“The fourth figure in this Plate 18, presents a general view of the vessel, comprising five articulations, (or Boats) besides the head and stern—which latter would fit each other without any intermediate parts, and form a Boat alone. Nor do these five parts by any means limit the useful number: but the Plate would not have contained more, unless on a scale too small to be distinctly understood.”

“Returning now to fig. 1, we observe the ropes A D F H and B C E G, which are supposed fixed to the stern Boat, and carried to the capstans represented in the Head. These ropes consolidate the whole fabric, and act, occasionally, as a kind of muscle, to govern the larger evolutions. These ropes pass in the brackets placed near the joints A B and C D, &c. being under the gang ways, of which a portion appears at S fig. 3, hung upon hinges, that they may be turned up when the Boat is used in narrow water.”

To the above specification were added the following remarks, which still apply to this kind of vessel, navigating on canals and inland rivers: “this vessel admits of the use of every kind of mover; such as men, horses, wind, or the steam engine; the latter of which I propose to apply to it in a manner equally simple and effectual; especially so as not to injure the banks of any canal, &c. by acting against and disturbing the water.”

I need not repeat that this Invention dates as high as 1795: as the Brevet was issued in that year. It may be added that four parts of such a Boat were executed about the same time; namely, the head, the stern, and two intermediate pieces: making together a length of 100 feet; and these, loaded to a certain depth with stones, were drawn up the river Seine by a single horse on a trot—which would likewise have taken place had the Boat been ten times as long; since, as before mentioned, the resistance of this kind of vessel bears no given proportion to the Load it carries.

OF
A MACHINE
For destroying, or lessening Friction.

I think it may be assumed that friction is fully expressed by the word rubbing: and that where rubbing cannot be found, friction does not exist; especially that kind of friction which opposes the motion of machinery—in which respect, the subject is chiefly thought interesting to mechanicians. It would be abandoning my intended plan in this work, to treat largely of friction, or any other accident in practical mechanics; but having already declared myself “no believer in several sorts of friction,” I am in a measure bound to introduce my description of the two following articles, by a short reference to the general subject. I offer then the following remarks, more as hints for the consideration of learned experimenters, than as conclusions sufficiently proved to become rules in practice. What I cannot help urging strongly is, that rolling is not rubbing. If it were, I would ask in what direction it takes place? Is it in that of the plane rolled over? or in that of the radii of the rolling body? If in the former, it would indeed glide over that plane, and occasion or suffer real friction; but this, I think, is not pretended. If this motion is in the latter direction, (that of the radii of the rolling body) it is indefinitely short, compared with the progressive motion of the rolling body, so that the power of the latter, to overcome any resistance in that direction, is infinite. Whenever therefore, in experiments of this kind, a finite resistance is perceived, it must, I should think, be ascribed to other causes, and not to friction. In my wheels for example, (see a former article) where there is a real and deep penetration of the surfaces, I have proved that the friction between the teeth is less than the distance between two of the last particles of matter: and surely, when penetratration is purposely made as small as possible (by the use of smooth rollers) the friction thence arising must be still more imperceptible. But I hear it answered, that this friction is both known and measured! and certain celebrated experiments are adduced to prove it. But what I most wonder at is, that a person so truly learned as the author of those experiments, should have adopted so remarkable a misnomer; in which to all appearance, indentation has usurped the name of friction. Nor let this surprise, surprise any body: nor especially, offend this learned author himself; for I am persuaded that the sole act of placing these wooden rollers, on these surfaces of wood, must indent them both sufficiently to account for all the facts observed; and still more so when loaded with weights of 100, 500, or 1000lbs. No friction, therefore, is requisite in accounting for the resistance of these rollers to horizontal motion. Nay, I submit, whether a resistance, arising from indentation alone, would not prove to be “directly as the pressures and inversely as the diameters of the rollers?” To me the subject presents itself under three aspects: either the whole indentation takes place on the rollers, when they are very soft and the rulers very hard; or the latter, when they are very soft and the rollers very hard: or, which is most likely, this indentation takes place on both bodies at once; so as to produce a surface of contact, intermediate between the straight surface of the rulers, and the cylindrical surface of the rollers. But in either case, the place of resistance to horizontal motion, must be out of the line of direction of the roller’s centre of gravity: and thus would the roller present more or less resistance, independently of every thing that can be called friction: and which degree of resistance will continue to exist as long as the place of contact is made to change on the rulers—for thus to change this place of contact is to renew this indentation; which process will elicit a resistance equal to what would be observed were the roller (without indentation) forced up a plane, inclined to the horizon in the same angle as a line, drawn from the centre of the roller to the extreme edge of the surface of contact, makes with the perpendicular.

I cannot possibly enter at length into this subject, as it makes no part of my engagement to the public: but I would observe that this resistance is, a fortiori, something besides friction, since greasing the surfaces “did not cause any sensible diminution of it;” whereas it made a difference of one half! in some others of the experiments alluded to.[4] Were I asked the reason, I should answer, because friction had little or nothing to do with it; and I would say further, that greasing or oiling these surfaces would most likely increase, instead of diminishing, their resistance to horizontal motion: namely by softening them, and making them more susceptible of change of figure: which opinion gathers strength from another fact adduced, viz: that “rollers of elm produced a friction (or resistance) of about ²⁄₅ greater than those of lignum vitæ:” but why? because elm is relatively soft and lignum vitæ hard—the only cause that appears sufficient to account for the facts observed.

I must now leave these remarks to persons having more means and leisure than myself, to pursue the subject; wishing only, that useful truth may result from them: and that this unbelief of mine “in several special kinds of friction,” may at least be found to have some reasonable ground to rest upon.

But I may be opposed in some of my statements by the fact, that friction rollers, with centres, have been used with little advantage; and often laid aside. This I acknowledge; and go a step further. Friction is by no means of so much consequence as it was once thought to be: and is not the source of the greatest defalcations that occur in the use of power. Yet, to get rid of it, in some cases, would be of considerable importance; and the subject deserves at least the attention of every intelligent mechanician.

Those who have used friction rollers, know that it is a thing of great difficulty, to place their axes exactly parallel to that which they are intended to support: and even, if rightly placed at first, that a small degree of abrasion, greater on one pivot than another, will soon destroy that parallelism; and thus introduce a growing friction, capable, at length, of rendering the whole completely useless: for although the original friction is lessened by being transferred to a slower-moving axis, yet the latter still resists in some degree, say ¹⁄₄ of the whole; (its pivots being ¹⁄₄ of its whole diameter) so that the cohesion, or something else, between the main shaft and the friction roller, (thus resisted) must be sufficient to drag round the latter, against about ¹⁄₄ of the original friction; which in a word it cannot do without some relative motion between those surfaces, the friction roller lagging behind the main shaft, until its own friction is overcome by another. And thus it is, that a friction roller of this kind, does not make so many revolutions on its pivots, as its diameter compared with that of the main shaft, would imply; for example, if the shaft were 4 inches in diameter and the friction roller 8 inches, the latter would not complete one revolution against two of the former. There would thus remain a difference spent in real friction, in addition to that on the axis of the friction roller. Besides this, we have the want of parallelism above mentioned; which occasions a rubbing, in the direction of the shafts, small indeed in quantity, but for that reason very powerful in bringing on a change of form, and thereby hastening the common destruction. Both these accidents, therefore, make friction rollers, in general, an unsatisfactory and perishable expedient: and it is to make them less so, if not entirely to cure these evils, that the two following articles are designed.

In fig. 6 of Plate 17, A B is an axis which it is desirable to divest of its friction. To do this, as nearly as may be, I connect with it two rings of hard metal C D, formed as truncated cones; and under the shaft, in the same vertical plane, I place two smaller shafts E F, carrying on their tops, other two cones, similar to the former. The summits of each pair of cones meet of course in the points a b of the main shaft; and, on the principle of bevel geer, every contiguous part of the touching cones moves with the same velocity: so that there is no sensible rubbing between them—for, 1st. the pivots c d, are hard and pointed, and run on the hardest steps that can be obtained; and, 2ndly. the tendency of the cones u toward each other, is repelled without friction by the cylinders e f, attached to them, and which lean right and left against each other, turning with the same velocity, without causing any friction, or any creeping, between the two pairs of cones e C, and f D. All the weight therefore, of the shaft A B, (which of course is kept in place in the other direction by proper side cheeks, &c.) rests on the points of the vertical shafts E F, accompanied by no sensible tendency of these points to quit the places assigned to them.

OF
A SECOND MACHINE,
To avoid or diminish Friction.

In Plate 17, figs. 7 and 8, offer a mechanism different from the preceding, though intended to produce a similar effect. Referring to that cause of friction which consists in the want of parallelism between a principal shaft and its friction rollers, I here introduce a form for the latter, which admits of this consideration being in a measure neglected. These friction rollers are only portions of cylinders; and they have no shafts. They turn simply on a sharp edge, placed in a prismatic box A B, in a well formed angle of which, they move to and fro, without rubbing. When at rest, these axes D C D, (fig. 7 and 8) are drawn against the right hand side of the box, by small weights E; and the shaft is carried by one or the other of them, according as they are, or are not, within reach of its radius. Thus, in the present position of the shaft, (see fig. 7) the second arc C supports it, the third having fallen behind the first, so as not to be seen: and the first arc D being on the point of taking up the load. In short there are six spaces, either left or cut on the shaft, opposite the three arcs D C D. 1st. one space, of ¹⁄₃ of the circumference, left concentric with the real centre of the shaft, opposite the first arc D, followed by ²⁄₃ of a circumference cut an eighth of an inch lower. 2ndly. another third of a circumference opposite the second arc C, beginning where the first ends, and followed by ²⁄₃ of a circumference cut an eighth of an inch lower: and 3rdly, another space of ¹⁄₃ in circumference, opposite the arc D, followed by a similar space of ²⁄₃ cut an eighth of an inch lower. By these means the shaft is never without a concentric bearing: and the better to secure this property these arcs left, may be each of them more than one third of a circumference in length, so as to avoid the least drop at each change of roller; and even to give the shaft a support from two rollers at once, during a good part of its revolution.

In using this mechanism, the vessel A B, would be filled, to a certain level, with oil or water, to prevent any blow from the returning arcs—which latter might be made to fall on a lining of leather, to avoid still further all commotion: and thus, even were these rollers not placed quite parallel to the shaft, this imperfection would be corrected by the frequent renewal of these movements, and the consequent absence of lateral friction between the arcs and the shaft. It may be observed that either of the above methods of destroying friction is not confined to the vertical direction: but may be so used as to receive the pressure caused, in any direction, by the action of a wheel or other agent. And with respect to the best use of each method respectively, I would propose the former for light and swift motions, and the latter for slow-going shafts, heavily laden: it being well understood that the shafts must be kept in their places, in the less essential directions, by proper steps, at the discretion of the person who employs these Machines.

Finally, I consider it as a matter of course, that all the surfaces coming into contact in these operations, should be as hard and impenetrable as possible. For if, by neglecting this precaution, any change of form occurred, what is said above could not be practically true: But these properties can be realized, with only those degrees of hardness that are often employed in the mechanical world. Thus a die of hardened steel, bears almost unimpaired, the strokes and pressure it suffers in the coining-press. A chisel, stands thousands of blows and cuts hard metal, without sensibly giving way. The knife-edges which carry a heavy pendulum, suffer it to vibrate many years without wearing out; and the fulcrums of scale-beams, bear enormous weights, for almost an indefinite period, without any injurious effect. I request therefore, that these facts, may be put into the scale, when my foregoing statements are tried: whether as applied to these anti-attrition machines, or to my late patent wheel work, or both combined: for I foresee the use of these friction rollers, cut into teeth on that principle, to insure the proportionality of their respective motions.

OF
AN EQUILIBRIUM COCK,
To prevent abrasion and leakage.

Fig. 9, 10 and 11 of Plate 17, represents one of the forms of this equilibrium Cock. It consists of a square plug case or chamber a b, with a hole c d bored transversely through it, exactly across its centre: and to this chamber is fixed by the flanches e f, the bifurcated water-passage g h, forming one body at i. The plug of this instrument admits of various forms and proportions; of which I have shewn two in the figures 9 and 11. The first m n, receives the fluid through the two openings c d, which correspond, in one position of the plug, with the double water-passage before mentioned. And further, the plug itself is bored lengthwise in its under end n, so as to form the spout of the cock: or otherwise (see fig. 9) this spout is taken in a double form from the outer surface of the plug at b a, so as to present two streams, thus producing, I think, an instrument of somewhat greater solidity. All that seems important is, that whatever be the pressure of the fluid from without, it be made equal on both sides of the plug, so as to occasion no friction between it and the chamber. The principle is indeed so effectual, that one might distribute steam pressure of the greatest strength or even gunpowder pressure, without much resistance to the operator, and without injuring the mechanism by oft repeated action.

OF
A MACHINE
To communicate and suspend Motion.

In Plate 19, figs. 3 and 4, shew this mechanism in two directions. It is composed of two wheels C D, cut (or cast) into teeth of a peculiar kind, that both geer with one another, and at the same time, include the chord or round strap A B, by which they are driven. These teeth can be better represented by a figure than in words; and will I suppose be understood from figures 3 and 4: They are divided, on the rim of each wheel by a space too small to admit a tooth of the other wheel: but then, every-other tooth is cut away in a sloping direction on each side of the wheel, from the bottom of the tooth to its top on the opposite side: so that while these teeth are working in each other they offer two grooves, in the form of a V, which coming together surround the chord and press it in four points, either to drive the wheels by the cord, or to pull the chord by the wheels, according to the use it may be wished to make of this mechanism. In fig. 4 the cord is seen at A B, passing among the teeth of the wheels; and in fig. 3 it is shewn at C, as a mere circle, in the centre of a lozenge formed by the teeth whose points now geer together. Fig. 5 is a sketch belonging to this subject, which shews something of the manner of using this round strap as a mover: for by carrying it (either in a horizontal or vertical plane) by a line slightly curved, from one machine to another, it will drive them all and give the means of stopping any one at pleasure. Suppose then, A B C D fig. 5, to be four machines placed as above mentioned. If I wish to stop the machine B, I merely draw back the pressure wheel E, and the cord ceases to lay hold on the machine as shewn by the dotted line: but when I want to set it on again, I do it by bringing back the wheel E to its present position. And thus at a small expence, I could geer a considerable factory, in a way which I think as durable as it appears economical. The principal objection, perhaps, is that this cord is liable to wear out soon, by such incessant action; but then the pressure on it needs not be great; and of friction properly speaking there is very little: Besides which, the cords would be made of a peculiar texture, perhaps of leather, sewed edge to edge and covered like a whip, by one of the machines I shall bring forward hereafter.

It so happens that many of my Inventions are of a generic nature, and thus apply to cases which, appearing different, have nevertheless some common properties. The rule of contraries especially applies to many of them,—of which this is an example. It offers a good method of driving a boat through a tunnel, or other confined space, either by the force of steam or any convenient power. To this end a rope laid along the side of such canal, and fixed at each end, or at several intermediate points, might be led between a pair of wheels like those above described; which duly turned, would drive the boat the distance required with the least possible expence of power, and without the defect of agitating the water.—But I must not anticipate too much on my intended subjects.

OF
A MACHINE
To set on, and suspend, rapid Motions.

This Invention is under the protection of a Patent. It is applied to the spindles of my spinning machinery called Eagles, from their analogy to the machines named Throstles. It is in my opinion an excellent machine; as it secures a mathematical equality of twist to any number of spindles from permitting the use of geering to turn them, which could not have been done without some means of stopping a single spindle. This mechanism (see Plate 19 fig. 1 and 2) consists of a toothed pinion A soldered to the box B C, (partly cut down in the figure to shew its contents) and with it running loose on the lower part of the spindle E D. In this box are placed two weights M N, like that M fig. 2, which both together, fill the box loosely, and, rising above it, are pinned at O P through the spindle. They are moreover kept from quitting the latter by the ring shewn in section at q q, which holds them loosely, yet prevents their flying away or hurting any one. When now the spindle E D, turns swiftly, the centrifugal force of the two weights M N, projects them from the centre as far as possible; and they lay hold, by friction, of the cylindrical surface of the box B C, and thus keep the revolutions of the spindle to the same number of turns per minute, as the pinion A receives from the driving wheel. But when the spindle is stopped and held by the fly as usual, then the centrifugal force ceases to act, and the box B C does not wear out much, by its further revolutions. And when as before, the spindle is again let loose, that friction which takes place on the bottom of the box sets the spindle running again, when the centrifugal force comes to its aid, so as to unite again the box and the spindle, thus renewing that valuable property of all spinning machinery, the mathematical correctness of its movements.

OF
A MACHINE
For forging Screws, Beads, &c.

The effect which this Machine is intended to produce, is analogous to several culinary or officinal processes that might be named. It is called rolling: but not in the same sense in which that word is used in manufactories, where rollers form or modify the body acted on. Here this body itself rolls between two surfaces moving different ways and receives from them the desired impressions, and this idea I have extended to screws; proposing to finish them on some metals and in some dimensions; and to rough them out in others. The Machine is represented in figs. 6 and 7 of Plate 19, where fig. 7 shews the faces of the arcs A B of fig. 6. By the form and connection of the arms A C and B D, these arcs move opposite ways: and since they are grooved obliquely as shewn in fig. 7, if a prepared cylinder of soft metal a, be put between them, and the handle C be sharply pressed into the position A E, the cylinder a will be made to roll, and the grooves of fig. 7 be impressed on it so as to meet and form the screw in question. The only conditions are, that the arc B A be at least equal in length to the circumference of the screw, when finished; and that the grooves (fig. 7) be rightly sloped, and have the form intended to be given to the threads of that screw. It will occur of course, that the opening between the arcs at the point where the blank cylinder is introduced, must be larger than the distance between the arcs by the whole depth of the threads to be impressed: which therefore will begin to be formed at two opposite points the moment the screw a begins to roll. This however, might and would be otherwise, if it were thought best to form the arcs A B spirally; and let the deepening process be gradual: in which latter case another consideration would occur, namely; that the grooves themselves (see fig. 7) must diverge a little instead of being parallel, so as to permit the screw to lengthen as the pressure should displace a part of the metal. In all cases the upper surface of the grooves should be milled so as to lay hold of the soft metal, and insure the rolling motion: and should this material be hot-iron, the stroke should be taken in an instant, and the machine be kept cool by every proper method, in the intervals of working.

I need not add that this rolling process would be still easier performed, if the impressions to be made were circular and not oblique: such as beads, balls, &c. but these considerations I leave to my readers.

OF
A DIFFERENTIAL STEEL-YARD,
To weigh vast Weights with short Levers.

Plate 19, figs. 8 and 9, offers two representations of this Machine—one intended to shew its manner of acting, and the other one of its practical forms. By means of the first, (fig. 8) we may compare it with the common steel-yard; and even shew the latter as a part of the former. If a weight, or load to be weighed M, were suspended to the arm A B, and the counter-weight W, placed at the point C, of the arm A C, we should have a common steel-yard whose power would be as 5 to 1: for the arm A B is just ¹⁄₅ of the arm A C, and this is the principle on which steel-yards are commonly made. But instead of this, my steel-yard G E B D C H fig. 8, is now infinitely powerful: so much so indeed, as to be infinitely useless. If millions of pounds were now to be suspended at P, they would not raise the weight W one tittle, for they hang entirely on the point of suspension A. But although the Machine is now useless, it can be altered in a moment and made both useful and commodious; only I thought its principle would be the better understood from being thus shewn in excess. To make it a useful and powerful Instrument, I only move the hanging bar D G, to a b; and the bar E B to c d, the lever b d being similar to that E G. In this state of things, the whole load P is found at the point o of the lever B H, (for the lever-arms c o and d e, and those e b, and a o are equal) and the power of this steel-yard is as the line A C to the line A o; that is as 20 to 1, instead of being as 5 to 1 which it before was. But this is not yet a powerful Machine; being chiefly intended to shew the principle on which it acts—and to prove that however small the distance A o, that distance, dividing the arm A C, gives the real power of the steel-yard. And supposing now the arm A C to be four feet in length, and the distance a D, B c, and A o, to be ¹⁄₁₀ of an inch, then the power of the weight w to raise (or weigh) the load P is as 48 inches to ¹⁄₁₀ of an inch, or as 480 to 1: so that if the weight w were 10lbs. this steel-yard would weigh 4800lbs. or upwards of two tons; and it is easy to see that this power can be almost indefinitely extended.

Fig. 9 of this Plate shews a real steel-yard made on this principle; the power of which, under its present length, is as 40 to 1. In this Machine all the centres are fixed: and the load is suspended on knife-edges, the distances of which from each other and from the common centres are invariable—as they must be in all instruments of this nature.

OF
A RETROGRAPH,
Or a Machine to write backwards, for Engravers.

This Machine is exhibited in the two figures 10 and 11 of Plate 19. It is composed of a straight ruler A B, having an exactly dove-tailed mortice made along it, to receive the rollers, (or slides) by means of which the parallelogram C D E F slides up and down in this mortice. This parallelogram is composed of four rulers C D, D E, E F, and F C, connected by cannons or tubes fixed to every-other arm: and on which the contiguous rulers turn very correctly. Through which moreover, in two cases, F D the drawing pencils are introduced, and under which in other two cases, C and E, the guide rollers already mentioned are nicely fixed by the screws on which they turn. This is seen by an elevation in fig. 10, where p marks one of these rollers, and o q the end of the ruler supposed fixed to the paper by proper blunt points, &c. At r is seen one of the tubes which form the joints C and E: and r t, are, one the writing pen, and one the retrographic style or pencil. Fig. 11 is a plan of the whole Machine: where if the hand guiding the pen D goes upward, the tracer F rises too. But if the pen or hand D moves to the right, the tracer moves to the left at the same moment. In a word this is to write backward in the sense of engravers, who thus write that their letters may proceed forward after one impression.

If it were desirable to give the engraver the same facility he has in the use of a pen, the tracer t, fig. 10, would be terminated above as a hollow conical cup, into which he would introduce a pointed style held as a pen. In this case the tracer t, would be made as short or low as possible, to bring the style so much the nearer to the paper; and thus to prevent all anomalous movements.

OF
AN EYE MACHINE,
Or Machine for making the Eyes of Hooks and Eyes.

If it were enquired why this Machine is offered to the public without the Hook Machine; the answer would be, this only is finished: and it is wished to present nothing here that admits even a doubt of its utility. The drawings given in Plate 20, figs. 1, 2 and 3, are more intended to be useful in the construction of this Machine than complete in appearance: so that nothing has been done by way of shading, but what it was thought would the better distinguish the parts from each other, and facilitate their assemblage in one effective Machine. The Machine consists first of a slide A B, (worked by a lever-handle, a crank, or any proper first motion.) It glides between two cheeks C D, (see the end view in fig. 1) connected with the several parts about to be mentioned. This slide is marked A B in all the three figures. It carries (by means of the screws a b, coming through the slits c d, in the main Plate E F) a plate g, the chief use of which is to support a tumbler e, whose use is to throw the eye, when made, from the machinery: which tumbler is kept to its work by the spring i, as will be further explained presently. This slide itself has a peculiar form at the end B, (fig. 2) which is shewn by dotted lines at c d in fig. 1. It is a slit, with the corners rounded off for the purpose of working the springs now to be described. These springs m n, (see fig. 2) are fixed to a cock, itself screwed behind the main plate: and they come through the latter to the left-hand-ends of the small curved mortices seen (with the springs) at m n fig. 1. The slide A B then, with its forked end shewn by the dotted lines at c d, is destined to take the springs m n and carry them to r s, where they are now seen surrounded by the eye almost formed: for in this motion these springs take the wire (shewn by the lines dotted across the Machine and previously cut by the sheers u) and meeting with the obstacles t v, being the thicker parts of the clams t v w, they bend it into the form r s—when the screws a b lay hold of the sloping ends of the clams c t w v d, and squeeze them together; by which operation the hooks t v finish the eye, by rolling its two ends round the springs m n now in the position r s. Where note, that the slit c d of the slide A B is so formed as, when it has carried these springs m n to r s, to slide forward without doing any thing more to them, while closing the clams. It performs, however, some other less important operations, to which it is now necessary to allude: among other things this slide works the sheers u that cut the wire, and that, by means of the doubly wedged hook x, which goes back with the plate G, doing nothing: but which by the action of its springs fixed at a, falls under the sloping end of the sheers u; and, when the slide, by the screw b, carries it to the right hand, raises the end x of the sheers u, and cuts the wire near v, to prepare it for the operations already described. The part y in the two figs. 1 and 2, is the other cheek of the sheers fixed by screws to the main plate, and covered by a small plate z, in which a nick is cut to form a passage for the wire, and present it to the sheers, that they may cut it to the proper length, after having directed it right across the springs r s, then placed by their elasticity at m n. It hardly need be added that a stop is placed at o, to determine the length of the wire so as to form the eye complete, and not to admit more wire than is sufficient; all which is regulated between the sheers and the stop, by proper adjusting screws, which it is very easy to suppose or supply.

Fig. 3 is intended chiefly to shew the mechanism by which the eye, when finished, is thrown off the pin round which it is bent by the springs m n. It consists of a tumbler e, placed in a mortice in the end of the plate g, and kept to a given position by the pressure of the spring i. When the slide A B is carried forward, toward E, to perform the operations already noticed, this tumbler e, gives way to the angle G of the doffing lever m G, (this lever being shewn also between c m & d n in fig. 1) and rides towards m without producing any effect either on the plate G or the lever m G: but when it has once passed the said angle G, it cannot go again toward F without depressing smartly the end G of that lever, and thereby raising the end m, thus starting the eye from the stud m, round which it had been bent by the processes above described.

At the right of fig. 1 near F, is an object, the use of which is too evident to need description. It is a double spring for the purpose of keeping the hooks c t w v d pressed against the pins, near t v, which determine the position of the said hooks; and the degree of bend first given to the wire by passing the points t v.

There are some less important parts and operations left undrawn, in order to prevent confusion in the figures: but they are such as would strike any person having the above under his eye. In a word I have done what I thought best to aid the construction of this Instrument:—which is represented at two thirds of its natural size—but whose dimensions, of course, would vary with that of the objects to be produced by it.

OF
A VENTILATOR,
Rotatory yet by pressure.