PH LINE.

The 1st Division of the Royal Engineers, Telegraph Battalion, now
encamped at Chevening, close to Lord Stanhope's park, as a summer
exercise is engaged in running a military telegraph field line from
Aldershot to Chatham. Along the whole of the line the wire is
supported on light fir and bamboo poles. The work has been carried out
with unusual celerity. From Aldershot to Chevening, a distance of
fifty miles, the line was erected in a day and a quarter, or under
thirty hours, the detachments employed having worked or marched all
night. This is, it is said, the greatest length of telegraph line ever
laid within so short a time. The result cannot fail to be useful, for
by the new line communication is now established both by telegraph and
telephone between Aldershot and Chatham. For laying such telegraph
lines to accompany calvary, a light cable is made use of. This is
carried on reels on a wheeled cart, and can be laid at the rate of six
to seven miles an hour. The Telegraph Battalion of the Royal Engineers
comprises two divisions. One is employed in time of peace under the
Post Office in the construction and maintenance of postal lines; the
other, stationed at Aldershot, is equipped with field telegraph
material.--_Daily Graphic._

[Illustration: LAYING A MILITARY FIELD TELEGRAPH LINE.]

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AN ELECTROSTATIC SAFETY DEVICE.

This device, as shown in the accompanying illustration, is a glass
cylinder fixed on an ebonite base, and closed at the top by an ebonite
cap. A solid brass rod runs from top to bottom, and near the bottom,
and at right angles to it, is fixed a smaller adjustable rod,
terminating in a flat head. Opposite to this flat disk there is a
brass strip secured to the ebonite cap. From the top of this brass
strip hangs a gold or aluminum foil. The foil and strip are placed to
earth, and the solid brass rod is connected to the circuit to be
protected. Should the difference of potential between the foil and the
terminal opposite to it attain more than a certain amount,
electrostatic attraction will cause the foil to touch the disk and
place the circuit to earth. The apparatus, which is a modification of
the Cardew earthing device, is constructed by Messrs. Drake & Gorham,
of Victoria Street.--_The Electrician_.

[Illustration.]

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EXPERIMENTS WITH HIGH TENSION ALTERNATING CURRENTS.

Messrs. Sieme