GOLD-WEIGHING MACHINE. In 1843 Mr. Oldham described before the Institution of Civil Engineers the beimtiful Gold-weighing Balance, invented by Mr. Cotton, at that time Governor of the Bank of England. In the transactions between the Mint and the Bank on the one hand, and between the Bank awl the public on the other, scrupulous accuracy is requisite in weighing the sovereigns and half-sovereigns. When there is a coinage of new gold, the gold is conveyed from the Mint to the Bank in parcels called 'journeys,' each journey weighing 15 lbs., and containing 701 sovereigns. A group of 200 sovereigns is accurately weighed, and other groups are then balanced against them, so that the pieces are not counted. The officers of the Mint are allowed an overphis called the 'remedy; amounting to twelve grains in every lb. weight, but they generally work to within one-half of this amount : that is, in two bundles of 150 new sovereigns each, the total weight will not differ so much as six grains.
But it is in the circulation of the gold coins between the bank and the public that the vari eties of weighing arise. It is computed that, at a rough average, 30,000 sovereigns pass over the bank counter every day ; and it is necessary—either as a regular system, or at stated periods—to ascertain how much the coins have lost in weight by the friction of usage. With the old bullion-scales, 4000 sovereigns could be weighed in six hours, and a deficiency amounting only to a of a grain could be de tected ; but the agitation of the air by the sudden opening of a door, the breathing of persons near the apparatus, and many other minute circumstances, were sufficient to dis turb this delicate instrument ; while. the eyes of the teller or weigher became wearied and dimmed, by constantly watching the indicator of the balance, after weighing three or four thousand sovereigns. Mr. Cotton therefore, endeavoured to plan an instrument which while it should be still more accurate than the bullion-balance, might at the same time be easier and more expeditious in use ; and with the aid of Mr. Napier, the Engineer of Lam beth, he completely succeeded.
The exterior of Mr. Cotton's apparatus pre sents a plain brass case, with a small hopper tube on the top plate. About four inches from the hopper there is an opening in the top plate, through which is seen a platform in the shape of a quadrant, suspended above one end of a balanced beam. On one side of the case is a till, to receive the sovereigns as they are weighed ; it is partitioned so that one division is left for standard coin, and the other for such as are light ; and each division has a sliding door, for removing the coins. The hopper
being filled with gold coins, a system of clock work within the machine places a sovereign on the little platform; if the sovereign is of standard weight, a small tongue comes rapidly forward and pushes it into that side of the till allotted to such coin ; if light, another tongue pushes the sovereign into the other side of the till. These tongues act at right angles to each other. While one sovereign is being thus weighed, a succeeding one is on its way from the hopper to the platform ; and the moment the preceding sovereign is dis posed of, another supplies its place. All that the attendant has to do, when the machine is wound up for action, is to keep the hopper supplied with sovereigns, and to remove the weighed sovereigns from the till from time to time. The machine can weigh 10,000 sove reigns in six hours. It can separate into two groups sovereigns which differ in weight by a fraction of a grain so inconceivably small as to be scarcely credible to those who are not ac quainted with the high excellence of this deli cate branch of art.
During the investigation of the Royal Mint Commission, in 1E48, it appeared by the evi dence of Mr. Miller, weighing clerk in the Bank of England, that Mr. Cotton was led to the invention of his machine by an injustice which the bank unconsciously inflicted on'the public. Sovereigns which were issued from one counter at the bank as being full weight, were refused at another counter as being light ; and when this matter was investigated it was found that numerous causes rendered the attainment of uniformity in the action of the bank scales quite hopeless, however small the actual amount of error might bo in each individual case. Between 1844 and 1848 there were 48,000,000 gold coins weighed by Mr. Cotton's machines at the Bank of England ; and the bankers, who pay and receive more coin at the bank than private persons, place undoubting reliance on the accuracy of the I machines. Every sovereign now paid over the counter of the bank, has been passed through the machine before being so paid. The bank, according to the evidence of Mr. Miller, has six of these machines in action, fivo for sove reigns and OM for half-sovereigns ; each of which will weigh 33 coins per minute ! The machines require cleaning once a week—an easy hour's work to each machine. The ma chines cost about 2001. each, and have never yet needed repair. The bank saves about 10001. per annum in wages to weighers, and the public is shielded from unintentional wrong on the part of the bank, by the use of these truly wonderful little machines.