The gun trade now depends for support on the demand for--first, cheap muskets for African and other aboriginal tribes; secondly, on cheap fowling-pieces, rifles, pistols, blunderbusses, etc., for exportation to America, Australia, and other countries where something effective is required at a moderate price; thirdly, on the home demand for fowling-pieces of all qualities, from the commonest to those sold at the West End of London, at fancy prices; fourthly, on that for fire-arms required by our army and navy; and, lastly, on occasional uncertain orders created by wars and revolutions on the Continent. There are a vast number of guns, or parts of guns, made in Birmingham, which bear the names of retailers in different parts of the kingdom. Even very fashionable gun-makers find it worth their while to purchase goods in the rough state from Birmingham manufacturers on whom they can depend, and finish them themselves. This is rendered easy by the system. No one in Birmingham makes the whole of a gun. The division of labour is very great; the makers of the lock, the barrel, and the stock, are completely distinct, and the mechanics confine themselves to one branch of a department. The man who makes the springs for a lock has nothing to do with the man who makes the nipple or the hammer; while the barrel-forger has no connexion with the stock-maker or lock-maker. The visitor who has the necessary introductions, should by no means omit to visit a gun-barrel factory, as there are a good many picturesque effects in the various processes, beside the mechanical instruction it affords. The following is the order of the fabrication of a common gun:-- The sheets for barrels are made from scraps of steel and iron, such as old coach-springs, knives, steel chains, horse shoes and horseshoe nails, and sheets of waste steel from steel pen manufactories. These, having been sorted, are bound together, and submitted first to such a furnace, and then to such a steam hammer as we described in our visit to Wolverton, until it is shaped into a bar of tough iron, which is afterwards rolled into sheets of the requisite thickness. From one of these sheets a length sufficient to make a gun barrel is cut off by a pair of steam-moved shears, of which the lower jaw is stationary and the upper weighs a ton, of which plenty of examples may be seen in every steam engine factory. The slip of iron is made red hot, placed between a pair of rollers, one of which is convex and the other concave, and comes out in a semicircular trough shape; again heated, and again pressed by smaller rollers, by which the cylinder is nearly completed. A long bar of iron is passed through the cylinder, it is thrust into the fire again, and, when red hot, it is submitted to the welder, who hammers it and heats it and hammers it again, until it assumes the form of a perfect tube.