We now come to the third subject—the actual manufacturing pro cesses. The mode of coinage in early times, at least in this country, as far as it can now be traced, was rude and inartificial; the sole expedient employed being to fix one die firmly in a wooden block, and to hold the other in the band as a puncheon ; when, by striking the latter forcibly, and repeatedly, with a hammer, the impression required was at length worked up. This method appears to have been nearly coeval with the first invention of coined money ; and it is a singular fact that no improvement of any importance was made in it, until the power of the screw was applied to coinage in the French mint about the middle of the 16th century. (Le Blanc, Traits Hist. de Monnoyes de France.') The present mode of proceeding at the Mint may be briefly described as follows : When ingots of gold arrive at the Mint, they are carefully weighed, the weight registered, and a receipt given. Assay pieces are cut from them ; and they are assayed, to ascertain exactly how much the gold is above or below standard, if at all. They then pass to the melting house, where the inciter weighs them, and gives a receipt for them. Each ingot is about 8 inches long, 3 inches wide, and 1 inch thick ; if the gold be standard, the value is about 800/. ; and to bring it to standard, an amount of alloy is added depending on the result of the assay. Six ingots, with the necessary alloy, are put into one crucible; and ecveral such crucibles are placed in seven charcoal-heated furnaces. Numerous cast-iron moulds are arranged in a frame ; the molten gold is poured into these ; and when cold, each mould is opened, and a bar of gold taken out, 21 inches long, 1 inches broad, and 1 inch thick, if for sovereigns ; but somewhat longer and narrower if for half-sovereigns. If for silver coinage, the ingots are 13 inches long, 5 inches wide, and 4 inches thick, valued at about 250/. ; the weighing, assaying, melting, and casting into bars, are nearly the same as for gold, but requiring larger apparatus, on account of the greater weight of metal operated upon. The bars into which the silver is cast are 21 inches long, from to 2,1 inches wide, and from to 1 inch thick, according to the kind of coins to be made. The bars are then transferred to the rolling-mill. The machinery next brought into use is of a very powerful character, worked by steam-engines recently set up by Messrs. Hall. There are six pairs of rolling-cylinders, varying from 14 to 10 inches in diameter, all with hardened steel surfaces, and highly polished. Every bar is passed many times through the rollers, which are brought closer and closer to accommodate the reduced thickness. The bars, thus length ened to 7 or 8 feet, are cut into five pieces each; then annealed in a furnace ; then rolled again ; and so on—until brought to the respective thicknesses for the different kinds of coin ; or rather, slightly in excess of that thickness. All these operations are nearly the same in character for silver and for copper coins as for gold.
The fillets of gold are then transferred to the flatting-mill, where they are passed between rollers exquisitely adjusted, so as to make the fillet uniform in thickness in every part, and exactly thick enough for a sovereign or half-sovereign. Trial-blanks cut from each fillet must not vary in weight more than ith of a grain, or the whole fillet is rejected. The cutting-out of a small number of trial-blanks is effected by a hand-punch ; but the cutting-out of the blanks which are to form the coins themselves is the work of twelve powerful presses ranged in a circle. The fillets are fed into each press by boys ; and stamps, worked
by pneumatic power, speedily cut them up into blanks. Each machine cuts out as fast as a boy can feed it (about 60 per minute); and in busy times the whole twelve presses cut about 200,000 sovereigu-blanks per day. The scrap or wind is sent back to the melting-house. After another careful weighing and registering, the blanks are tied up in bags and sent to the weighing-room. Men used to be employed, under the name of sizera, to weigh each blank separately ; but in 1855 twelve exquisite automatic weighing-machines were introduced, the invention of Captain (afterwards Colonel) Harness, the deputy master. Machines of somewhat similar character had been before invented by Mr. Cotton, to be used for sovereigns at the Bank ; but those now adverted to are for blanks. The blanks are fed into each machine through a spout ; a slide pushes each blank upon a delicate balance, where it remains exactly three seconds to poise itself ; if correct in weight to 1th of a grain, another slider comes forward and pushes it over the edge into a " medium " or correct box ; while the few, very few, which overpass this limit in either direction, are pushed into a " heavy " or "light" box, as the case may be. Under the sedulous care of Colonel Harness and Professor Graham, the rolling, drawing, and cutting-out are now so accurately performed that 98 or 99 blanks fall into the " medium" box out of every 100. All blanks for gold coins, and all for silver coins except those of very small denominations, are now tested by these beautiful machines; these small coins are tested at so many to the ounce, and copper coins at so many to the pound—or, at least, the blanks for them. The weighed blanks are then passed to the marking machines, which are eight in number ; these, by a very peculiaimove ment, so roll the blanks as to make the peripheries perfectly circular, and to raise a slight projecting edge on each surface—not to produce a milled edge, but to facilitate the stamping. After this, the blanks are annealed by being exposed to a cherry-red heat for a few minutes ; they are next cooled in water, pickled or blanched in dilute sulphuric acid, dried with heated beech-wood sawdust, and made up into journeys, or bags of definite weight, which in the case of sovereign-blanks amount to 15 lbs. troy, or 701 pieces.
The blanks are next coined or stamped. The coining-presses, eight in number, are very strong and massive, having to bear a great strain during the operations. Rouleaux or piles of blanks are supplied to a tube, from which they one by one fall upon the lower die, supported by an anvil ; the upper die is brought down upon the blank by a peculiar combination of screw-power and pneumatic power, and a sovereign stamped on both sides falls out, milled, too, at the edge. An analogous process, varied only in details, is employed for other coins.
If all the eight presses are fully in action, they will stamp 200,000 coins per day. After being once again weighed,, the sovereigns are put up in bags of 701, and these in larger parcels of 5608. On the day after being stamped, the sovereigns are conveyed to a central office, where they are pixed, or officially tested. If medals instead of coins are being struck, the operations are lengthened by this circumstance- that, on account of the high relief of the device, every blank requires many blows and many annealings before it can receive the full effect of the impression.