TELEGRAPHIC APPARATUS . 
229 
the current will traverse the electro-magnet, the armature will 
be attracted and the motion of the lever bringing the inked 
wheel into contact with the paper that is passing under c, a 
black mark will be made of a length depending jointly upon 
the rate at which the paper passes and the interval of time 
during which the key m is depressed. When the key is released 
the current ceases to pass, the electro-magnet no longer attracts 
the armature, the spring draws A upwards, and the wheel b 
leaves the paper and again dips into the ink. An instantaneous 
depression of M will cause the paper to be marked simply by a 
dot, while a longer depression will produce a line or dash, and 
Fig. 162. 
this gives the means of producing the signals of the Morse 
alphabet. 
Fig. 163 shows a complete Morse instrument, as con¬ 
structed by Siemens of London. Digney’s Morse apparatus, 
shown in fig. 164, was among the first in which the inking 
arrangement was introduced into the telegraphic service. In 
this, the inking wheel rotates in a fixed position, and receives 
its ink from a roll covered with cloth constantly charged with 
printer’s ink. The style of the movable lever connected with 
the armature brings the paper into contact with the inking 
wheel, while the current passes ; and the dot and dash signals 
are made as already explained. 
Siemens’ apparatus have been most used in England; and 
Digney’s in France and elsewhere. Some of the latter have 
been in use in the India Office since 1862. In fig. 164, it 
will be seen that the roll of paper is contained in a drawer where 
