109 
Revolving Telegraph . 
blank* to receive the shutters covering the windows* 
which fall back by their own weight. The ropes 
which hoist them are seen passing over pullies* and 
down into the observatory* through the perforated beam 
and shoulder. 
N* a flag* surmounting the whole* to be occasionally 
used for signals. 
O* the observatory. 
P* the signal officer. 
Q* the workman employed in pulling the ropes to consti- 
tute the signals* as ordered by the officer at the tele- 
scope. 
The ropes are divided into 13 spaces* corresponding 
with the 13 chambers of the telegraph; by pulling either 
of which to a fixed point* such or such a window is ob- 
scured. 
Fig. 2. a* the lower beam of the frame* with the shaft &* 
passing through it* and having the shoulder c* connect- 
ed : The openings for the ropes are here seen in them, 
the iron cap ; e e* the arms supporting the axes : /* the 
solid axis passing through the hollow axis g ; h * the 
upright* and returning parallel arm of the solid axis* 
playing on the periphery of the hollow axis with a fric- 
tion roller i . 
&* the arm of one of the shutters attached to the returning 
arm. 
I * the inner wheel* (with a shutter morticed into its inte- 
rior surface*) attached to the rim of the hollow axis. 
m * the outer wheel* fixed to the solid axis* by which the 
shutter Je is worked. 
Fig. 3* an enlarged view of one of the castors on which 
the telegraph rotates. 
Fig. 4* section of the shaft and shoulder* showing the 
manner of constructing the holes for the passage of the 
ropes* by which they work freely* without being im- 
peded by the rotation of the machine. 
