Chapter III: Part 3

Fig. 11 represents the _draw-bench_, the name of which is retained, as being in fact its only appropriate one. The _flatted_ end of each fillet is passed into the opening shown at A. The _dog_ A´ is then run up till its teeth seize the fillet. The lever is depressed until one of the hooks O catches a bar of the circulating chain P, which in its onward motion drags the dog, and causes it to bite the fillet and _draw_ it through the opening at which it has been entered. P gets its motion from a notched cam, the axle of which is shown at Q. There are two distinct chains to each draw-bench, and there are two distinct draw-benches, so that one description does for both double ones. R is a cogged wheel, the shaft of which, Q, carries two notched drums, and each drum gives motion to a chain, so that both chains travel at the same pace. R is set in motion by the pinion S, on the shaft which is driven by the wheel T. T is driven by U, which is on the shaft driven by the strap and drums V. Fig. 12 is a representation of the head of the draw-bench, and in studying this engraving it will be well to refer at the same time to Fig. 11. The dog takes its name from its resemblance to the head of a bull-dog. It consists of a pair of levers, whose long arms extend beyond the axle-tree of the wheels nearest to O, and whose shortest arms are formed by the passing of the other axle-tree through the lever. The teeth are set at the front of the short arms. The axle-tree near O is fixed to the bars forming O, and runs loosely between the long arms of the lever, so that when O is pulled forcibly it causes the axle-tree to open the long end of the levers, and thereby to close the short end or teeth of the dog, the more rigidly in proportion to the pressure exerted at O. Directly the fillet has passed through the cylinders the dog springs slightly by the elasticity of the fillet, and thus releases itself from the chain; at the instant of release the weight over the foremost wheels falls, and by its fall lifts the hooks O so high as to admit of their escaping contact with the circulating chain P. The position of the teeth of the dog is shown by A in Fig. 12. The flatted part of the fillet is just so thin as to admit of its passing easily between the cylinders B until seized by A, but the part which is not thinned comes against the cylinders B, and requires considerable force to drag it between them. The cylinders B do not rotate; in fact, they may be considered as forming part of a solid mass.[20] The lower cylinder is laid on the bed C, and is clamped there by a cheek fastened on to C by three screws, the holes for which are shown on C; the upper cylinder is fixed to the mass D by a precisely similar arrangement. The beds C D are held perpendicularly by the points of the screws E; and we may now view the cylinders as secured to, and forming part of, their beds. The distance between the cylinders is regulated by the capstans F, which separate the beds of the cylinders, and so separate the cylinders. The accuracy of this adjustment is all-important, because the distance between the cylinders determines the thickness of the fillet which passes between them. The bed D of the upper cylinder is required to be movable at pleasure; it is therefore provided at G with four wedges, two of which, _c c_, are cut so that if looked upon from the top a round hole shows itself, and through this hole the end of the screw, which at this point L is plain, and has a neck turned in it, passes, with its head beneath the wedges and against the lower G. So soon as this is effected the wedges A B are pressed into their places, and these holding _c c_ together, cause them to secure G by its neck; if, therefore, G be now caused to rise, the block D must rise with it, but the head of this screw rests on the solid block D, while its neck is just so long as to admit of this without itself being pressed against the wedges _c c_. G is a very fine-cut screw which fits into a female screw cut in the frame of the head of the draw-bench; it is moved to any distance varying from the hundred-thousandth part of an inch (0·00001) and upwards by the wheel H, which receives a very minute motion from the pinion I by means of a lever fitting into the capstan head J. K was originally intended to be used to set or fix the screw G when it had been brought to its proper position, but it is not used; for, in fact, the cylinders wear away appreciably by the passage of the fillets, so that they constantly require to be brought nearer together to make up for this wear. With some species of gold the friction is so great that, although oil is used, the cylinders become so hot as to render the gold pasty; in such case a kind of welding takes place, which causes the tearing of the fillet. If this extreme point be not reached, as indeed it seldom is, the cylinders become of varying temperatures, and so great is the effect of this, that in order to compensate for it, the upper cylinder has to be continually raised or depressed. The beds which carry the cylinders become worn by the strain and fret, and require grinding out at intervals; therefore, to allow for the difference which this would make, screws N are provided, by which the cylinder in the lower bed can always be raised to its proper position. We cannot but admire the ingenious productions of inventive minds; and surely if ever there were a marvellous machine for assisting the coiner, it is this; indeed, it may be doubted whether a more admirable instrument for its purpose can be contrived. Sir John Barton, who invented and directed the making of it, took into consideration every circumstance which could possibly arise, but he never saw practically the full advantage of his conception. Under my direction, this machine was so used that the average work produced was very favourably compared with the trials recorded by Sir John Barton, and details of which were given to me by the late Mr. W. H. Barton. There are some persons who smile at the draw-bench, but it is one of those inventions which will outlive its detractors, at least, so long as economy and perfection are points to be studied in coining. Foreign Mints are said to have found no advantage in the use of the draw-bench. It is to be regretted that they have not found a man with sufficient intelligence to use so accurate an instrument; it is surely not the fault of the sun if men are blind to its splendour. Mr. J. Martin, of the Paris Mint, has recently made some very accurate experiments with the draw-bench, and has produced results every way in accordance with those obtained by me in the Royal Mint, and is convinced that the draw-bench may be considered as the coiner’s right hand.

[Footnote 20: As the cylinder wears, the screws of C may be loosened to permit the shifting of the abraded part, so that the whole circumference of the cylinder may be used.—See also page 31.]

Against all sound advice the Master had been induced to buy a pair of steel rollers, at a cost of £800 (I state the sum on the authority of Mr. W. H. Barton, who, being Comptroller at the time, probably knew the actual cost), and with these I made an elaborate series of experiments, extending over many weeks. The results were wholly adverse to the new rollers—others arrived at the same conclusion—and I reported to the Master, in writing, on the facts as I found them, showing that the average gave an advantage of 19·92 per cent. in favour of the draw-bench, and on this ground I maintained the superiority of that machine. He replied by a peremptory order, directing me “to prohibit now and for ever” the “use of the draw-bench, and to take measures for its removal from the Mint.” Thus absolved from responsibility, I—after making a written protest—obeyed that which I could no longer withstand. The result was that the rejected blanks, which had averaged 3·60 per cent., now advanced to 23·52 per cent. I was unable to avoid this great expense, and when I spoke to him about it he was not very amiably disposed; however, he finally wrote me the following note, on which I remarked to him “that steel rollers, whether driven by cogged wheels or by straps, would still be steel rollers.”

“_7th June, 1861._

“DEAR SIR,

“In the cutting and adjusting room you may return to the use of
the draw-bench till the gearing of the steel rollers is altered.
I had overlooked the circumstance that in the United States Mint
cogged wheels are not used for that purpose.

“Yours truly,
“THO. GRAHAM.
“G. F. Ansell, Esquire.”

It is satisfactory to me to find that Mr. Fremantle confirms the opinion at which I had arrived. He says (“European Mints,” page 9):—“The adjustment of the fillets after rolling is in some European Mints performed by the draw-bench, as in England. In others it is performed by carefully adjusted rolling mills only. The experience acquired both in this country and abroad tends to show that it is advisable to retain the draw-bench—at any rate, until some more accurate method is found of equalising the fillets and reducing them to their correct thickness.” If Mr. Fremantle will investigate for himself instead of being guided by the opinions of others, he will rigidly follow the correct conclusion at which he has arrived; if, however, he will look in the drag room in the Royal Mint, he will discover evidence of the former existence of a series of rollers which were replaced by the draw-bench. Yet one of his co-travellers, who is manifestly willing to make experiments, says of the draw-bench, “Still it has yet to be proved that it can compete in sustained accuracy with a well-constructed rolling mill.” Quite true; but I think the answer holds good, and any one who would replace the draw-bench by rolling mills—which have hitherto failed—should, as Sir John Barton did, prove his proposition otherwise than at the Government expense, and then on success obtain fair remuneration. Before leaving the study of this instrument it is right that I should mention that Mr. John Murray, of the Royal Mint, has added immeasurably to the value of it by inventing a most ingenious machine for grinding the cylinders (see B, page 28) with accuracy, so that those cylinders which have been used can with ease be, as it were, repaired. In justice to Mr. Murray I should add that I omitted all mention of his invention in any former issue, because some principal contractors were to my knowledge intending to make him an offer of a sum of money for it, and under such circumstances I could not think it right to give a description of it. A like feeling induces me to postpone to another occasion details of this clever contrivance; its simplicity is such that a mere outline would put a maker of instruments in possession of means for its construction.

The fillets which have passed between the draw-bench cylinders are cut into lengths of about 18 inches by the shears shown at X, in Fig. 11, and are then sent to the trier, who by means of a hand-press similar to, but more delicate than, that shown at Fig. 7, punches out one or two blanks from each length of 18 inches, and weighs it, or them, against a standard weight, and in accordance with his judgment directs the fillets to be cut by the boys or men at the machines. The trier allows 0·20 grain on the pound of blanks for the loss which afterwards occurs by annealing.[21] If, however, the bars, as previously suggested, were cast uniformly of the thickness of 0·50 inch, this allowance, which is equal to a value of £34 8_s._ 7½_d._ on each million, need not be made; but in fact, as will be seen, even this is not sufficient to cover that loss under present circumstances.

[Footnote 21: See page 48.]

Not only has it become a habit to smile at the draw-bench, but every unfair attempt has been made to get rid of it. Officers were abused because they would not report against it, and the machine itself was submitted to usage never contemplated by the inventor. The then chief coiner, who had formerly seen soap used in calico works in Manchester, insisted on using soap-suds, whereby the beds for the cylinders became rusted, the cylinders destroyed, and the whole machine thrown out of gear, so that 30 per cent. of all the work was rejected: these perverse trials, extending over weeks, appeared to throw discredit on the draw-bench. Having been a calico-printer, that officer endeavoured to engraft on to the processes of coining some of the practices adopted in that business; but had he duly appreciated the principle on which the draw-bench acts, he could not have attempted the use of soap-suds, or, at least, on its complete failure would have assented to its disuse. The very first object of the draw-bench is to produce just so much friction as will cause the lateral displacement of the molecules of the metal then under its operation. Soap, when it adheres to the bullion, permits the fillet to pass without friction, and when it is scraped off by the cylinders the gold becomes so hot from friction that the hand cannot with safety touch it; hence there are alternating parts of the fillet very hot and absolutely cold, and, as a consequence, no two blanks can be obtained of equal weight. Sir John Barton not only made the machine, but determined also that oil was the only fit lubricator for metal made to pass through the cylinders of the draw-bench. Forgetful of the immediate wear on the surface of the metal, others have attempted to replace the cylinders by wedges of steel, so made as that a constant stream of cold water should keep them cool when in operation. This also failed from the formation of rust, while the work produced never equalled that obtained from cylinders. The proper use of the draw-bench is to reduce fillets to an equable thickness in every part, and this can only be done when the trier, after studying the quality of his metal, has determined how much he can remove by once passing through the cylinders; then by keeping up a constant succession of fillets, properly smeared with oil, so that the equable friction always maintains them at the same temperature. Under such circumstances, and with a remedy of 0·24 grain, the rejected should not exceed 2 per cent., and this on the whole day’s work should contain half its weight of light and the other half heavy blanks. This also was a curious instance of want of knowledge on the part of that controlling officer, who for years maintained that if the work were properly conducted _all the rejected_ should be on one side of the remedy.[22] The fillets, notwithstanding the draw-bench, cannot be brought to perfect accuracy, and to meet such variations as arise, a difference is made in two of the cutting-out punches by altering their diameters to such an extent that a blank cut by them from a standard fillet would vary in weight from a blank cut by a standard cutter from the same fillet. One cutting-out punch is so altered that a blank would be 0·125 grain, and the other that a blank would be 0·250 grain heavier. This admits of a fillet otherwise too thin being used; but if the fillet be found to err on the other side, it is passed once more either through the draw-bench, or through the mill at a spring-pinch. The trier, Mr. William Fenton, is a peculiarly steady man, possessing a calm judgment, with considerable energy, and upon him depends the accuracy of the whole process of coining; he has not unfrequently so managed his work that upon 5,000,000 of sovereigns coined, he has been within one sovereign of the calculated value.

[Footnote 22: See page 39.]

The fillets, having been thrown by the trier into the receptacles which indicate the particular cutting-out punches to which they are to be taken, are fetched by a man, who wipes off the oil, and then carries them to the cutting-out room, where the fillets are cut into blanks and scissel. In this place it may farther be noticed that soap-suds cannot be used in the place of oil, because the soap could not be removed without washing,—a practical impossibility,—and would therefore remain, and add indefinitely to the weight of the gold, and thus open the door for peculation. The cutting-out presses used in the Royal Mint are very cumbersome, and when in operation are terribly noisy: it is therefore hoped that at no distant period they may be replaced by some of a far more simple construction; but it is believed that under all circumstances it will be found wise to adhere to the plan of cutting out a single blank at each descent of the punch.[23] For bronze it is well to obtain five or more blanks at each blow, but the limited variation of weight allowed by law on blanks of the precious metals would render this false economy. Fig. 13 represents one of the twelve cutting-out presses, which are all driven by the wheel A, provided with a series of cams on its outer rim; one of these cams, B, is in the act of striking the friction roller C, which is attached to, and forms part of, the lever D. D is fixed to an upright shaft E, which at F is cut with a screw thread working into a female screw fitted into the main shoulder of the press at G. If now the cam B strikes C, and throws it outwards, it causes the shaft E to take a part of a revolution, and in so doing the screw F makes it rise and carry with it the block H, whose tendency to circular motion is prevented by a plug fitting into its groove, and fixed in the guide I. The lower end of H carries the screwed cap J, which supports the cutting-out punch, so that when E rises it carries the cutting-out punch through just the same distance that itself travels upwards. The cutting-out punch is now ready for action, and is released by the continued revolution of the wheel A, as will be seen by the figure; but as it could not fall with sufficient force of itself, assistance is rendered by the pressure of the atmosphere, as will be seen by the following arrangement. The lever D is provided, near its junction at E, with a loop of iron travelling on a screw, so that it may be moved farther from, or nearer to, the centre of action, and thus admit of the increase of power. This loop of iron is represented by K, and is continued by a rod of iron across the upper part of the room and through a hole in the wall to a system of levers L, from which a rod is suspended, the lower end being connected with a piston working in the chamber M. The chamber M is an hermetically-closed vessel secured to a stone firmly fixed in the floor. The piston works in this chamber, and is covered with about two inches of oil, which prevents the access of the atmosphere by leaks to any part beneath the piston. If the piston, therefore, be raised from the base of the chamber, a vacuum is produced in that portion from which the piston is removed, and consequently the atmosphere presses on the surface of the oil, which in its turn presses on the piston, and carries it down (the reverse of the action explained by Mr. James Napier in “European Mints”); in its fall the piston pulls down the cutter, which has been raised; for the same blow which raises the cutter also raises this piston; therefore, when the cutter is raised the workman places the fillet N, from which blanks are to be cut, on the bolster, shown at O, and holds it firmly while the cutter descends and punches out a blank, which falls through the bolster into the drawer P. By the time that the down stroke of the cutting-out punch is complete, the wedge Q has entered a slit in the spring R, and strikes the spring, thus throwing the machine back, and preparing it to start when the cam B shall strike the friction roller C. The point at which Q may strike R is determined by a screw near the left-hand T. The upright shaft E, which is partly hollow, terminates at a flat cogged wheel, and the upper part of F is made to pass into E; while at S is an arrangement which serves to detach or connect these pieces, that the cutter may upon occasion be used by the hand by means of the lever T, as well as to admit of the necessary alterations, as the punches, by regrinding, become shorter. The cutting-out punch, when it rises, carries with it the fillet from which the blank has been punched, until the fillet comes against the guard W, which detaches it.

[Footnote 23: See p. 169.]

The fillets from which the blanks have been punched have the appearance of ribbons perforated with round holes, and are now called _scissel_ (from the Latin _scindo_, to cut). These are thrown into a tray, U, from which they are taken at intervals, and bound up by strips of the same into bundles of 180 ounces—in the case of silver 360 ounces—ready for re-melting. The cutting-out press is set at liberty to start by the workman pressing his foot on a lever in connection with the line and spring indicated by V; and so long as he keeps this lever down, the press is worked continuously, but when he releases it the spring catches the extreme end of D, and motion is arrested. The blanks which accumulate in the box P are collected at frequent intervals and examined, to see that their edges are smooth; if they be ragged, as may happen from the wear or fracture of the edge of either the cutter or bolster, a loss would be entailed in after processes which would cause the coin to be outside the prescribed limit, and to pass at an illegal weight into circulation, as the rough edges would be removed after the weighing of the blanks had been effected. According to the quality of the work—the character of the gold—under operation, the trier tests more or less frequently the variations of weight in a given number of blanks. This process is called POUNDING, and is, next to the _trying_, the most important of his duties; if such an expression can be admitted, he has, by _trying_, fired his shot, and here determines if he has hit the bull’s-eye, all depending on his own unaided judgment. The gauge, Fig. 8, is found of great service in detecting irregularities as to diameter and thickness, which would not be, and are not, detected by weight, for the weight may remain equal, although both diameter and thickness may vary. All these points require considerable care on the part of those whose duty it is to attend to them; for the quality of a coinage is determined in this room: blanks which once leave it cannot be afterwards altered. The subsequent operations, being purely mechanical, would be quite as well performed by automaton machines.

The completing processes form undoubtedly the prettiest and most interesting part of the operation of coining; nevertheless the processes already described constitute its most essential features. The blanks are weighed from this room in drafts of about 720 ounces, and placed in bags; each bag, therefore, contains four _journeys_ of about 180 ounces each. The term _journey_ is said to be derived from an old French word, but circumstances render it probable that this derivation has been applied by others than the original inventor of the word, for it manifestly was not used by the coiner of it to imply a “day’s work.” I cannot find an author who gives a time at which 720 ounces of silver became a journey, while 180 ounces of gold were also called by the same name. It must have taken far longer to coin 720 ounces of shillings or groats than to coin 180 ounces of sovereigns or half-sovereigns; hence the same word could never have been intended to mean “a day’s work.” Be this as it may, it is time that such names gave place to more appropriate and expressive terms. It is to be hoped that 500 ounces will become the standard maximum weight for bags of either of the precious metals; such a system would be the means of reducing the chance of error, it would have an actual meaning, and would be a convenient weight for a man to lift to and from a scale-pan. When such a measure shall be convenient to the officers of the Bank of England, that institution will subserve the interests of the Mint by adopting it.

In a paper recently published by the Commissioners on the International Coinage (at page 228) it is stated that “in the British Mint 15 pounds troy of standard gold are coined into 701 sovereigns nearly (15 lbs. = £700 17_s._ 6_d._).” This statement does not exactly convey the truth, and is calculated to mislead, because such an operation is not, and never has been, conducted in the British Mint, where the invariable rule is to abide rigidly by the law, and to coin 20 pounds troy weight of standard gold into 934·50 sovereigns, as specified in the Mint Indenture, now replaced by the Act of Parliament, 33 Vict., cap. 10. Of these sovereigns so coined, 701 are placed in a bag, and called a _journey_; but by a Mint fiction the journey was considered by the old moneyers, and yet more ancient weigher and teller, 15 pounds troy exact, because the parts of an ounce were difficult of addition; and this was maintained until 1860, when a disputed weight with the Bank of England as to the value of the deliveries corrected that which I had previously pointed out as an error. It is now the custom to consider a journey as consisting of 180·03125 ounces, instead of, as it is, 180·03210 ounces, an error of ·00085, which has a money value of about 6_s._ 7½_d._ on each delivery to the Bank.

WITH PILCHER’S IMPROVEMENTS.]

The bags of blanks should[24] be carried forward to the room in which the weighing of the individual blanks is effected by Mr. Cotton’s automaton weighing machines. Mr. Cotton’s weighing machines form perhaps the most elegant and clever invention of modern times. They effect the process of weighing far more accurately than man can hope to do, and with extraordinary accuracy determine the weight of about twenty-three blanks per minute. Peculiarly admirable as are these machines, their perfection has been greatly increased by improvements suggested by Mr. Richard Pilcher, who has immediate charge of those in the Royal Mint. Mr. Pilcher, whose inventive genius is only equalled by his desire to give to the public the benefit of his inventions, has rendered these automaton balances serviceable to the Mint; whereas, when they left the hand of Mr. William Cotton, they were of great service to the Bank of England alone, for there only two determinations, or in fact one determination is necessary. In that institution it is required to show that the coins issued by it are not below the legal weight for circulation, whereas the Mint must guarantee that coins leave its works neither above nor below the limits fixed by law: hence the necessity for the incorporation of Mr. Pilcher’s improvements with Mr. Cotton’s beautiful invention.

[Footnote 24: See pages 42-44.]

After reading the letter of Mr. James M. Napier in the _Times_ of September 2nd, 1869, I can but express my surprise that that gentleman has not seen fit to acknowledge Mr. Pilcher’s modifications instead of claiming for himself all the credit, when a part only—and that undoubtedly an important one—is his due.

The steel engraving exhibits a view of COTTON’S automaton machine as used in the Royal Mint, where seventeen such machines are employed. For the purpose of illustration, the brass side of the machine has, in imagination, been torn away, as also has the top of the machine. To obtain the highly-finished drawing from which this engraving was made was a matter of no ordinary difficulty, but it was accomplished by the skill and assiduity of Mr. E. S. Gibson, to whom my thanks are due, as well as to Mr. J. W. Lowry, for the pains he has bestowed in executing the engraving.

The whole theory of this balance rests on the fact that the centre of gravity and the centre of action are in one line: either being disturbed, the balance is no longer equal. The machine gains its motion from a shaft fixed to the ceiling of the room. Steam contained in a boiler exists under an ever-varying pressure, arising from the amount of work which it may be necessary for the engine to perform, or from the irregular combustion of the fuel, as well as from other causes. Since it is of the utmost importance that the automaton balance should be made to maintain a uniform pace, Messrs. Napier and Sons found it necessary to drive the shaft which gives it motion by a small atmospheric engine, which is placed in the weighing room. It has been found that a chamber may be kept equably exhausted of air, if the atmosphere be admitted to it by a uniformly weighted valve. Such a chamber—to be described presently—is used in the Mint for other purposes, and Messrs. Napier conducted from this a pipe, by the agency of which the atmospheric engine is worked with a far more even and steady motion than could be obtained by steam; in fact, the exhausted chamber becomes a regulated spring, which softens down the variations in the motion of the steam-engine. The shaft supported by the ceiling conveys its motion to the weighing machine by a line A, which, passing over the friction wheels B, circulates round the stepped wheel C, which runs loose on the shaft communicating with E. The line A is maintained with sufficient rigidity by a weight D, which is suspended at the end of the lever carrying the friction wheels B. The weight D is just sufficient to insure the continuous working of the machine, but is so light as to permit the line A to slip on C in the event of anything going wrong in the works of the balance. When the machine is to be set in motion, a kind of cheek is made—by screwing—to touch the face of the wheel C, and thus, by friction, C gives motion to the wheel E. This is an elegant mode of meeting a chance of accident, for in the event of the weight D proving to be too heavy, any extra force simply disconnects this cheek from the face of C, and so stops the machine. The machine having been set in motion, E, by communication with the wheels F, all of which are driven by it, causes the cam G to push forward the lever H, which, terminating at I, pushes forward the flattened continuation of I indicated by dotted lines, until it moves a blank placed in the collar J, at the bottom of the hopper _h_, on to the scale-pan K, which, for the sake of clearness, is isolated, and will be seen behind the machine and under the extreme end of the hopper. So soon as the blank coin has been placed on the scale-pan K, the cam L lowers a lever _n_, the office of which is to permit the opening of the forceps M, and thus to release the rod, Q, dependent from K upon the knife-edge R. The forceps are closed by the cam L, which raises _n_, and by it compresses an attached spring. The forceps are intended to hold _this_ rod Q while the blank is placed on K, because the friction caused by the placing of the blank would have a tendency to push K from the knife-edge on which it is suspended, and thus blunt its delicate edge. While the forceps are opened the cam N, by its partial revolution, lifts the rod O, which is steadied in its motion, by a pin rising from it, and entering the inverted arch _o_; its lower extremity working into a socket on the table on which the whole frame of the machine stands.

Towards its lower extremity the rod O will be seen to branch out right and left, until each end passes through a kind of step in the rods Q, indicated by P. The office of this rod is to bring the beam, from which the rods Q are dependent, to a dead level, as well as to release both ends of the beam by one action. At the moment that the forceps M have released the right hand rod Q, the cam N, by O, releases both the rods Q, by rising from the steps P, thus permitting the beam to determine the weight of the blank placed on K. A close inspection of the steel engraving will show that the rods Q are suspended from and rest upon the knife-edges R of the beam S, which has a centre knife-edge T, by which the whole mass is supported and poised. The knife-edges are made to find their own planes or resting-places upon curved or hollow pieces of steel, thus securing the smallest point of contact with a certainty of the smallest amount of friction. In ordinary balances the substance to be weighed is placed in a pan, which is on the same level as the pan which contains the counterpoise; but in Mr. Cotton’s balance this condition is of no consequence, so that the counterpoise rests ultimately upon a point which is at the same distance from the centre of action as the point upon which the matter to be weighed rests. The counterpoise U is placed in a kind of cage, and any variation from this standard is at once indicated, even if it reach only to the thousandth part of a grain. By law, the weight of a coin may vary to a certain extent from a standard weight;[25] the variation or latitude allowed is called _remedy_, from the Latin _ad remediam_; and in weighing, this remedy is taken advantage of by a contrivance much simplified by Mr. Pilcher. The weight of a sovereign is 123·274 grains, but it may by law be either 123·474 grains, or it may fall to 123·074[26] grains. Mr. Pilcher therefore reduced the counterpoise to the minimum allowed, thus avoiding the placing of a remedy-wire for the light side; and he then made the remedy-wire _q_ (shown in the first enlarged portion on the left-hand side of the steel engraving), which is placed on the stand W, upon a peculiarly-formed point indicated by V, so heavy that any blank which would not raise it and the counterpoise must be within the remedy on the _heavy_ side. In accordance with this arrangement, the continuation of the rod Q is terminated by a cage at V; so that if a blank be so _light_ as to be unable to raise the counterpoise U until the stirrup comes in contact with the remedy, it is too light to make a legal coin. This fact being determined, the motion of the machine causes the cam X to bring back the rod I (indicated by dotted lines), that it may be ready when required to push forward another blank, and the forceps M to grasp the rod Q, while the cam Y permits the falling of the rod Z, which is nearly counterpoised by the ball _m_ (the precise length of the rod being regulated by the screw _j_), until its finger _a_ rests upon the indicator _b_. The depth to which _a_ shall fall is fixed by the step _l_ (shown by Q in the second enlarged portion of the steel engraving). This is, of course, determined by the forceps, securing Q at the position indicated by the weight of the blank. The indicating finger _b_ having come to rest, the continued motion of the machine causes the cam _c_ to permit the shoot _d_ to fall until one of its steps _e_ comes into contact with the indicating finger, when the lower part of the shoot must be exactly over, and form part of, one of the tubes _k_, which terminate in boxes labelled respectively “heavy,” “light,” “medium.” The shoot having taken its position, the continued motion of the machine causes the cam G to induce the placing of another blank on the scale-pan K, and this blank, by advancing, pushes off the one just weighed, which, falling into and through the shoot, passes to the compartment reserved for it. Suppose the newly-placed blank to be too heavy for forming a legal coin, the same operation goes on, but it now lifts not only the counterpoise, but also causes the stirrup at V to lift the remedy-weight _q_. This is a most delicate operation, for if a blow, however light, be given, it would cause unsteadiness in the beam. Mr. Pilcher therefore determined to make the carriage W, which supports the remedy-wire _q_, stand upon micrometer screws, by which the remedy-wire is made just to touch the stirrup, without pressure, while it also rests upon the most minute points, formed by cutting away every part of V which is not actually required—in fact, shelving it out. The scale-pan K is protected from draught by the lantern _f_, while the blanks are directed into the collar J by the guard _g_, as they slide down the hopper _h_, which at its centre is supported by an upright, _i_. The blocks _p_ are the supports which hold all the machinery to the roof of the machine.

[Footnote 25: See pages 71-73.]

[Footnote 26: See pages 73, 123, 124.]

Some new machines have recently been supplied to the Mint by Mr. James Napier, but it is not certain that these are cheaper than the old ones. That they are lower in price may be admitted, and they are certainly more convenient in use, from the fact that the wheels shown at F are placed at the back. It is, however, to be regretted that Mr. Napier did not introduce into these new machines the recent inventions of Mr. William Bradshaw, which are supremely simple, and, now that they are effected, one cannot but wonder that so many minds having been engaged on these machines, improvements such as these have not earlier seen the light. To Mr. Bradshaw, particularly, great credit is due, for he was obliged to overcome, not only innate difficulties, but difficulties of position, and these latter were of no mean kind. It is to the credit of the Mint authorities that they finally adopted these improvements, and ordered the necessary alterations to be made in _all_ the machines.

Mr. Bradshaw’s improvements enable the automaton balances to weigh 30 per cent. more coins in the same time; yet they permit each coin to occupy a longer space of time in being weighed. This would appear to be a mechanical contradiction, but if reference be made to the plate it will be seen that the cam G pushes forward the lever H, which ultimately, by the slide, pushes the blanks on to the scale-pan K. By altering the shape of the cam G, Mr. Bradshaw causes it to do its work more rapidly, and thus leaves the piece on K longer than before; but that this time may not be lost, he alters also the shapes of the cam L and of the cam N, so that the forceps M are opened, and the beam is released more rapidly: thus the balance would be longer in action; but to utilise the time ready to be saved, he alters also the driving pulley E, causing the machine to make 30 per cent. more determinations per minute, and that this may be effected with greater certainty he reduced the depth of the step, shown at _e_, to just one-half, so that the beam has to travel only half the distance it formerly travelled to determine the position of the light, heavy, or medium piece. He next proceeded to alter the rod O, because he observed that it received a tilting motion arising from its being lifted by a shoulder, as shown in the plate. To overcome this defect he made the rod straight up to a certain point, where he divided it into a kind of loop which passed over the cam N, which, as it revolves, lifts this rod perpendicularly. He still found that the cam N had a tendency to push this rod against its bearings, especially at _o_, so he placed a spring of brass between the top of its loop and the cam N, and secured at one end to _p_, and by this contrivance made the cam to lift the brass, and that in its turn to raise the rod O. There was yet another difficulty, caused by an occasional stoppage of the action of the spring which softens the descent of the bearing of the rod O into its lower socket; this he removed by cutting a hole in the side of the socket, so that it can be seen at once if the spring be in action. I am not one who approves his suggestions as to the remedy-wires. These may be the means of saving time, but they are wrong in principle, and I do not describe them.

Great inconvenience arose from the collection of dust, spangles of bullion, and other foreign matter on parts of the balance. This Mr. Bradshaw overcame by two simple contrivances; first, he pierced the bottoms of the grooved trays, so that these substances might in a great measure fall through while the blanks were being arranged in rouleaux, thus separating the largest pieces, which, falling down the shoot, would stop its action; and, secondly, he placed a glass shelf midway between the table and the beam, that is, beneath the hopper _h_, where it terminates at J, and above the beam S, where it is seen near the forceps M, thus protecting the beam and forceps. These may appear to be trifling alterations,—they are nevertheless to Cotton’s balance what the compound metal balance-wheel is to a watch. Mr. Pilcher was granted the _magnificent_ sum of £40 for his invention of the file (to be described), but it is hoped that Mr. Bradshaw will be rewarded with a far more open-handed generosity; for if, by judicious liberality, encouragements are offered to those in the Civil Service to give to the country the benefit of their inventions, we may still hope that even our Government institutions will bear comparison with ordinary commercial manufactories as regards the development of inventive genius. Nor is this a small matter, for all the working improvements in the Cotton’s balance have been made by those whose duty it is to attend to their working; yet I am not aware that any acknowledgment, either direct or indirect, has been made to the officers concerned. It is said that their salaries cover all their time and energy. This may be true, but such a policy is not calculated to result in many great steps towards perfecting either machines or processes.

It is well to state that the beam in Mr. Cotton’s balance is 8·90 inches in length, and that its weight is 288·41 troy grains.

Those blanks which are neither too light nor too heavy are called _medium_, and are weighed and put into bags for future issue as coins. The _light_ are reserved for the melting-pot. The _heavy_ blanks should be reduced by means of a peculiar kind of file to the weight of medium blanks, and thus saved from being melted, so avoiding further loss to the Mint. This file was invented by Mr. Pilcher, who, being the officer of this room, considers his duty to be neglected if there be any improvement capable of being made, but which is left undone; he never tires till the invention is complete and the machine made. Mr. Albert Barre, the distinguished engraver to the Paris Mint, declares this file to have surmounted all the difficulties he has met with in this part of the process. In his own words, “it leaves the face of the blank untouched, and free to develop the work of the engraver, which no other file does, or can effect, because any metal which is _ploughed_ out from the face of a blank, leaves a hole which is not filled up in coining.”

The opinions which I have here expressed have so far prevailed on two of the travellers to European Mints, as to induce them to glance, though rather shyly, at the necessity for reducing heavy blanks; but Mr. Napier writes a passage which I quote, as it demonstrates that he, who is admittedly one of the most successfully ingenious men of the age, has thought over and studied the words I wrote at page 60 of the last edition—he took that book in his hand to the Mint on the day after its publication—with that attention to which he thought they were entitled. I beg the reader to ponder over Mr. Napier’s words, they are most important; but I hope those who will be called upon to vote the necessary money will also read my remarks on this extract from Mr. Napier’s report on European Mints. He says at page 44:—

“_Treatment of Too-heavy Blanks._—Notwithstanding the
employment of the best mechanical appliances for rolling
the bars, adjusting the fillets to gauge, and cutting
out the blanks, and the most intelligent and painstaking
workmen to carry on the operations, still, owing to
unavoidable imperfections in the means, the blanks, when
cut from the fillets, will not be found equal in weight,
nor, indeed, so nearly equal that they can be recognised as
of equal value, and passed on to be manufactured into coins
destined to be put into circulation, and to represent one
value. The irregularities will necessarily be more or less,
according to the care and ability of the workmen, and the
condition of the machinery; but under the most favourable
circumstances only a certain proportion of the blanks
will be found to come within the limits which it has been
considered desirable to set down to restrict the quantity
of error.

“This being so, the following questions present themselves:
Are the too-heavy and too-light blanks to be returned to
the crucible and remelted, or to be passed on and detected
only in the finished coin, and then sent to the crucible?
Or are too-light blanks to be avoided altogether, and
all the blanks to be made either of sufficient weight or
too heavy? and in such case are the too-heavy blanks to
be submitted to some process for reducing their weight
to within the legal limit? Or is a more exact means to
be preferred, by which they will be equalised to that
perfection which cannot practically be questioned, and by
which they will become, for all purposes, one and the same
weight?

“The facts collected are, that at nearly all the European
Mints the reduction of too-heavy blanks, both of silver
and gold, is practised, to avoid the loss attendant upon
their return to the crucible, and that the endeavour is
to make all the blanks either standard weight or heavier,
so as to admit of reduction, to err, indeed, on the heavy
side, even to the extent of necessitating the reduction
of all the blanks. So great is the importance generally
attached to this department, that it is calculated that, in
some instances, nearly as many hands are employed in the
service of it, including the weighing, as in all the other
working departments combined. In Berlin, where particular
care is devoted to the weight of the coins, between 200 and
300 men are employed in times of pressure in the weighing
and equalising of the blanks, which operations are in this
instance performed by the workman with a hand shaving
apparatus, fixed to the table at which he sits, and a pair
of scales also placed near to him. The work done by one man
is revised by a second, and the file is used for giving the
finishing touch, so that the blanks are brought to great
perfection in weight. But although the extent of the means
shows the great importance attached to the results in the
establishments visited, and the large expenditure which, at
least in the opinion of the directors of these Mints, may
be permitted with profit in this department, the serious
consideration of the employment of so many hands would
militate against the carrying out of the system in the New
Mint. It may be satisfactory, therefore, to know that,
in case the desirability of an exact coinage should be
entertained, means for assuring it are at hand without the
employment of manual labour for the purpose. The subject
has, indeed, for many years occupied attention, and,
after much labour and expense, the difficulties have been
overcome, and a machine has been constructed to the order
of the Government of India which fulfils all the required
conditions for equalising the coinage to that perfection
that no appreciable difference need exist between the
standard weight and the coin blank which has passed through
the machine. This machine differs essentially from those
employed at the Mints visited, and which, it has been
explained, only take a fixed quantity off each blank
presented to the cutting tool, without reference to the
weight of the blank, the operation being repeated or not,
according to the result; or, in other words, no matter what
be the weight of the blank, whether nearly light enough, or
much too heavy, the cutting tool of the machine treats all
in the same manner.

“The equalising machine referred to, on the contrary, not
only takes from the too-heavy blanks, each in succession,
a quantity of their surplus weight, but it ascertains how
much it is necessary to take off each blank to reduce it
to the standard weight; and it deducts that amount only;
so, although the blanks which are supplied to the hopper,
or reservoir of the machine, enter the machine of unknown
weight, they are equalised by it in once passing through,
and are delivered into a receptacle for the finished work,
all of one weight, the standard, or so near to it that good
ordinary scales, such as are used for weighing blanks and
coins, will not detect a difference.

“Means can therefore be provided for the purpose, should it
be decided to reduce the blanks to equal weight, or only
to within the pale of accuracy instituted by Parliament,
the basis of which legislation must be taken to have been
the then practicable approach to perfection; for it is
to be presumed that, with a sufficient assurance that
accuracy akin to perfection was attainable ALONG WITH
ECONOMY, the wisdom of Parliament would have enacted
accordingly.

“The first outlay for self-acting coin blank equalising
machinery WOULD NECESSARILY BE LARGE, but it
is believed at the same time that the saving would be
considerable, especially upon gold.

“The question of the amount of economy would have to be
more fully gone into, and the expense of the machinery
accurately estimated. Extensive and continuous experiments
with the machine have also STILL TO BE MADE TO ACQUIRE
A KNOWLEDGE OF ITS USE, and to ascertain, after a
_lengthened_ probation, whether any modifications in
the details are advisable: the limited experiments already
made leave no doubt, however, of the successful result.