The telegraph manual: a complete history and description of the semaphoric, electric and magnetic telegraphs of Europe, Asia, Africa, and America, ancient and modern.

578 PARATONNERRE, OR LIGHTNING ARRESTER.
nected with the earth by means of the large copper rod or
wire E. The pointed cones u q connect respectively with the
line wires L. and L.. and with the wires 1' 1", which lead to
the apparatus. The voltaic current from the distant station
enters, for example, through the wire L. of cone u, thence by
the wire 1' to the apparatus, and thence through l' to the cone
q and line wire L.. On the other hand, the current may
come from line L.. and traverse the metallic circuit composed
of q 1", the apparatus 1 u and L. The voltaic electricity follows the metallic circuit, but the lightning seeks its course to
the earth through the diamond-shaped copper o k. This combination, in principle is the same as fig. 6, employed on the
American lines. I am unable to say which of the two are the
best for the purposes. On the American lines, the flat plates
are found to be perfect in the protection of the telegraph apparatuses. Mr. Nottebohn informed me that the above device
answered fully the objects in view, and that he had never
known of its failing to successfully preserve the instruments
of a station. The flash from cone to cone was observed on
many occasions when, at the locality, there was not a cloud to
be seen.
BREGUET'S PARATONNERRE.
On the French telegraph lines a different mechanism is used
for the preservation of the apparatuses of the stations. At an
early day in the history of French telegraphy, the distinFig. 14.
guished Breguet invented an arrangement represented by fig.
14. This paratonnerre is composed of copper or brass plates,
L E and L/, with edges like saw teeth, as seen in the figure.
The line wires are fastened at L i'. Between the plates L L is