Detonators
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        The most common time-delay device is an ordinary safety fuse. These
fuses usually consist of a black-powder core surrounded with a fabric and
then a layer of waterproof material. Although there are many different types, 
it can generally be said that safety fuses burn between 30 and 45 seconds
per foot; however, check these figures when you make your purchase. Fuses
can be bought from any mail-order pryotechnics company. Two with whom I have
dealt are:
        Ecco Products
        Box 189
        Northvale, New Jersey 07647

        Westech Corporation
        P.O. Box 8193
        Salt Lake City, Utah 84108

        Double-coated waterproof fuse usually sells for 20 to 25 dollars for
a thousand to fifteen hundred feet. I would advise purchasing this equipment,
since homemade fuses are not to be trusted.
        Bombs can be detonated in many ways. The detonation and use of
certain devices are based mainly on the cleverness and imagination of the
saboteur. In the following section I have discussed several basic forms of
detonators, both nonelectric and electric. However, there is an infinite
number of variations, which may be better suited to individual situations.
        The first type is referred to either as a tension-release, or a
wiretrap device. It operates on the principle of releasing the tension 
caused by a wound spring, on the firing pin, and allowing it to strike and
set off a nonelectrical blasting cap. The nonelectrical blasting cap will in
turn generate the necessary heat to ignite the TNT or dynamite. This can be
implemented in many ways. A common method in which the wire-trip device can 
be employed is stretching a trip wire six inches above the ground. Another 
equally popular method of employing the tension-release device is attaching
the taut wire to the back of a door, so that, when the door is opened, the
tension is released, and the explosive ignites.
        A device very similar to the last one is the pull-trigger electric
detonator. It functions in the same manner, in that a safety pin is removed
from the striker or firing pin, causing it to move forward and connect with a
metal plate. This connection with the metal plate completes the electrical
circuit. The batteries have been connected by wires to an electrical 
blasting cap, a metal plate, and finally to the firing pin. Although 
professional supplies for this equipment are available at reasonable prices,
the device can be constructed from household items. The construction of this
device is as follows: two flashlight batteries are connected to each other,
and then one wire is run from one end of the batteries to the electrical
blasting cap, the other wire from the opposite end of the batteries to the
metal plate. A third wire is run from the blasting cap to the firing pin.
This now completes the fully cocked device.
        In the same manner as the explosive is detonated, so is the common
military grenade. The principle of a tension release is the same. After the
pin is pulled out of the military grenade, the spring is free to react,
causing the primer to ignite the lead-spitter fuse, and it in turn will ignite
the lead oxide and pentolite. The pentolite will release enough heat to
ignite the TNT and cause fragmentation of the metal casing.
        The next type of detonating device I am going to discuss is called the
pressure-trigger device. It is based on the application of pressure rather
than its release, as in the previous devices. This mechanism is primarily
used when an electrical circuit is employed. The plunger is pushed down; it
forces one thin metal plate against another thicker metal plate. The batteries
are connected, via the blasting cap, to each of these metal plates. Therefore,
when they touch, the electrical circuit is complete, and the explosive will
ignite.
        This type of device has several important advantages. First of all,
it can be constructed away from the area it will be used in. This will cut 
installation time down to seconds. Later the in the chapter, I discuss a
type of booby trap that can be rigged into the ignition system of a car.
Although the ignition-system booby trap works very well, it takes time to
install. This pressure-trigger device will act almost in the same manner if
placed beneath the drivers seat, and can be installed in a lot less time.

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