The manufacture of these fire-arms presented some practical difficulties which could only be overcome by great care and skill in the construction; and from the failure in this respect they were not patronized. It was necessary, in the first place, that the loaded chambers should be brought into an exact line with the barrel, and be firmly retained there during the discharge. It also required great nicety in the fitting of the breech to the barrel, to prevent the fire from communicating to the other chambers. A further difficulty was to prevent the spindle, whereon the breech revolved, from becoming foul by the explosion of the powder; otherwise, after firing a few times it would stick fast, and the gun would become useless. The earliest patent for repeating fire-arms in this country was obtained by James Puckle, in 1718, for a gun with a rotating breech. There were six chambers in the breech, which was turned round by a winch, and, when the six were fired, there was an arrangement by which the chambered breech could be removed, and another loaded one substituted for it. Mr. Puckle appears to have been of a poetical turn of mind, and the specification of his patent is enlivened by the following loyal couplet, which deserves to be quoted as a novelty in patent records:-- "Defending King George, our country and laws, Is defending yourselves and the Protestant cause." The invention of percussion priming in 1800, by the Rev. A. J. Forsyth, was an important step towards the perfection of fire-arms generally, and of Revolvers in particular; for until the chambered breech could carry round with it in a compact form the priming for each chamber, the construction must have been clumsy, and the action uncertain. Colonel Colt, as already stated, took out his first patent in 1835, and in 1849 he patented the improved Revolver, which he has brought into general use. It has six chambers in the rotating breech, and the nipples to hold the percussion caps are sunk into a recess, so that the lateral fire, if any, cannot reach them; and at the other end, the chambers are protected from lateral fire by chamfering their mouths. By these means, the danger of firing the gunpowder in the other chambers is effectually provided against. The demand for Colt's Revolvers became so great after the last improvements were made, that at his manufactory, at Hartford, in America, he made 53,000 of them in 1853; and at his manufactory at Vauxhall, near London, he employs upwards of 300 workmen, though by far the largest portion of the work is done by machinery. Several improvements have been introduced in Revolvers since Mr. Colt's patent of 1849, among which is the arrangement, made by Mr. Adams in 1851, for causing the chambered breech to turn by the action of pulling the trigger, which at the same time draws back the hammer. By this arrangement, the whole of the six loaded chambers may be discharged in three seconds, whilst the pistol continues presented.