374 Recent Advances in Telegraphy . [July, 
successfully from Fredericia, in Jutland, to Copenhagen, a 
distance of 390 kilometres. 
Mr. Elisha Gray’s first English patent bears date of 1874, 
a few months before M. la Cour’s ; but in it there is no 
mention of multiplex telegraphy. Subsequent patents, in 
1875 and 1876, describe the development of his system and 
its application to multiplex signalling. His principal me- 
thods of sending are represented in Figs. 13 and 14. In 
Fig. 13 the vibrator is a tuning-fork or reed, R, placed 
between two eledtro-magnets, A and B, which can be ad- 
justed by the screws d and g to or from the reed, so as to 
have greater or less power over it. The reed is barbed with 
two short springs, which play against the adjustible contadt- 
points a and h, making contadt with them alternately as the 
reed vibrates. The reed is perpetually maintained in vi- 
bration by means of a local battery and the eledtro-magnets 
in the following way ' The local battery is connedted up, 
as shown, through the eledtro-magnets and the fixed end 
of the reed. When the reed vibrates so as to make contadt, 
by means of its spring, with b, and break contadt with a, 
the eledtro-magnet A is in circuit and adtuated by the cur- 
rent, while the magnet b is cut out of circuit by the short- 
circuit wire w. The magnet A therefore exercises a pull 
upon the reed R, which assists the reed in vibrating towards 
