38 
THE TELEGRAPH. 
shown in the figure, for that arrangement is found to be too 
sensitive to slight shocks. The hook c, instead of having the 
arrangement shown in the figure referred to above, and shown 
also on the left-hand side of Fig. 10, has in reality the arrange¬ 
ment represented by the right-hand diagram of that figure. It 
is released w T hen the vibrations of the strip u have in a manner 
driven it clear, n is here inclined, and there are other modifi¬ 
cations ; as for instance, the magnet has only one bobbin, the 
other end instead of a bobbin carrying the strip n itself, so 
that the vibrations of the latter are amplified. As thus 
Fig. 11. 
arranged the apparatus works very well. It is somewhat deli¬ 
cate, perhaps, but it would no doubt be impossible to adopt 
anything firmer, on account of the small amplitude of the 
movements which have to be employed. An electric bell can 
be added to the apparatus when required, so that, if the clerk 
has to leave his office, he puts his signals into a local circuit 
with the bell. As soon as any one of the discs falls the bell is 
set going, and the operator is made aware of the call, and comes 
to see who requires to communicate. In practice these signals 
are arranged by sixes in one box, which has the general form 
represented in Fig. 11. 
Thus, thanks to M. Ader’s elegant apparatus, subscriber No. 5 
will not have to wait indefinitely with his telephone at his 
ear. A clerk will hasten to answer him. But it is not with the 
clerk that No. 5 wishes to converse, but with another sub¬ 
scriber who is known to him, and whose number is 9, say. This 
correspondent must be advised and placed in communication 
with No. 5. This operation so easily stated is not so easy to 
accomplish, and the difficulties attending it are greater in 
proportion as the subscribers are more numerous. 
The following is the manner of overcoming those difficulties 
