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

584 PARATONNERRE, OR LIGHTNING ARRESTER.
-closer, in fact, than any other wire or piece of metal inside the instrument or the office. The wire e is further furnished with two nuts, f, fitted with points, made by gauge to
approach almost within hairsbreadth of the cylinder. The
boxwood terminations a and d are also capped with brass disks;
from the upper disk, points approach the earth-cylinder; and
from the lower end of the earth-cylinder, points are presented
to the disk. The object of the coil g, of very fine wire, is,
that, from its tenuity and from its juxtaposition to the earthcylinder, it shall have a better chance of being burned, in an
extreme' case, than either the wire of the bell coil or that of
the needle coil. The use of the points does not require any
explanation.
The first set of these conductors were placed at Tunbridge
Wells station; and not many weeks had elapsed before a lightning flash entered the station, and it behaved with the apparatus as I had been led to expect. It passed safely through
the stout wire E, and immediately on arriving at the fine wire
g^, it darted off to the cylinder, and, by its explosion, singed
the silk and exposed the wire where I have placed a black
spot, near A. In this case the flash was moderate, and the
wire was not burned.
It went a step further, and another of its features was called
into requisition, on 8th August, 1849. During the night a
violent thunder-storm occurred, the effects of which were especially manifested on the Ashford end of the Ramsgate branch.
Three poles, unprotected by lightning-wires, were splintered at
Chartham, about two miles beyond Chilham; and the lightning entered both Chilham and Ashford stations, and, by its
snappings and explosions, very much alarmed all on duty.
When all was over, it was found that at Chilham, where there
were no lightning conductors, the wire of the bell-coil was
burnt, and of both the electrometer coils, and other severe
explosions occurred about the apparatus: one of the No. 16
size copper wires was burnt and broken. At Ashford there
were lightning-conductors on the two instrument wires, but
not on the bell-wire (a few days previously the bell-coil had
been saved by the lightning-conductor being burned; the latter
was brought away to be examined, and had not been replaced).
It was now found that the Ashford electrometer coils, both of
which had conductors, were saved; the fine wire, g, of the
lightning conductor being burnt by the explosion in both cases,
but the bell-coil, which was unprotected, was visited by the
discharge and burned.
Lightning flashes occasionally disturb the polarity of the