H 
THE TELEGRAPH. 
The second compartment of the box has a lamp with a reflector 
which sends back rays that would otherwise be lost. The 
action of the apparatus at night will easily be understood. It 
is only necessary to give a longer or shorter touch to the 
handle to send long and short flashes which will correspond 
with the dots and dashes of the Morse code. The telescope, 
l, placed outside of the box, serves to find the distant station. 
For this purpose it is only necessary to scan the horizon with 
slight vertical movements, when the ray of light which 
Fig. 3. 
indicates it will easily be found. For when this is being 
sought each station will keep the screen, d, of its apparatus 
up. The telescope must be perfectly parallel to the ray of 
light sent out by the lamp. It is therefore fixed to the box 
once for all, and, moreover, has adjusting screws, by which 
when the image of a point on the horizon has been focussed 
on the centre of a piece of ground glass at the end of the 
second chamber as in a photographic apparatus, this image 
can at the same time be caused to appear in the telescope at 
the intersection of a vertical and a horizontal wire ; then the 
parallelism is perfect. 
