The fillets thus prepared are passed to the tryer, who, with a hand-punch, cuts a trial blank from each, and weighs it in a balance; and if it vary more than of a grain, the whole fillet is rejected: For cutting out the blinks of which the coins are to he made. there are in the British mint 12 presses arranged in a circle, so that one wheel with driving cams, placed in the center, works the whole. The puneheS descend by pneumatic pressure. and the fillets are fed into the presses by boys, each punch cutting out about 60 blanks a minute. The scrap left after the blanks are cut out, called aloe& is sent back to be remelted.
Each blank is afterwards weighed by the automaton balance—a beautiful and most accurate instrument, which was added to the mint about 20 years ago. It weighs 23 111.1111.-, ...4" SxJ .... 1 Lt. , I...US,. LA/ LIM, 0.01 of a grain. The standard weight of a sovereign is 123,274 grains, but the mint can issue them above or below this to the extent of 0.2;168 of a grain, which is called the remedy. Bluulis which conic within this limit are dropped by the machine into a " medium" box, and pass on to be coined. Those below the required weight are pushed into another box to be remelted, but those above it into dtother, and are reduced by filing. The correct blanks are afterwards rung on a sounding iron, and those which do not give a clear sound are rejected as dumb.
To insure their being properly mill ed on the edge, the blanks are pressed edgeways in a machine between two circular steel-plates, which raises the edges, and at the same time secures their being perfectly round. After this they are annealed to soften them, before they can be struck with dies; they are also put into a boiling pot cf , dilute sulphuric acid, to remove any oxide of copper frdm the surface. Subsequently they are washed with water, and dried with great care in hot sawdust, and finally in an oven at a temperature slightly above boiling water. Without these precautions, the beautiful bloom upon new coin could not be secured.
We now conic to the press room, where the blanks receive the impres• sion which makes them perfect coins. The coining press is shown ill the fig., and there are eight of them in all, ranged in a row upon a strong foundation of masonry. outs is the massive iron frame into which the screw D works, the upper part B being perforated to receive it. On the bottom of this screw the upper steel die is f13:1-0 by n. hew the lower die being fixed in another box attached to the base of the press. The dies have, of course, the obverse and reverse of the coin upon them. See Dui SINKING. The blank coin is placed on the lower die, and receives the impression when the screw is turned round so as to press the two dies forcibly towards each other. A steel ring or collar contains the while it is being.stamped, which preserves its circular farm, and also effects the milling on the edge. In cases where letters are put on the edge of a coin, a collar divided into segments working in center-plus, is used. On the proper pressure being applied, the segments close round, and impress the letters on the edge of the coin.
The screw of the press is put in motion by means of the piece A, which is worked by machinery driven by steam-power, and situated in an apartment above the coin ing-room. The steam-engine exhausts an air-chamber, and from the vacuum pro duced, an air-engine works a series of air-pumps, which communicate a more exact and regular motion to the machinery of the stamping presses than by the ordinary con densing engine. The loaded arms RR strike against blocks of wood, whereby they are prevented from moving too far, and run the risk of breaking the hard steel dies by bringing them in contact. The press brings down the die on the coin with a twisting
motion, but if it were to rise up in the same way, it would abrade the coin; there is, in consequence, an arrangement winch, by means of a wide notch in the ring 3, allows the die to be raised up a certain distance before it begins to turn round with the screw.
On the left side of the figure, the arrangement for feeding the blanks and removing the coins as they are stamped, is shown. A lever RIK, moving on a fulcrum 1, is sup ported by a bar Q, fixed to the side of the press. The top of this lever is guided by a sector, 7, fixed upon the screw D. In this sector there is a spiral groove, which, as the screw turns round, moves the end H of the lever to or from the screw, the other end K being moved at the same time either towards or away from the center of the press. The loivei end of the lever moves a slider L, which is directed exactly to the center 01 mile press, and on a level with the upper surface of the die. The slider is a thin steel-plate in two pieces united by a joint, and having a circular cavity at the end, which, when its limbs are shut, grasps a piece of coin by the edge. This piece drops out on the limbs separating. There is a tube at K which an attendant keeps filled with blank pieces; it is open at the bottom, so that the pieces rest on the slider. When the press is screwed down, the slider is drawn back to its furthest extent, and its circular end- comes exactly beneath the tube. A blank piece of coin now drops in, and is carried, when the screw rises, to the collar which fits over the lower die. The slider then returns for another blank, while the upper die descends to give the impression to the coin. Each time the slider brings a new blank to the die, it at the same time pushes off the piece last struck. An arrangement of springs lifts the milled collar to inclose the coin while it is being struck.
It is found on examining the coins that about 1 in 200 is imperfectly finished; these being rejected, the rest are finally weighed into bags, and subjected to the process of pyxing. This consists in taking from each bag a certain number of sovereigns or other coins, and subjecting them to a final examination by weight and assay, before they are delivered to the public.
MINT (ante). The first U. S. mint was established at Philadelphia by the coinage act of April 2, 1792; and the first production of the new mint was the copper cent of 1793. Silver dollars were first coined in 1794 and gold eagles in 1795. Branches of the Philadelphia mint were organized at New Orleans, Dahlonega, Ga., and Charlotte, N. C., in 1835; at San Francisco, Cal., in 1854, and at Carson City, Nev., in 1870. Those at New Orleans, Dahlonega, and Charlotte have been given up. Assay offices were set up at New York in 1854, at Denver in 1864, and Boise City, Idaho, in 1872. The act of April 1, 1873, put all the mints and assay offices on the same footing as a bureau of the treasury department, under the superintendence of the director of the mint, who is appointed by the president fora term of 5 years, and is under the supervision of the sec retary of. the treasury. The director of the Philadelphia mint, who had hitherto been called director of the mint, was now known as superintendent of the Philadelphia mint. Every mint has a superintendent, melter and refiner, assayer, and coiner, and the Phila delphia mint has an engraver, who supervises the manufacture of the dies used in all the U. S. mints. The total production of the mints for 1880 was: gold coin,$56,157,735.00; silver, .27,942,437.50; minor coins, $269,971.50. The present director of the mint (1881) is Horatio C. Burchard, of Illinois.