TRUE SURFACES AND ACCURATE MEASUREMENTS ROBB. 25 



guaranteed to be accurate within 1/10000 of an inch, and when 

 such gauges are applied to a piece of machinery there is no 

 difficulty in producing work rapidly and uniformly correct 

 within 1/4000 or 1/5000 of an inch. 



In addition to the evident advantage this system has over 

 the old " Cut and Try System," by which each part of a machine 

 was fitted especially to the other part, it eliminates the indivi- 

 dual factor to a considerable extent, so that perfection of product 

 is not so much dependent upon the individual whose skill has 

 been acquired by long years of experience, and who must have 

 produced much inferior work before he attained his present 

 deftness. The manufacturer is enabled to furnish plans of each 

 machine giving the exact sizes, marked in thousandths of an inch, 

 and each mechanic is able, by the aid of his gauges, to produce 

 any number of parts which are exactly alike, and will fit any 

 other part of similar machines. By preserving this uniformity 

 in all the machines he produces, the manufacturer is able to 

 determine accurately from the machines in use where imperfec- 

 tions exist, and can record and store up his accumulated experi- 

 ence and make corrections and improvements as required. 



