126 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1907. 
to the right the corresponding sign. The choice of the disk is made 
according to the combination of the perforations on the ribbon, in a 
manner analogous to that of the combiner and feelers of the Baudot 
telegraph. The spaces are cast in the same way as the letters, the 
mold being closed by a disk without a matrix. The thickness of the 
space is determined by the slide valve of the mold, the heel of which 
strikes against the justification apparatus. This mechanism con- 
sists of four disks mounted on the same axle, forming a combination 
which expands or contracts according to the result of the calculation 
of justification. When a line is finished, it is pushed automatically 
into a galley. The machine then stops casting for three turns, while 
the justification apparatus receives the measurement corresponding 
to the spaces to be furnished to the line which is to be composed, a 
dimension indicated by the perforations D,, D, (fig. 10). These 
perforations are reserved for justification at the end of each line. 
The first row, D, (fig. 10), indicates by the position of its perforation 
the number of spaces at the begin- 
ning of the line which should re- 
ceive the supplementary correction 
of one-tenth of a millimeter; the 
second row, D,, indicates, by add- 
ing the values determined by the 
position of its perforations from 1 
to 5 (perforation 5 representing 
the value of 10), the number of 
tenths of a millimeter to be added 
Fic. 13.—Diagram of registering ap- OY Subtracted to all the spaces of the 
paratus in the casting machine of the line 
electrotypograph. 
Let us take for example the band 
shown in fig. 10. The perforations of series 6 represent subtraction, 
those of 7 addition. 
In D, we find perforations 3 and 6 indicating that it is necessary 
to subtract (perforation 6) one-tenth of a millimeter from each of 
the first three (perforation 3) spaces of the line. 
In D, we find perforations 1, 2, 5, and 7, showing that it is neces- 
sary to add (perforation 7) to each normal space of 15 tenths of a 
millimeter, a number of tenths of a millimeter 1+2+10 (perfora- 
tion 5 having the value of 10), that 1s 13 tenths of a millimeter. 
Thus in this line, the first three spaces will be cast with a thickness of 
15+13—1, or 27 tenths of a millimeter, and all others with a thick- 
ness of 15+13, or 28 tenths of a millimeter. 
The perforated strip, A (fig. 13), is carried along by a cogwheel 
whose teeth engage the perforations of the series 0. 
The machine makes 90 turns a minute, advancing the band one 
division and casting a character at each turn. The movement of 
