VARIOUS APPLICATIONS OF TELEGRAPHY. 275 
may be produced. For example, if we indicate by dots the 
strokes on the bells, and by lines the intervals of time between 
two closely consecutive blows, thus ..-..-.. we have a 
representation of double strokes of the bell thrice repeated. A 
table of this kind showing the meaning of the different signals 
is attached to the apparatus. 
If a single stroke of the bell be heard it is an indication of 
the rupture of the wire and the suspension of the electric com¬ 
munication between the two stations. This might be occasioned 
Fig. 192. 
by a landslip or other obstacle, and of course due precautions 
would be taken accordingly. The bell-signal apparatus is very 
simple, and it requires no other attention than the winding up 
of the weight from time to time. Special instructions are, 
moreover, given by those in charge of the telegraphs to all per¬ 
sons concerned in understanding the details of the bell 
apparatus, so that they may take the requisite steps to ensure 
its regular action. 
Applications of telegraphy to giving alarm of fire .—As far 
back as 1851 the town of Stuttgard was provided with a 
complete network of telegraphs connecting the stations of the 
fire brigades, and acting as a constant check upon the daily 
and nightly effectiveness of its watchmen. A recent work by 
M. Yon Fischer Truenfeld tells us that Germany is almost the 
only country in Europe where this important service has been 
established with completeness. We learn also that in America 
most of the great centres have systems of telegraphs appro¬ 
priated to giving alarm of fires. 
Thanks to the use of this plan the proportion of serious fires 
at Berlin scarcely reaches 3 per cent., and at Hamburg it is 
