, and the
time required for the projectile to pass over this distance is
determined by finding the difference in the time of cutting of the two
targets, by finding the difference in the time of falling of the two
rods, caused by the demagnetization of two electromagnets in the same
circuit with the targets.
By means of a disjunctor both rods are dropped at the same time, the
shorter one releasing a knife blade which makes a cut on the longer
one. Now both rods are hung from the magnets again and the gun is
fired.
The projectile passes through the first target, breaks the circuit,
demagnetizes the magnet of the longer rod, and it begins to fall. On
passing through the second target, the projectile causes the shorter
rod to fall. This releases the knife blade, and a second cut is made.
The time corresponding to the distance between these cuts is the time
the longer rod was falling before the second rod began to fall or the
time between the cutting of the two targets by the projectile.
The distance between the cuts is measured, and the time corresponding
to it can easily be found. Then the velocity of the projectile is
equal to 50/t.
To repair this target, strings are prepared in advance of suitable
length and looped at both ends, so that by placing the hook of the
cartridge in one loop and that of the weight in the other the repair
is quickly made.
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