Per-cus′sion-cap.
A small cylinder of copper adapted to fit on the nipple of a gun and having a flake of fulminating powder inside, which is exploded by the fall of the hammer upon the nipple, communicating fire through the latter to the charge in the gun.
Detonating powder or pellets were used in 1807, having been patented in
England by
Rev. Mr. Forsyth for use with artillery; but the charging of caps therewith was a later invention.
The percussion principle had a hard struggle with the old flint-lock in the armies of
Europe and
America until long after it was universally adopted for sporting purposes.
It was not introduced into the
United States service until 1842.
Caps were invented in
England in 1814 by
Joshua Shaw.
He came to the
United States for the purpose of procuring a patent, but was refused as an alien.
In 1822, he patented a percussion-lock; in 1828, the percussion-wafer primer.
He subsequently received $17,000 from the United States government for his improvements, and died in 1860.
Caps for smallarms are made of thin sheet-copper, those for sporting guns, etc., usually having longitudinal striations.
The composition used in the
United States service is fulminate of mercury mixed with half its weight of niter.
This renders the fulminate less explosive, and gives body to its flame; it is protected by a drop of copal varnish, which soon dries in a thin film, preventing access of decomposing agents.
Tin-foil is also employed for the same purpose.
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1665]
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Percussion-cap filling-machine. |
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Percussion-cap filling-machine. |
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Percussion-cap holder. |
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Percussion-cap trimmer. |
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Percussion-fuse. |
In the
British service, a composition of 6 parts fulminate of mercury, 6 chlorate of potash and 4 antimony, is used.
The machines for making caps display great ingenuity.
In
Boughton's they are stamped from strips of copper previously cut to proper widths, and then charged with the composition.
Wright's machine cuts the blanks from the sheet, forms, and charges them with fulminate at one continuous operation.
The varnish is applied by a very simple device to a whole row of caps arranged in holes in a board.
Percussion-caps of paper, fitting on the hammer, were formerly used for cannon, but have been superseded by quill-tubes and friction-primers.
Separate caps for military purpose are now mostly disused, having been superseded by the modern capped metallic cartridge, in which the fulminate is applied inside the base of the shell, forming a ring in rim-fire cartridges or a cap in the center of central-fire cartridges.
With many of the latter class detachable caps are used, which are inserted from the outside in a depression in the base of the shell.
See cartridge.
