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 uuiformity 
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. 
