Reports recently received from credible sources, describe a German trip-wire
alarm which gives warning of movement of patrols or individuals in areas
where the Germans have erected wire defenses.
Although complete details concerning the equipment are not available, it
appears (see accompanying sketch) that the device consists of a box (1) with a neck
at the top into which the alarm cartridge (2) fits. Through the bottom passes a
striker, with a T-shaped head (3) by which it may be pulled down against a spring
A spring-equipped, right-angle lever (4), pivotted at the top (5) is forked
on the horizontal part which passes beneath the box and holds the striker pin in
the cocked position. To the center of this lever is fastened a clamp (6) whose jaws
grip the trip wire. This wire may be a strand of the existing wire defenses, a
special trip wire, or one of the wires used in the construction of an obstacle.
The alarm cartridge (2) is of signal cartridge type, 83-mm (3 1/4 inches)
long and 27-mm (1 1/16 inch) diameter. It weighs 2 1/2 ounces. The body is
painted black. Its recognition by feel is easy since its sealing disk (7) extends
over the outside, and the rim (8) of the base is half smooth and half serrated.
A picket (9) is driven into the ground near the wire. Then the alarm device
is well-lubricated and slipped over the picket and fastened to it by
clamps (10). By positioning the retaining ring (11) the equipment is held at such a height that
the clamp (6) engages the wire. The wire is placed between the jaws of the clamp
and locked in such a position that it is not under tension and does not move the lever.
Slight pulling or pushing of the wire should, however, be sufficient to operate the
The alarm is tested by pulling down the T-shaped head (3) until the cocking
stop engages with the fork of the lever (4). Then, if the wire is moved slightly,
the striker pin should rise.
The alarm is loaded by pulling down the retaining spring and side wall (12)
and sliding the alarm cartridge in from the front, over the striker pin. The device
is then cocked by pulling down the T-shaped head (3) until the cocking stop engages
with the fork of the lever (4), in the same manner used in testing. Now, however,
the trip-wire must not be touched.
When the alarm cartridge is fired, a flame is ejected from the cartridge.
The flame will rise to a height of about six feet, it will burn for
about 10 seconds and at night will illuminate an area
with a radius of about 50 feet.