It is said that sixty thousand sovereigns and half-sovereigns can be weighed here in a single day. The weighing-machine in question is the invention of Mr. Cotton, a former governor of the Bank, and among scientific men is regarded as one of the most striking achievements of practical mechanics. In the Bullion department we find another weighing-machine of a different character, but in its way equally remarkable. It is the first of its kind, having been designed specially for the Bank by Mr. James Murdoch Napier, by whom it has been patented. It is used for the purpose of weighing bullion, which is purchased in this department. Gold is brought in in bars of about eight inches long, three wide, and one inch thick. A bar of gold of these dimensions will weigh about two hundred ounces, and is worth, if pure, about eight hundred pounds. Each bar when brought in is accompanied by a memorandum of its weight. The question of quality is determined by the process of assaying; the weight is checked by means of the weighing-machine we have referred to. This takes the form of an extremely massive pair of scales, working on a beam of immense strength and solidity, and is based, so as to be absolutely rigid, on a solid bed of concrete. The whole stands about six feet high by three wide, and is inclosed in an air-tight plate-glass case, a sash in which is raised when it is desired to use the machine. The two sides of the scale are each kept permanently loaded, the one with a single weight of three hundred and sixty ounces, the other with a number of weights of various sizes to the same amount. When it is desired to test the weight of a bar of gold, weights to the amount stated in the corresponding memorandum, _less half an ounce_, are removed from the latter scale, and the bar of gold substituted in their place. Up to this point the beam of the scale is kept perfectly horizontal, being maintained in that position by a mechanical break; but now a stud is pressed, and by means of delicate machinery, actuated by water-power, the beam is released. If the weight of the bar has been correctly stated in the memorandum, the scale which holds it should be exactly half an ounce in excess. This or any less excess of weight over the three hundred and sixty ounces in the opposite scale is instantly registered by the machine, a pointer travelling round a dial until it indicates the proper amount. The function of the machine, however, is limited to weighing half an ounce only. If the discrepancy between the two scales as loaded is greater than this, or if on the other hand the bar of gold is more than half an ounce less than the amount stated in the memorandum, an electric bell rings by way of warning, the pointer travels right round the dial, and returns to zero. So delicate is the adjustment, that the weight of half a penny postage stamp—somewhat less than half a grain—will set the hand in motion and be recorded on the dial.