the simultaneous drilling of the hole 

 required more time than the work upon the outside of the 

 piece. This condition of things led to the adoption of the 

 oil tube drill for this work, and from this application the use 

 of the appliances has become widely extended. Of the two, 

 the oil tube drill is no doubt the more important. The in- 

 creasing use of hollow spindle lathes and automatic and hand 

 operated turret lathes, in which the spindles are necessarily 

 hollow, not to mention milling and other machines having 

 hollow spindles, has given a wide field of usefulness to this tool. 

 The numerous class of small and unpretentious pneumatic 

 tools which have very recently come into prominence and 

 extended use may, it is quite possible, be looked upon as the 

 most important single machine tool development of recent 

 years. Of these, the first in order of importance as well as 

 of time is the pneumatic hammer. Originally devised as 

 a substitute for the hand hammer and chisel in the machine 

 shop and in stonecutting, it has extended its field of useful- 

 ness to many other fields, and is to-day an indispensable 

 tool in shipbuilding and in the erection of steel frame buildings. 

 Of the general class of compressed air tools, the next in im- 

 portance to the hammer is perhaps the rotary drill, which, 

 in its numerous forms and applications, has introduced me- 

 chanical power in place of hand labor for classes of work to 

 which the application of mechanical power seemed almost 

 hopeless. These and numerous other applications of com- 

 pressed air to machine and similar work stand almost wholly 



