Perkin's patent of 1819 No 4400

Specification of Patent of Jacob Perkins, and two advertisements of Messrs. Perkins, Fairman & Heath, on the formation of the firm in December, 1819.

(I)

A.D. 1819. No. 4400.

Engine lathe for engraving surfaces, printing and coining presses, etc.

Perkins' Specification.

To all to whom these presents shall come, I, Jacob Perkins, late of Philadelphia, in the United States of America, but now residing at Austin Friars, in the City of London, engineer, send greeting.

Whereas His Most Excellent Majesty, King George the Third, did by His Letters Patent bearing date at Westminster, the eleventh day of October, in the fifty-ninth year of his reign, give and grant unto me the said Jacob Perkins His especial license, full power, sole privilege and authority, that I, the said Jacob Perkins, should and lawfully might make use, exercise, and vend, the invention, partly communicated to me, by a certain foreigner when residing in America, and partly of my own invention, of "Certain machinery and implements applicable to ornamental turning and engraving, and to the transferring of engraved or other work from the surface of one piece of metal to another piece of metal, and to the forming of metallic dies and matrices ; and also improvements in the construction and method of using plates and presses, for printing Bank Notes and other papers,

whereby the producing and combining various species of work is effected upon the same plates and surfaces, the difficulty of imitation increased, and the process of printing facilitated; and also an improved method of making and using dies and presses for coining money, stamping medals, and other useful purposes."

In drawing, No.i, is represented an engine lathe for engraving oval or circular geometrical figures upon metal or other surfaces, whether flat, convex, or concave, ....[the peculiarity in which consists in producing a lateral motion of the mandrell, by means of the eccentric cylinder or other shaped body upon a separate axis, and of varying the number of lateral motions of the mandrell during one revolution thereof, by means of wheels of various diameters.]

2. In drawing No. 2 is represented an engine lathe for engraving certain figures, upon the peripherics of metal or other cylinders [the novelty of which consists in producing the longitudinal motion of the mandrell by a different modification of the same expedient.]

In drawing No. 3, Fig. i, represents the horizontal vibrating lever press viewed in front; Fig. 2, an end section of the same [On the upper surface of an adjustable bed is placed the copper or steel plate to receive the impression from the circular die or roller.] The die or roller j consists of a hollow steel cylinder, fitted upon a steel axis, which is formed into two cylindrical necks on each side of the roller... Each end of the axis of the die or roller j is made square, on which squares fit the square gaps made in the ends of the die lever or double spanner 0, and by means of which the die or roller can be turned backwards, and forwards upon the surface of the steel or copper plate w lying upon the bed g, as aforesaid...

In drawing No. 4, is shewn an improved steel or copper plate or block printing press, Fig. i being a front view of it, and Fig. 2, an end view.

The principal improvements consist in a new method of heating the plate, or block, in the use of a tympan, for the purpose of saving the expense of making the plates or blocks any larger than is necessary, to receive the engraving as well as to save ink, and also time and labour in cleaning the plates or blocks...

In drawing No.5 is represented a cylindrical steel or copper plate printing press....

[the improvements claimed in this consist in affixing a number of engraved circular plates to the surface of a cylinder, so that the operation of inking the plates, wiping, and cleaning, and printing from the said plates shall be simultaneous and continuous.]

I In drawing No. 6 is represented parts of a circular coining press,... In order to decarbonate the surfaces of cast-steel plates, cylinders, or dies by which they are rendered much softer and fit for transferring or engraving designs thereon, I find that pure iron filings, divested of all foreign or extraneous matters produce the softest decarbonated surface, and therefore I use iron filings, as pure and as free from rust as I can obtain them. I also carefully exclude all carbonaceous matter, and any substance from which carbon can be obtained. The stratum of decarbonated steel should not be too thick for transferring fine and delicate engravings; for instance, not more than three times the depth of the engraving. The surface of the steel may be decarbonated to any required thickness. To decarbonate it to a proper thickness for fine engravings, I expose it for four hours to a white heat, enclosed in a cast-iron box, with a well closed lid. The sides of the cast-iron box I make at least three-quarters of an inch in thickness, and at least a thickness of half-an-inch of pure iron filings, should cover or surround the cast steel surface to be decarbonated. The box should be suffered to cool very slowly, which may be effected by shutting off all access of air to the furnace, and covering it with a layer six or eight inches in thickness of fine cinders. Each side of the steel plate, cylinder, or die, must be equally decarbonated, to prevent it from springing or warping in hardening. I also find it much the safest way to heat the plates, cylinders, or dies in a vertical position. I make use of good cast-steel in preference to any other sort of steel, for the purpose of making plates, cylinders, circular or other dies, and more especially when such plates, cylinders, or dies are intended to be decarbonated. For the reason given above, the steel is decarbonated solely for the purpose of rendering it sufficiently soft for receiving any impression intended to be made thereon. It is, therefore, necessary that after any piece of steel, whether in the shape of an engraved plate, or a cylinder, or a die, with engraved or other figures upon its surface, should be again carbonated or reconverted into steel capable of being hardened.

In order, therefore, to effect this carbonisation or reconversion into steel, I employ the following process: I take a suitable quantity of leather and convert it into charcoal by the well-known method of exposing it to a red heat in an iron retort for a sufficient length of time, or until all the evaporable matter is driven off from the leather. Having thus prepared the charcoal, I reduce it to a very fine powder, I then take a box, which I prefer having made of cast-iron, of sufficient dimensions to receive the plate, cylinder, or die which I wish to have reconverted into steel, so as that the intermediate space between the sides of the said box and the plate, cylinder, or die, may be about one inch. I fill the said box with the powdered charcoal, and having covered it with a well-fitted lid, I place the box in a furnace similar to those used for melting brass; I increase the heat gradually until the box is somewhat above a red heat, and suffer it to remain in that state till all the evaporable matter is driven off from the charcoal. I then remove the lid from the box, and immerse the plate, cylinder, or die, in the powdered charcoal, taking care to place it as nearly in the middle as possible, so that it should be surrounded on all sides by a stratum of the powder of nearly an uniform thickness. I replace the lid, and suffer the box with the plate, cyhnder, or die, to remain in the degree of heat before described for from three to five hours, according to the thickness of the plate, cylinder, or die, so exposed. Three hours are sufficient for a plate of half-an-inch in thickness, and five hours when the steel is one inch and a half in thickness. After the plate, cylinder, or die, has been thus exposed to the fire for a sufficient length of time, I take it out from the box and immediately plunge it into cold water. It is important here to observe, that I find the plates, or other pieces of steel, when plunged into cold water, are least liable to be warped or bent when they are held in a vertical position or made to enter the water in the direction of their length. If a piece of steel, heated to a proper degree for hardening, be plunged into water, and suffered to remain there until it becomes cold, it is found by experience to be very liable to crack or break, and in many cases it would be found too hard for the operations it was intended to perform. If the steel cracks or breaks it is spoiled; and in order to render it fit for use, should it happen not to be broken in the hardening, it is the common practice to again heat the steel in order to reduce or lower its temper, as it is technically called. The degree of heat to which the steel is now exposed determines the future degree of hardness or the temper, and this is indicated by a change of colour upon the surface of the steel; during this heating a succession of shades is produced, from a very pale straw colour to a deep blue. I have found, however, by long experience that if on plunging the heated steel into cold water, and suffering it to remain there no longer than is sufficient for lowering the temperature of the steel to the same degree as that to which a hard piece of steel must have been raised in order to temper it in the common way, that it not only produces the same degree of hardness in the steel, but what is of much more importance, almost entirely does away the risk or liability of its cracking or breaking.

I believe it to be impossible to communicate by words, or to describe the criterion by which, after long experience, I judge or determine when the steel has arrived at the proper degree of temperature after being plunged into cold water, and I believe that it can only be learnt by actual observation, as I am guided entirely by the kind of hissing or singing noise which the heated steel produces in the water whilst cooling. From the moment of its being first plunged into the water a varying sound will be observed, and it is at a certain period before the noise ceases that I find the effect to be produced, and the only directions I can give by which the experimentalist can be benefitted is as follows, namely, to take a piece of steel which has already been hardened by remaining in the water till cold, and by the common method of again heating it, to let it be brought to the colour which would indicate the desired temper of the steel plate to be hardened by my process, and so soon as he discovers the colour to be that of pale yellow or straw colour, to dip the steel into water and attend carefully to the hissing, or as some call it, the singing noise, which it occasions. He will then be better able, and with fewer experiments, to judge of the precise time at which it should be taken out. I do not mean it to be understood that he temper indicated by a straw colour is that to which the steel plate, cylinder, or die should be reduced, because it would then be found too hard, but merely that the temperature which would produce that colour is that by which the peculiar sound would be occasioned when the steel should be withdrawn from the water for the first time. Immediately on withdrawing it from the water the steel plate, cylinder, or die, must be laid upon or held over a fire, and heated uniformly until its temperature is raised to that degree at which tallow would be decomposed, or, in other words, until smoke is perceived to arise from the surface of the steel plate, cylinder, or die, after having been rubbed with tallow. The steel plate, cylinder, or die, must then be again plunged into water, and kept there until the sound becomes somewhat weaker than before; it is then to be taken out and heated a second time to the same degree, and by the same rule of smoking tallow as before, and the third time plunged, into water till the sound becomes again weaker than the last; expose it a third time to the fire as before, and for the last time return it into the water and cool it. After it is cooled, clean the surface of the steel plate, cylinder, or die, and by heating it over the fire the temper must be reduced by bringing on a brown or such other lighter or darker shade of colour as may best suit the quality of the steel, or the purpose to which it is to be applied … In witness whereof, I, the said Jacob Perkins (party hereto), have hereunto set my hand and seal, this tenth day of April, one thousand eight hundred and twenty.

(Signed)

Jacob Perkins.

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