124 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1907. 
The difference between the length of the line as it must be justified 
and its length as actually made is the difference between / and i; 1 
may be either greater or less than A. 
Let us say that the difference between / and A, divided by 1, is +g, 
and suppose first that this division gives a quotient g without re- 
mainder. Each space in the line would be increased (++) or dimin- 
ished (—) by the amount g according to its sign. These calculations 
are performed automatically by the machine, and it is the value of ¢ 
aan 
{ : 
aa 
Fic. 11.—The casting machine of the electrotypograph. 
that is indicated by perforations on the ribbon when the justification 
lever is operated. . 
Let us suppose, however, that the difference between / and 4, di- 
vided by , gives the remainder v, which is generally the case, as the 
machine can not calculate the spaces closer than a tenth of a milli- 
meter. In this case besides the correction g, which affects each space 
in the line, the » first spaces receive a supplementary correction of 
one-tenth of a millimeter, until the remainder v is used up. 
Proof before casting—The proof copy, furnished by the writing 
machine working in the ordinary way, may be corrected even before 
the type is cast. Corrections which require the resetting of one or 
