LOCK of a g-un is that apparatus by which the powder is fired. Muskets, in their earliest use, were fired by the hand applying a slow match to the touch-hole. Towards the end of the 14th c., the first improvement appeared in the matchlock,. This consisted of :t crooked iron lever, in the end of which the match was fixed. By a pin-gear of a simple nature, pressure on the trigger brought the match accurately down on the powder pan, of which the lid had previously been thrown forward by the hand. This mode of firing involved the carrying of several yards of slow match, usually wound round the body and the piece; rain extinguished the match, and wind dispersed the powder in the pan, so that the matchlock, clumsy withal, was but an uncertain apparatus.
Superior to the matchlock was the introduced at Nuremberg in 1517, in which tire was produced by friction between a piece of flint or iron pyrites and a toothed wheel. The mechanism which generated the sparks simultaneously uncovered the pan, so that the dangers from wind and rain were averted; but, before firing, the apparatuS required to be wound up like a clock, and therefore the charges could not be frequent. The wheel-lock continued for a long period to be used in Germany, and partially in France. In the Spanish dominions, however, its place was supplied. by the simplci contrivance called the Snaphauuce, Snapphahn, or Asnaphan lock, of nearly contempo raneous invention, which, acting by means of a spring outside the lock-plate, produced fire through the concussion of a flint against the ribbed top of the powder-pan. Its posi tions of half and full cock were obtained by the insertion of a pin to stay the operation of the main-spring. In the middle of the 17th c. the/lint-lock was invented, combining the action of the wheel-lock and the snaphaunce, while it was incontestably superior to either. After combating much prejudice, it was universally adopted in the armies of western Europe by the commencement of the 18th century. Muskets embracing it obtained the name of " fusils," a French adaptation of the I talian word focile, a flint. With successive improvements, the ffint-lock continued in general use until the introduction of the ahnost in our own day; and ninon; eastern and barbaric nations the ffint-lock is still extant. Its great superiority over ihe snaphaunce consisted in the
" tumbler " (of which presently) and the "seem.," appliances still retained in the percus sion lock, which enabled the positions of half and full cock to be taken up without the intervention of pins, always uncertain in their action.
The principle of the percussion-loelc is the production of fire by the falling of a hammer upon detonating powder, the explosion of which penetrates to the charge in the barrel of the gun. The tirst practical application of this principle to lire-arms is clue to the rev. Mr. Forsyth of Belhelvie, in Aberdeenshire. Various forms in which to in-nite the detonating powder have been devised, bin that generally accepted until within the• last few years was the copper-cap, fitting tightly on the nipple of the gun, charged with a detonating compound, and exploded by the hammer falling upon it. The main-spring counnunicates through the swivel with the tumbler, which concentrically with the hammer moves on the tumbler-nail. After the hammer has delivered its stroke, its fur ther progress in the direction required by the spring is barred by the nipple. On pulling back the hammer to the position of half-cock the tumbler turns with it, and the pointed end of the scear (which moves on the scear-nail as center), influenced by the scear-spring, falls into a notch in the tumbler. On forcing back the hammer to full-cock, however, the scear will move down to a shallower notch; and on the lever end of the scear being raised by the trigger, it brings down the hammer with a heavy blow on the cap. To keep the works firmly in their several places, a "bridle" is screwed over them which includes the pin through the tumbler in its width.
Since the adoption of breech-loading arms, the action of the lock is so far varied that the hammer usually falls on a movable pin, which is impelled against a detonating charge placed in the body of the cartridge itself. A spiral spring around the pin brings it back to the position necessary for another blow. The advantage of this arrangement is that one operation of loading is substituted for the double process of loading and capping.