The upper shaft, on which are seen the three large wheels, has also fastened to it, over each press, an eccentric wheel. In the first illustration will be seen three upright rods running from near the table to the top. The middle one is connected with a tire around the eccentric wheel, and rises and falls with each revolution. The eccentric power gives great rapidity of motion with but little jerking. The operator places one end of a strip of metal in the immense jaws of the press, and cuts out a couple of planchets, which are a fraction larger than the coin to be struck. As the strips are of uniform thickness, if these two are of the right weight, all cut from that strip will be the same. They are therefore weighed accurately. If right, or a little heavy, they are allowed to pass, as the extra weight can be filed off. If too light, the whole strip has to be re-melted. As fast as cut the planchets fall into a box below, and the perforated strips are folded into convenient lengths to be re-melted. From a strip worth say eleven hundred dollars, eight hundred dollars of planchets will be cut. ADJUSTING ROOM. [Illustration: DELICATE SCALES.] The planchets are then removed to the adjusting room, where they are adjusted. This work is performed by ladies. After inspection they are weighed on very accurate scales. If a planchet is too heavy, but near the weight, it is filed off at the edges; if too heavy for filing, it is thrown aside with the light ones, to be re-melted. To adjust coin so accurately requires great delicacy and skill, as a too free use of the file would make it too light. Yet by long practice, so accustomed do the operators become, that they work with apparent unconcern, scarce glancing at either planchets or scales, and guided as it were by unerring touch. The exceedingly delicate scales were made under the direction of Mr. Peale, who greatly improved on the old ones in use. So precise and sensitive are they that the slightest breath of air affects their accuracy, rendering it necessary to exclude every draft from the room. PROGRESS IN COINING. The methods of coining money have varied with the progress in mechanic arts, and are but indefinitely traced from the beginning; the primitive mode, being by the casting of the piece in sand, the impression being made with a hammer and punch. In the middle ages the metal was hammered into sheets of the required thickness, cut with shears into shape, and then stamped by hand with the design. The mill and screw, by which greater increase in power, with finer finish was gained, dates back to the Sixteenth Century. This process, with various modifications and improvements, continued in use in the Philadelphia Mint until 1836. [Illustration: ANCIENT COINING PRESS.]