This Mill produces a double power, merely because it uses two pair of sweeps or sails, both of which (though turning opposite ways) concur in giving the same motion to the vertical shaft of the mill. A B fig. 5, (Plate 38) is the shaft in question. It has on it two bevil wheels or pinions o, b; bearing the same proportion to their respective wheels: one of which (o) works in the wheel C, fixed to the outer shaft a c, and the other (b) in the second wheel D, which takes it’s motion from the inner shaft E D. This latter, then, is turned by the front sweeps F G; which revolve, as usual, “against the sun,” while the other sweeps H I, are braced round the large shaft a c, and turn with the sun—being sloped and clothed for that purpose. Now, lest any doubt should arise, whether these two sets of sails would not injure each other’s motion—I would remark, that one principal effect of the front sail on the wind would only be to turn it aside, and thus make it the more fit to turn the other sails, which require to go the other way; and which, therefore, will rather be favoured than otherwise, by the aforesaid effect on the direction of the airy current. It may be useful to observe, that the two sets of arms can be put, circularly, into any given position, by means of the wheels C D, and will retain that position if the proportions of the wheels to the pinions o b, are the same for each pair—a result which it is easy to insure.

I shall dwell no longer on this subject, convinced as I am that nobody will question the propriety of enlarging the scope of these operations. It is a subject I especially recommend to our Batavian neighbours—the more, as, without presuming to dictate on a subject they may think I have not experience enough to judge of—I have only a hint to give to their Moolen Maakers, to insure their attention to a subject so intimately connected with the welfare of their never-forgotten Vaderland.

OF
A WATCH ENGINE,
To extinguish incipient Fires.

It is well known, that many ruinous fires have originated so slowly, that they might have been put out in a minute, had a little water been at hand—especially with the power of throwing it to a short distance. This fact makes it more desirable than it would at first appear, to have small vessels full of water, furnished, in themselves, with the power of forming a jet, without a moment’s delay! and this is the purpose of the Watch Engine, represented in fig. 6 of Plate 39.

In that figure, A B is a cylindrical vessel, with spherical ends, made strong enough to bear (without danger) a pressure of several atmospheres: and into which is introduced, by a condenser, (which might be the very system C p r) a quantity of water sufficient to occasion the aforesaid pressure. The valve C being water-tight, retains entirely this water; and the Machine is placed on it’s three feet, in a corner of the apartment it is wished to secure. It is seen in the figure, that the valve-pipe C p, opens into the ejection pipe p q, while the valve stem p passes through a collar of leather, and comes in contact with the lever p R while in it’s present position. If, now, any part of the house or apartment should be found to be on fire, this Instrument can be carried there instantaneously, by the pipe p q, as a handle; and the jet be levelled at the point desired: when, by taking the lever p R in his hand, with the pipe p q, the bearer will open the valve C, and thus have an immediate supply of water, in a state of impulse sufficient to quell a fire that might else have become so violent as to mock every attempt to extinguish it! This, then, is the object of the present simple tribute to public safety.

OF
A MACHINE
For Engraving the Cylinders of Calico Printers by Power.

The principle of this Machine is as follows: When two equal toothed wheels a b (see Plate 39, fig. 1,) geer together, a given tooth of either wheel visits a given tooth of the other, once every revolution: and will continue to do so as long as the wheels continue to revolve. But, when the wheels are unequal, as A B fig. 2, then different teeth in one wheel, visit the same tooth in the other, until, after a certain number of turns, the revolutions of both wheels have a common divisor. My System of equable Geering (see Part 2d. of this Work,) justified me in applying this principle to Engraving; and is the chief foundation of the Machine now to be described: for this System, as we have seen, communicates the very same kind of motion that two touching cylindrical surfaces would impart to each other by mere contact. The punch, therefore, will not scrape the cylinder, when brought into the desired places of contact by the aforesaid process. Let us suppose then, (fig. 2) that the wheels A B, are to each other in diameter and teeth, as the numbers 2 to 3; and that a given tooth in the wheel A, (which we have pointed out by a dot) now touches a certain spot on the wheel B, marked by a dot like the former. When, now, this spot on the wheel B has made one revolution, the wheel A will have made ³⁄₂, or 1¹⁄₂ revolution: and the tooth first mentioned, will be found diametrically opposite to the place where it touched the spot first adverted to. And if, further, we give the wheel B another turn, the wheel A will again have made 1¹⁄₂ turn; and the tooth first mentioned will again visit the spot with which it coincided at the beginning.

which numbers are thus in the inverse ratio of the number of teeth in the wheels respectively.

Referring again to fig. 3, there we see a cylinder to be engraven, (M) and a porte-outil (or tool-bearer) N, connected by the wheels A B; whose teeth are singly inclined, like those that were considered in Part 2d. It can hardly ever occur, that the circumference of a cylinder can require to be divided into two parts only: but most often into a greater number, as 9, 11, &c. and it so happens, (from these initial diameters 2 and 3) that we must take uneven numbers for our basis, in order to reduce the System to any thing like regularity. And, this admitted, the theory of this division will be as follows:

Let the chosen (uneven) number of figures required round the cylinder be called m: then must the number of teeth in the small wheel A, be likewise m: when the number in the wheel B, will come out uniformly m + (m ± 1)/2; in which formula every case of practice is included. For suppose, any uneven number to be required, say 11: Then will the cylinder-wheel A, have 11 teeth; and that of the porte-outil (B) 11 + ¹²⁄₂ = 17, or 11 + ¹⁰⁄₂ = 16: either of which numbers, working with the 11 teeth of the cylinder-wheel A, will divide the latter into 11 parts, as was before stated.

It must, however, be observed, that, as expressing a set of teeth actually working, these numbers are fictitious; because the teeth would be too coarse to work well. The numbers thus found, must, therefore, be multiplied by 2, 3, or more, so as to bring the teeth to a reasonable size, say ¹⁄₈ of an inch thick, according to circumstances.

As another example, take the following: suppose it were required to engrave a cylinder of 4 inches diameter—or 12.56 in circumference, and to put twenty-five figures round it, giving very nearly half an inch for each figure. Then the cylinder wheel (A) must have 25 teeth; and the porte-outil wheel 25 + ²⁶⁄₂ = 38: or, doubling both numbers to give the teeth a proper strength, the cylinder-wheel would have 50 teeth, and the porte-outil wheel 76.

To proceed now, in stating the principles of this Machine, it is evident (in this System of geering) that the diameters of the wheels must be in exact proportion with the number of their teeth, taken at the pitch lines; and that these pitch lines must be of the same diameters, respectively, as the cylinder to be engraven, and the porte-outil taken at the surface of the punch: which is saying, in other words, that the length of the punch must be regulated after the diameter of the porte-outil wheel has been determined from it’s number of teeth, compared with those of the cylinder-wheel. But we shall return to this topic after having described more fully the principal parts of the Machine.

In fig. 5, (which is a kind of transparent view of one end of the Machine), A B C is one of the stands or legs on which it rests; a b is a section of the frame or bench, which supports the headstock C D, one of which is bolted down at each end of the frame, (see also C D in fig. 3.) This figure shews the transverse form of the headstock, with the centre (c) of the porte-outil; and e d are the two wedges that go through the headstock to support the step of the cylinder, of which the mandrel appears at f. This mandrel-centre is also covered with a second step, over f, by which it is kept down by means of a regulating screw A, (fig. 3) which finally determines the degree of nearness of the cylinder to the porte-outil, and thus the depth of the engraving:—that is to say, this regulating screw influences this depth as far as the wedges (e d) permit: for by the screw d, these wedges slide on each other so as to raise or let fall the steps f, by small degrees; the position thus given being confirmed by the said regulating screw. It is needless to say that this operation takes place at both ends of the Machine, (C and D) and thus places the surface of the cylinder in a line exactly parallel to the slide n q of the porte-outil.

In fig. 3, all the parts thus adverted to, are given in a front view—where we may observe, that the rope marked by dots at R, is a loaded friction-drag, used to prevent the porte-outil from over-running the cylinder, when the punch is just emerging from between them.

The same figure 3, shews also the position of the frog x, in the triangular slide of the porte-outil; the latter, as well as the cylinder, borne by the headstocks C D. Moreover, the rack w, which gives the end-motion to the punch, is here shewn, as going through the frog, and connected with it in one direction by the catch o: and at n, there is a spring, formed like a horse-shoe, the use of which is to push the frog, by the catch o, to the right, whenever the rack is suffered to go that way, by the mechanism hereafter to be described.

The frog, then, (so called because it seems to leap when the Machine works) must now be adverted to: it consists of an under mass, formed prismatically to fit exactly the slide n q, cut out of the porte-outil N. This mass is capped by a thickness of steel, which completes the passage for the rack n w, and offers, besides, a compartment for the punch-clams o, and another (x) for a wooden or steel bridge, being a portion of a cylinder, so formed, as to support the engraved cylinder after the stress of the impression is passed, and thus to equalize the depth of the engraving. The compartment for the punch-clams at o, is terminated to the right hand by an obtuse angle near x, which serves as a centre, when, by proper fixing screws in the rim near o, it is found necessary to place the punch a little awry. The other properties of this frog will easily be supposed by my mechanical readers.

We come, then, to it’s motion in the slide. p r shews a wheel, running loosely on the axis of the porte-outil; and having fixed to it a concentric rim r, with three or four waves in it’s circumference. Further, above s, is seen a lever, turning on a pin in the stud s, and pressing against the right-hand end of the rack w, when driven to the left by the waves p r, &c. This rack is cut into ratchet teeth as at w, in which enters the catch o, as impelled by a proper spring acting on it, (but not seen in the figure.) As long then, as the waved wheel p r can turn, with the porte-outil N, this last described mechanism does nothing: but when p r is stopped, it begins to work usefully; for the lever s then rides on the waves p r, and presses the rack w against the spring n, so that the catch o, takes into some new tooth; by which means, when the spring n unbends (by the sinking of the lever s into any wave p) the frog is itself carried toward the right hand—which is the effect intended. But, in fine, how is this wheel p r stopped and set agoing a propos? Fig. 5 will shew this, with the aid of a little imagination—since our fig. 5 is a kind of transparency rather than a regular view. The wheel m, is a crown wheel, near which the wheel p r (fig. 3) turns, having a spiral g on it’s hither surface, which runs between the teeth of the wheel m and turns it one tooth, in each of it’s own revolutions: But when, after a given number of these turns, the end of the spiral g meets with a large tooth on m, it lodges on it, and stops the motion of the wheel p, and then the aforesaid waves r perform the task of driving the rack w backward; after which the spring n changes the place of the frog, so as to make another line of impressions round the cylinder. It remains then, only to be explained, how this stoppage is itself stopped; which is thus: to the porte-outil is fastened, near g, a small arm, which turns with it, and which in fig. 5 the dot t represents. This arm, therefore, drives back the beak t, (connected with the spring v) at every revolution of the porte-outil, thereby working the small catch that hangs to that beak. This catch, therefore, slides on the edge of the crown wheel m, but produces no effect, until it finds there, one small notch, so placed as to be acted on by the catch when this disengagement is wanted—and, then, this motion jogs forward the crown wheel m just enough to take the large tooth out of the way—when the spiral g begins to move through the common teeth of m, and thus ceases to act on the rack till the large tooth again comes to stop the wheel p, and recommence the rack’s motions. And thus is the place of action of the punch changed after any number of it’s contacts with the cylinder—that number being doubled or trebled—or more—when necessary, by increasing accordingly the number of common teeth in the crown wheel m, before a large tooth occurs.

A few practical remarks on this mode of engraving may here be added with advantage. Theoretically speaking, the punch should form a portion of a cylinder, of equal radius with the porte-outil wheel, taken at it’s pitch line. But through the relative weakness of some mandrels, a certain spring takes place, which requires the punches to be more curved than that wheel, and even considerably so. This also depends on the size of the punch, and the fullness of the pattern. In a word, it depends likewise on the method of employing the Machine—whether with few passages, and considerable pressure, or with light pressure, and many swift passages:—The latter System is in my opinion much the best; since it brings the practice nearer to the theory of this Machine. If, indeed, the cylinders and mandrels of Calico Printers, had been originally made thicker, and thus strong enough to bear the pressure without sensible deflexion, this would have been, from the first, a perfect process: and the nearer these objects are brought to this state of inflexibility, the nearer will it’s effects approach to perfection; for in all other respects it works with admirable precision.

I may just add, that the facility with which the revolutions of this Machine are counted, has induced some persons to dispense with the rack movement: but for small patterns with numerous impressions, it is doubtless better to use it—especially when employing the rapid and light pressures just alluded to; and these will become additionally interesting when the punches themselves acquire a more exact form—which is the object of the third Punch Machine, still remaining to be described.

It is not superfluous to add, that this Engraving Machine is dangerous to the persons employed—and should therefore be guarded behind, by a fence-bar, to prevent the hands or clothes from being drawn in.

OF
A HORIZONTAL WATER WHEEL,
Probably the best of the impulsive kind.

In this title, I have repeated that given in the prospectus: nor do I think I have assumed too much in so doing. It will be seen in the course of this description, on what I found my opinion; which indeed, was substantiated by the fact as soon as formed: the execution having speedily followed the invention. The Machine, in it’s different parts, is represented in figs. 1, 2, 3, and 4 of Plate 40. Fig. 1 is a plan of the floor, on which the upper water flows, to it’s whole depth, when the flood gates are opened: this floor being close over the wheel, as seen in fig. 4, at c d. Further, a b, in both figures, is a circular slit of the whole diameter, through which the water rushes at once on all the floats of the wheel; whose axis goes up into the building through a kind of barrel, that prevents the water from escaping in any other part than the aforesaid circular aperture. The wheel itself is represented at e f, fig. 2; and fig. 4 is an elevation of it, with it’s shaft, and a few of the floats, to shew the manner of their receiving the stroke of the water. A section of the ring-formed slit is also given at a b, with two floats receiving the flowing water: and in that elevation is also shewn two of the swan-necks by which the central part of the floor is supported on the framing, without stopping the watercourse.

Finally, the slit or aperture a b, figs. 1 and 4, is fitted with a set of cast iron curves, of which six are shewn in the Plate, between c and d, and whose use is to turn aside the falling water to any desired inclination; these instruments being moved at will by a proper chain of bars, reaching from one to the other, and connected with eight or more levers at proper intervals on the floor of the water chamber.

Thus then, it appears that this Machine has two or three very important properties: 1st. all the water escapes in the same direction, (relatively to the motion of these wheels) and that direction concurs with that in which the wheel is made to turn. 2d. Every one of those fluid prisms into which the stream is divided, is urged with the same velocity, because impelled by the same head of water. 3d. The velocity of these jets is the greatest possible, because the water is carried as low as possible before it is emitted; and falls as little as possible after it has struck the wheel. 4th. In fine, the inclination of the floats may be made most perfect; and their form, being that of a boat slightly curved, is among the best forms possible for receiving the utmost impulse from flowing water.

Although by these means much is done in favour of the impulsive system, it is allowed, that, in general, a wheel acting by impulse, is less effective than a bucket-wheel acting by the weight of the water. But the higher the fall is made, the more similar these effects become. Hence, a very high fall may be made to produce, by impulse, an effect equal to that of the bucket-wheel. To meet, therefore, such a contingency as this, I have given, in fig. 3, a cover to the water chamber of fig. 4, intended to close it upward, and thus adapt it to a fall of any height; the water entering into this chamber from a large pipe A, of the required length: and being compressed accordingly, the result is forcible in proportion.

A few facts on the above subject will not be uninteresting. When this wheel, fifteen or sixteen years ago, (for I have forgotten it’s exact date) was about to be put in motion at La Ferté in France, several knowing ones took upon them to say “that it would not turn at all.” But who so astonished as they, when, at twelve feet diameter, and with less than five feet fall, they saw it make fifty-four turns in the first minute! I acknowledge, with pleasure, that these men soon expressed their approbation with unsophisticated candour; for although an honest prejudice had beset them, it was un-poisoned by that envy, I have more than once had to deal with in a country we are accustomed to call better! I therefore take leave, on this occasion, to say to my beloved countrymen, “Go and do likewise.”

OF
A NEW SPINNING MACHINE,
Called, and being the Patent Eagle.

The present Machine then, is a superior kind of throstle, the construction of which will be understood, by spinners, from the annexed figures, 5 and 6 of Plate 40. As the principal difference between the former machines and this, resides in the toothed wheel by which it’s spindles are turned, we shall begin this description by adverting to it: A B is that wheel, cut, at present, into 800 inclined teeth, and working with pinions of 11 teeth, one of which, with it’s spindle, is shewn at a b, fig. 6. The revolutions, therefore, of these spindles to one of the wheel, are 72.7272, &c.; and since the latter, in spinning, makes from 60 to 70 turns per minute, the spindles run at the rate of 5000 turns in that time, and might do more if desired by the spinner. In a word, the useful speed depends on the size and weight of the spindles, the flyers, &c.

Immediately above and below the wheel A B, are two rings of cast iron, to which are screwed rims, either of wood or metal, destined to hold the steps and bolsters of the spindles, as is usual in a throstle, with the difference of the circular form, which the wheel of course requires; and the relation of which, to the rollers, is shewn at a b, fig. 5, being a plan of this Machine. Returning to fig. 6, the next object upward is the roller-beam, (cast hollow for lightness) the form of which is that of an octagon, with two brackets c d, by which it is fastened to the pillars E F: these, in their turn, being connected with the top and bottom cross-pieces (G H, I K) so as to make up the frame, properly so called. All these parts are placed (in section) similarly to those usually composing the throstle; and the copping motion is produced by the curve f, driven by an endless screw on the shaft h f, and acting on the slide f g, and through it on the ring of which the square i is a section: and on whose iron plate, in fine, the bobbins drag, as they do in the throstle. In the Machine before us, the rollers are driven by two side-shafts h f, which take their motion either from a train of spur wheels placed above the traverse G H, or by bevil wheels from two small shafts, coming under that traverse from the central shaft L M, to those h f, and acting on the rollers by means of the bevil wheels f m, seen in the figures. Now, the rollers are contained in eight heads—1, 2, 3, 4, 5, 6, 7, 8, each of which has it’s speed wheels in the angles n o, &c. and receive their motion from six sets of bevil wheels q, &c. which propagate the motion round each half of the Machine, from the points m and p respectively.

Above this roller-beam, is the creel-ring N O, which (either in one or two rows) receives the sixty roving bobbins that supply the sixty spindles, of which the Machine is composed: and whose threads pass under the eight sets of rollers—one thread being suppressed in each of the heads—1, 4, 5, 8, on account of the columns. (This, at least, is the arrangement I prefer; but some of the Machines have been made with eight threads in all the compartments.) Finally, in this frame G H, I K, is placed a ring P Q, (of glass or bright metal) over which the rovings are thrown before they are put in the guides behind the rollers; so that the route of a thread in the act of being spun, is shewn in fig. 5, by the line P R, S b, where it meets the bobbin on the spindle a b, before mentioned.

It may be observed here, to prevent ambiguity, that the guide-boards, with their hooks, are placed below the octagon roller-beam q n o, &c. as they are in the common throstle; being, each, ¹⁄₈ of the whole circumference, and of a circular form on the outside, reaching, by these hooks, to the point S, so as to hold the thread just over the centre of the spindles as at a b, fig. 6. Considering this as a commonplace subject, I have not attempted to draw these boards, since their form and position would occur to every constructor: and this is the reason also, why I have given only the section of the copping ring i, fig. 6: nor at all shewn the top rollers—nor the detail of the creel—on all which topics, opinions vary considerably, while the things themselves are really of minor importance.

There is, however, in my Patent System, something which I think important, and which, therefore, I have sketched near Q, fig. 6. If w x be there considered as the second communication shaft, a wheel z is put on it, of that kind which is calculated to work in a certain geering chain, called in French chaine de Vaucanson, (from the name of it’s inventor); and further, similar wheels (y) are connected with all the pins on the creel, round which the chain is carried from the wheel z, till it comes to it again. The consequence is, that all the wheels (y) are turned by that chain, so as to untwist the roving while the spinning rollers draw it off the bobbins: and this is so, because, in my Patent System, the rovings are over-twisted, in order to admit their being made very fast, without the danger of breaking. This then, completes my Patent Eagle, formed, on the right hand of the figure so as to use over-twisted roving; and on the left hand, so as to spin common roving in the usual manner. In both cases, the motion of the spindles by geering, ensures a mathematical twist, and thus produces yarn better than common; whence also it’s fineness can be carried much farther than on a common throstle. It need hardly be added, that these spindles are stopped and set in motion by the mechanism described in my second Part, at fig. 1, Plate 19: and there mentioned as “a Machine to set-on and suspend rapid motions.”

OF
A SECOND SPINNING MACHINE,
Adapted principally to Wool.

This Machine, represented in Plate 41, figures 1 and 2, may be called a Spinning-card: whose use, however, I shall now suppose confined to spinning coarse yarn, or rather rovings, to be re-spun on the common machines, or on machines similar to my Eagle just described. It consists, in reality, of an horizontal card A B, having it’s flyer, &c. adapted to perform, in a perpendicular position, what those several parts do, in an horizontal one, on the common carding engine. All this is so well known, that I have not thought it necessary to draw it in these figures; but merely to say, that in this Machine, those operations are performed on the left hand, as at A, where is introduced a broad flat ribbon of wool, duly made on a preparing card, and laid on edge in a box at C, from whence it is drawn by the feeding rollers, &c. so as to cover the whole of the central card A B. Now, round this central card, are placed, ten or more small fillet cards, 1, 2, 3, 4, &c. being at different heights on the central one; by which arrangement, the whole surface of the latter is stripped by these cards, and as much filament collected on each, as is sufficient to form a thread or roving, as before mentioned. But, further, these small cards have to be stripped in their turn: and that is done by the circular combs a b, which being placed obliquely to the cards, receive motion from them, and gather a regular mass of filament of a size fitted to become the yarn or roving in question. Nor need this roving be re-drawn, by rollers, before it is twisted: for it is the property of the bobbins D E, fig. 2, to draw mathematically: and with any speed that shall have been determined. If we examine how this is done, we shall see at bottom, two wheels F G, (toothed on the patent principle) one of which drives the spindles and flies, and the other the bobbins D E: the wheel that drives the bobbin having a few teeth more than that which drives the spindles—whose pinion is the same in number as that of the bobbin. Thus, therefore, the bobbin goes as much faster than the spindle as is necessary to take up all the wool furnished by the comb, and to the comb by the small card, which receives it from the central card A B; where note—that the draught, by this difference of motion is not variable, but determined: since the heads of the bobbins E D, are a hollow inverted truncated cone, on which the yarn cannot remain—for in winding, it drives downward that which is already wound, so as to fill the whole bobbin from the head—a reason for the conical shape of the latter object.

It will appear by the upper figure, (which is a plan of the central card, and the small cards, 1 2, &c.) that the latter receive their motion from the chain H I, by means of the train of wheels K L, turning on studs in the upper cross-piece. Suffice it to add, that the centres of these cards, of the combs, &c. are fixed to the rings by proper cramps, as will be easily conceived. I have offered to sight, only the essential parts, to avoid confusion: and I presume to hope every thing important will be thus seen without difficulty.

In my present view of this Invention as a preparing Machine, I would observe, that the central card is only considered as a distributor, and that I should, now, add to it a System of machinery to make it a forced distributor. I had, indeed, prepared this very System to be patentized many years ago: but the delays that occurred then, followed by the Restoration, (which gave me an opportunity of coming to England;) made me suspend this intention—respecting a method, perhaps, the only thing wanted to make this Machine in all respects excellent.

In the small figure 5, (Plate 41) x y is supposed to be the section of a central card, such as A B, fig. 2; and the horizontal lines between x and y, shew the height of the card teeth. Of these, I take out a portion in several perpendicular lines round the card—say, at an inch distance from each other: the intervals thus stripped, being about ¹⁄₁₆ of an inch in width: and in all these upright slits, I introduce a blade x y, (whose transverse section is like that of a card wire) and whose edge is undulated as at a b. Finally, to these blades is given, (by a proper Machine) a slow up-and-down motion, which makes them push off the filament from the card wires at the highest points of the waves, and suffer the wires to retain these filaments at the lowest points; whence it follows, from the motion just mentioned, that these points of reception and exclusion of filament, are constantly changing on the surface of the whole card, and that, therefore, the card will never be totally clogged with wool—as it is in the common process. It will be seen that the use of this System need not interrupt that of the common flyer, (or stripping card) whose use is to keep the teeth in working order, and to discharge a part of the obtruding filament.

In terminating this article, I cannot resist the desire of recommending this whole subject to any opulent English Manufacturer, whose zeal and public spirit, are commensurate with the scope which these hints embrace, and to which they tend, if duly appreciated.

OF
MY PARALLEL MOTION,
As applied to HEAVY Steam Engines.

While this Invention, as described in page 30 of the first Part, is allowed to possess curious properties, and to be a pretty thing, opinions do not all concur in declaring it, essentially and generally, a good thing. Nor could I be unjust enough to insist that it is so, in every kind and magnitude of application. I have, however, convinced myself that it is susceptible of practical excellence, as a first motion to steam engines, whatever be their dimensions; and have, therefore, presumed to re-produce it, with those modifications which are required to make it so. In thus acting, I have again preferred the useful to the agreeable, and in some measure inverted the order of my subjects. But I trust this deviation will be excused, in favour of the motive and the result; on both which I feel a good degree of confidence.

To obviate the point of mechanical weakness in this Parallel Motion, (see Plate 41, fig. 3,) I have doubled it’s parts; and brought the piston rod a b, to act, at once, on two of the circulating wheels c d, placed exactly opposite each other, and rolling, as before, on the inside of the fixed wheels f e, so as to produce the rectilinear motion, by the action of the piston rod on them both. And to make their respective motions one, (as connected with the fly B A) this latter is fixed to a shaft common to the two wheels g h, and by which, therefore, the two other wheels i k, fixed to the crank shafts m n, are kept in due position. Thus, then, is all winding or twisting motion done away: and, therefore, can this System be employed in engines of every required power. Nor need I add, (what will be generally allowed) that much of the expence, and of the retardation, which a given engine suffers from the beam, the connecting rod, &c. will thus be completely obviated.

I must, however, stop every gainsaying mouth, on the circumstance of using geering between the engine and the fly—a system which I acknowledge to have been hitherto an evil; though, perhaps, a necessary evil—as giving (by a simple method) a double speed to the fly from a single motion of the piston. At all events, in this shape, I submit only to a very common difficulty—and might there rest my apology.

But I should have hesitated to go thus far, had I not foreseen that all the evil arising from this use of wheels, can easily be avoided by my geering:—by means of which I am bold to say, every vestige of shake or backlash may be destroyed; and this method of working a steam engine be made as silent as when a beam is used: in which case, considerable advantages must accrue from this method.