From Gibbon's:
Canister Shot is a tin cylinder with iron heads, filled with balls packed in with saw -dust.
The heads are movable, and the edges of the tin are turned down over them to hold them in
their places. The balls are made of such a size that seven of them can lie in a bed, one in the
middle, and six around, making the diameter of the balls about one -third that of the bore.
These balls are all made of c«t iron, except for the mountain howitzer, the canisters for
which are filled with musket -bullets, which, as has been shown, meet with less resistance
from the air, and retain their velocity longer than cast-iron balls of a much larger size. It
would be better to make them of wrought iron for field-guns, as is done in France; as,
besides being more dense, they would be less likely to break and injure the bore of the gun
than cast-iron ones. For dimensions, see Appendix, p. 444.)
When canister is fired, the balls, having broken the case, escape in the form of a cone, and
striking against each other, and against the sides of the piece, diverge more or less according
to the distance; but the greater part of the balls are found to be near the centre, and the rules
of fire are still based upon. the knowledge of the mean trajectory.
Canister for the Mountain howitzer:
Canister shot may be replaced by filling pasteboard cylinders,
having heads of elm, 1 ½ inch thick -, with musket-bullets placed in beds, and sealed with
good plaster; the weight of the whole not to exceed that of the shot, and to be fired with the
charge of one-fifth of that weight, and not at a greater range than 300 or 400 yards.
Other stuff
Grape and Canister shot leave the piece diverging from each other, in the form of a cone,
the greater part of the balls being in the centre, and the extreme ones separating about
one-tenth of the range. When fired at too short a distance, the balls occupy too small a space
to produce the proper effect; and at too great a distance they diverge too much, and strike on
too extended a surface. Good results can be obtained at from 300 to 600 yards, but the
maximum effect is produced at from 300 to 450 yards. When firing at very short distances
over hard, dry ground, a suitable dispersion of the balls may be produced by firing very low,
and allowing the balls to ricochet.
The range and effect of grape -shot become greater, at ordinary distances, as the size of the
balls is increased. For this reason, the grape from 12 -pdr. guns and 32 -pdr. howitzers, is
more effective than that from 6 -pdr. guns and 12 or 24 -pdr. howitzers, and the 6 -pdr. grape
is no longer used in the United States.*
If the balls ricochet over -hard, dry ground, grape -shot may be effective up to 800 yards, and
the pointing is of but little importance; but with broken or soft ground, ricocheting cannot be
depended on, and the angle of elevation should be regulated with care.
Canister Shot , Fig. 238.-- To form the cylinder for canister shot, the tin is lapped about .5
inches and soldered. It is then fastened to the sabot with six or eight nails, and a plate of
rolled iron is placed at the bottom on the sabot.
The exterior diameter of each canister must be verified with the maximum shot gauge, and
the interior with a cylinder of a diameter 0.02 in. less than that given in the table (see
Appendix, p. 451,) which should enter the canister.
Before filling, dip the cylinder in a lacker of beeswax, dissolved in spirits of turpentine, to
prevent it from rusting. Give the balls and plates a, coat of paint or coal -tar. To fill the
canister, place it upright on its sabot; put in a tier of balls, filling the interstices with dry,
sifted sawdust, packing it with a pointed stick, so that the balls will hold by themselves
when the case is turned over; and throw out the loose sawdust. Place another her of balls and
proceed in the same way until the canister is filled; cover the top her with a layer of sawdust
and put on the cover, which is a circular plate of sheet iron, settling it well with a mallet in
order to compress the sawdust. The top of the cylinder is cut into slits about 5 in. long,
which are turned down over the cover, thus securing it. After it is finished, the diameter of
the canister should be verified with the maximum gauge of its calibre.
