MECHANICAL COMPOSITION IN PRINTING—TURPAIN. 121 
speed of composition. As usual, these machines, certain types of 
which have attained the highest degree of perfection, apply the prin- 
ciple of the division of labor. Two absolutely distinct machines are 
associated: First, a composing machine with a keyboard; that is, a 
writing machine which perforates a ribbon to be transferred to the 
casting machine; second, a casting machine, which receives the per- 
forated ribbon from the composing machine, casts the successive let- 
ters as well as the spaces, and assembles them in justified lines. 
The principle of these machines was conceived in 1872 by an 
American named Westcott. One can not help comparing the prin- 
ciple followed in both of these machines, namely, the perforated 
ribbon, with that of the Wheatstone automatic telegraph, invented 
by the physicist Wheatstone in 1859. 
The first two types in this class are the Goodson graphotype and 
the Lanston monotype (pl. 11). 
The graphotype, to solve the problem which we have just men- 
tioned, employs more than 650 contacts of mercury and 60 electro- 
magnets. There are, therefore, opportunities for inaccuracies in its 
operation. Furthermore, the keyboard operator must, at the end of 
each line, read two numbers on the tables or dials, and then choose in 
a definite order a certain number of special keys which control the 
justification perforations. Each movement of the block which car- 
ries the matrices is followed by a sudden stop, and as the block weighs 
3 kilograms and performs 20,000 movements per hour, this is a source 
of wear and tear on the machine. 
The monotype is based on the same principle. The manipulation 
of the keyboard of the perforating machine produces a ribbon, per- 
forated with letters clear like those of a typewriter, thus allowing an 
inspection of the composition. Justification, as in the graphotype, 
necessitates a reading and the choice of a lever; the speed of compo- 
sition can not, therefore, attain that of the ordinary typewriter. 
The perforated ribbon is then transferred to the casting machine, 
where it is drawn between a series of holes which follow the line of 
_ perforations and a groove through which comes a jet of compressed 
air. This jet of air passes through the perforations and actuates a 
mechanism which frees the matrix corresponding to the perforated 
character and carries it under the melting pot containing type metal 
kept in fusion by a gas jet. A drop of molten metal runs into the 
matrix and thus forms the type which, cooling almost immediately, is 
deposited in a channel where the entire line of type is assembled. 
Corrections are easily made, as each type is a separate piece. Never- 
theless, the whole process is a delicate one on account of the appli- 
cation of compressed air, 
