Damascus barrels are made by incorporating alternate layers of red hot steel and iron, which are then twisted into the shape of a screw while at white heat. The bar thus made is twisted in a cold state by steam power round a bar into a barrel shape, then heated and welded together. These are the barrels which present the beautiful variegated appearance which gives them the name of Damascus. The barrels, whether common or twisted, are then bored by a steel rod, kept wet with water or oil, and turned by steam. The process occupies from two to three hours for each barrel. The next operation is that of grinding the outside of the barrel with sandstone wheels, from five to six feet in diameter when new, driven by steam. These stones chiefly come from the neighbouring district of Bilston; in four months' work, a stone of this size will be reduced to two feet. The employment is hard, dangerous from the stones often breaking while in motion, in which case pieces of stone weighing a ton have been known to fly through the roof of the shop; unwholesome, because the sand and steel dust fill eyes, mouth, and lungs, unless a certain simple precaution is taken which grinders never take. After grinding, a nut is screwed into the breech, and the barrel is taken to the proof house to be proved. The proof house is a detached building, the interior of which is lined with plates of cast iron. The barrels are set in two iron stocks, the upper surface of one of which has a small gutter, to contain a train of powder; in this train the barrels rest with their touchholes downwards, and in the rear of the breeches of the barrels is a mass of sand. When the guns, loaded with five times the quantity of powder used in actual service, have been arranged, the iron-lined doors and windows are closed, and a train extending to the outside through a hole is fired. Some barrels burst and twist into all manner of shapes; those which pass the ordeal are again examined after the lapse of twenty-four hours, and, if approved, marked with two separate marks, one for viewing and one for proving. The mark for proving consists of two sceptres crossed with a crown in the upper angle; the letters B and C in the left and right, and the letter P in the lower angle. For viewing only, V stands instead of P underneath the crown, the other letters omitted. After proving, the jiggerer fastens the pin, which closes up the breech. In the mean time the construction of the lock, which is an entirely different business, and carried on in the neighbouring towns of Wednesbury, Darleston, and Wolverhampton, as well as in Birmingham, has been going on. The gun lock makers are ranged into two great divisions of forgers and filers, beside many subdivisions. The forgers manufacture the pieces in the rough, the filers polish them and put them together. In the percussion lock, there are fifteen pieces; in the common flint lock, eight.