Part 4
“A, Plate 9, fig. 4, (of this Work) is a circular inclined plane, moving on a pivot under it, and carrying round with it the axis E. A person walking on this plane at A, and pressing against a lever, throws off a gripe or brake, and thus permits the plane to move freely, and raise the weight G by the coiling of the rope F, round the axis E. To shew more clearly the construction and action of the lever and gripe, _a plan_ of the plane connected with them, is added in fig. 5, where B represents the lever, and D the gripe: where it is seen that when the lever B is in the situation in which it now appears, the brake or gripe D, _presses against the periphery of the plane_; but when the lever B is driven out to the dotted line H, the gripe D is detached, and the whole Machine left at liberty to move: a rope or cord of a proper length, being fastened to B, and to one of the uprights in the frame, to prevent this lever from being pushed too far towards H, by the man working at the Crane.”
“The _supposed properties_ of this Crane, (says Dr. Gregory) for which the premium of forty guineas was adjudged by the society to the Inventor, are as follows:”
“‘1. It is simple, consisting merely of a wheel and axle:
“‘2. It has comparatively little friction, as is obvious from the bare inspection of the figure:
“‘3. It is durable from the two properties above mentioned:
“‘4. It is safe: for it cannot move but during the pleasure of the man, and while he is actually pressing on the gripe lever:
“‘5. This Crane admits of an almost infinite variety of different powers; and this variation is obtained without the least alteration of any part of the Machine. If in unloading a vessel, there should be found goods of every weight, from a few hundreds to a ton and upwards, the workman will be able so to adapt his strength to each, as to raise it in a space of time, (inversely) proportionate to it’s weight, he walking always with the same velocity as nature and his greatest ease may teach him.’”
“‘It is a great disadvantage in some Cranes, that they take as long a time to raise the smallest weight as the largest; unless the man who works them turn or walk with such velocity as must soon tire him. In other Cranes, perhaps, two or three powers may be procured; to obtain which, some pinion must be shifted, or fresh handle applied or resorted to. In this Crane on the contrary, if the labourer find his load so heavy as to permit him to ascend the wheel without turning it, let him only move a step or two towards the circumference, and he will be fully equal to the task. Again, if the load be so light as scarcely to resist the action of his feet, and thus to oblige him to _run_ through so much space as to tire him beyond necessity, let him move laterally towards the centre, and he will soon feel the place where his strength will suffer the least fatigue by raising the load in question. One man’s weight applied to the extremity of the wheel would raise upwards of a ton: and it need not be added that a single sheaved block (at the jib) would double that power. Suffice it to say that the size of the machine may be varied in any required degree, and that this wheel will give as great advantage at any point of its plane as a common walking wheel of equal diameter; as the inclination can be varied at pleasure, as far as expediency may require. It may be well to observe that what in this figure is the frame and seems to form a part of the Crane, must be considered as part of the house in which it is placed; since it would be mostly unnecessary should such cranes be erected in houses already built: and with respect to the horizontal part, by walking on which, the man who attends the jib, occasionally assists in raising the load, it is not an essential part of this invention, when the crane and jib are not contiguous: although, when they are, it would certainly be convenient and economical.’”
The Doctor continues: “Notwithstanding, however, the advantages which have been enumerated, Mr. Whyte’s (White’s) Crane is subject to the theoretical objection, that it derives less use than might be wished from the weight of the man or men: for a great part of that weight (_half_ of it if the inclination be 30 degrees,) lies directly upon the plane, and has no tendency to produce motion. Besides, when this Crane is of small dimensions, the effective power of the men is very unequal; and the barrel too small for winding a thick rope: when large, the weight of the materials, added to that of the men, put it out of shape and give it the appearance of an unwieldy moving floor.”
The Doctor continues: “We know one large Crane of this construction, which has an upright post near the rim on each side, to support it, and keep it in shape; and as much as possible to prevent friction, each post had a vertical wheel at it’s top.” (N. B. _I_ never saw, or heard, before, of this monster.)--“We were informed this Crane was seldom used; and that it was soon put out of order. Nor, moreover, is it every situation that will allow the Crane-rope to form a right angle with the barrel on which it winds; and when this angle is oblique, the friction must be much increased. The friction arising from the wheels at the top of the vertical _crutches_ might indeed be _got shut off_, by making the inclined wheel very strong; but this would add _greatly_ to the friction of the lower gudgeon of the oblique shaft, and _considerably_ increase the expence of the Machine.”
“There remains then (says Dr. Gregory) another stage of improvement with regard to the construction of Cranes, in which the weight of the labourers shall operate without diminution, at the end of an horizontal lever; and in which the impulsive force thus arising, may be occasionally augmented by the action of the hands, either in pulling or lifting”--and then follows the conclusion. “This step in the progress has been lately effected by Mr. David Hardie, of the East India Company’s Bengal warehouse!”
I cannot follow the author (whoever he be) of the glowing picture next given of Mr. Hardie’s Invention, (to which the obloquy thrown on my poor abortion is clearly _the foil_) as my readers must already be anxious to “get shut” of such unmitigated Bathos, bestowed on so trivial a theme. With respect to my Crane, I shall only say that it fulfilled the conditions required by the Society, _and obtained the Premium_: and if on the one hand, the language in which, thirty years ago, I described it, exhibits the impetuosity of youth, untempered with the moderation of age, I will say on the other, that if impartial criticism, mechanical acumen, or comprehensive _science_ are essential components of a mechanical work _of high pretensions_,--these qualities were seldom more wantonly abandoned or abused, than in the paragraphs above quoted: except, perhaps, in the attack of the same work, on the labours and character of the justly celebrated Watt, whose merits had this author known how to appreciate, he _could not_ thus have attempted to lessen in the public esteem.
But to return, this _Diatribe_ begins by comparing my Crane to a foot mill: and kindly supposes I did not know that its principle existed in Germany 150 years ago. But the fact is, my object was nothing like that of the author of the mill in question: the very figure of which, proves that _he_ had no view to the variation of power by change of place on the wheel: whereas _that_ is the principal use I make of this “unwieldy moving floor,” as the Doctor _heavily_ terms it. Again, this author asserts that by making men walk on an _inclined_ plane, I derive less use than might be wished from their weight; and yet! a page before he told us that “the mechanists on the Continent had long since insured the advantage of availing themselves of that addition to the moving power which the weight of the men may furnish;” so that poor _I_ have the merit of imitating them without knowing it, and yet of _not_ drawing the same advantages as they from the self same principle!
But again, “a great part of the weight of the man (_half_ of it, if the inclination be 30 degrees) lies directly on the plane, and has no tendency to produce motion,” which _one sided truism_ is placed there to give relief to the portentous _dictum_, which follows:--that “there remains then another stage of improvement with regard to the construction of Cranes, in which the weight of the labourers shall operate without diminution at the end of an horizontal lever: and that stage has been effected by Mr. D. H. of the East India Company’s Bengal warehouse.”
But is this conclusion definitive? are there no countervailing evils? Will Dr. Gregory presume to say there is no _disadvantage_ attending this advantage? Did the Doctor ever ascend an upright ladder? and did he _prefer_ that, to going up an easy flight of stairs? was he ever in the geometrical stairs of St. Paul’s? or in any large _winding_ stair-case? and if so did he prefer ascending close to the nucleus? or did he quickly seek a point where the step was _wider than high?_ most certainly the latter; and why then did he not perceive that if the weight of my man is diminished one half on the plane, for the very same reason, a given _elevation_ of his feet (on which his _fatigue_ depends) will cause a circular motion twice as extensive; yet this is quite as clear as the Doctor’s _ex-parte_ proposition.
But I must wade on a little further, trusting that my readers will exert a little more patience to follow me: for this same dictum of the Doctor’s accuses indirectly, the Society of Arts of being a set of blockheads, for remunerating an Invention with only _supposed_ properties. I really wish these self-constituted judges of other people’s labours would utter their oracles with more regard to truth and propriety! and above all, not mix up their passions (which alas! are not always purified by science) with their judgement on the merits of other men’s inventions. Had the author of this article been wise enough to proceed thus, he would not have _supposed_ me capable of offering _suppositions_ for realities; nor the Society of Arts of rewarding as genuine, _suppositious_ merit; and still less would he have emblazoned the very properties he calls _supposed_, with _reality_ written in glaring characters on every one of them! These properties are in fact only the transcript of what the society required of the candidates: and I therefore said my Crane is simple: Can this author say it is not? I said it has little friction? will he say it has _much?_ I said it is durable: Is it now possible to contradict this? I said it is safe: and will Dr. G. say it is not, when it is moveable, _only during the wish of the workman_: since _whatever_ suspends this wish, (whether accident or design) the Crane becomes of itself _immoveable_. In fine, I observed, that this Crane admits of an indefinite number of _powers_, without any modification of it’s parts; and can any one say these are _supposed_ properties? If the Doctor or his coadjutors persist in saying so, I must _suppose_ them actuated by improper motives; for truth will never bear them out in these allegations. I take leave to add, that but for the interests of truth, these strictures had never appeared. Even self-defence would not have provoked one line of them: But I felt it incumbent on me to deter, if possible, inadvertency as well as malevolence, from infesting with the thorns of misrepresentation, the paths which genius explores, in search of useful knowledge.
OF A DIRECT AND DIFFERENTIAL PRESS, _With two Powers: of which_ ONE _immense_.
The effects intended to be obtained from this Press, are to introduce two distinct powers; the one to raise and lower the pressing cap with convenient speed; the other to _press_ with _very_ great force. In Plate 10, A B is a frame, the under part of which contains the goods to be pressed. The toothed wheel C D turns the screw S, and that E F turns the nut G H, _both the same way_. The long pinions I K, turn both these wheels C D, and E F; and occasionally one only, as will be seen presently. L M are two bevil wheels on the axes of the long pinions I K; and N O, are two similar ones, on the power shaft P Q. This latter shaft runs in two boxes R T, the _stems_ of which fit and turn in the gudgeons of the long pinions, or rather suffer these to revolve round _them_: being pinned on through a circular groove which connects them in the perpendicular direction only. Finally, the rope and pulleys _indicated_ at X Y Z, serve to raise both shaft and pinions; thus disengaging the latter from the wheel E F, when the nut G H, is _not_ to be turned. We may remark, that the parts M T O are _doubled_ in this machinery, at L R N; merely to take away the side tendency from the screw S: as otherwise _one half_ of this mechanism would produce the very same effect, and leave the Machine the more simple. Supposing now, this Press charged with goods in it’s present position,
The wheel C D, having 69 teeth; } with proportionate that E F, „ 70 „ } diameters. The pinions I & K, each 10 „ The wheels L N & M O equal;
The thread of the screw S, 1 inch; and in fine, the crank V Q, having a radius of 18 inches.
In this state of things, the motion of the pressing cap W, is to the motion of the handle V, as 1 to 52164; and, the power gained bears the same proportion to the strength exerted: for when the handle has made one revolution, the wheel C D has made 10/69 of a revolution, and the screw _would have_ gone down 10/69 of a thread, or 10/69 of an inch: but in the same time the wheel E F has turned the _nut_ 10/70 of a revolution _in the same direction_; so that the latter has only gone down 10/69 less 10/70 of an inch; that is, (reducing to a common denominator) 700/4830 - 690/4830 = 10/4830 = 1/483 of an inch: Now to do this, the handle Q V has described a circle of three feet in diameter, or in round numbers 9 feet, or 108 inches; and to complete a descent of the screw of one thread, (or one inch) the handle must move through a space 483 times as great; that is, a space of 108 inches multiplied by 483 = 52164 inches: whence we see that the power gained is, as 52164 to 1: and reckoning a man’s strength at 150lbs. (exclusive of friction) that strength exhibits a pressure of _five millions two hundred and sixteen thousand four hundred pounds_; or upwards of _two thousand three hundred tons_: a result not unworthy to be mentioned with those of the hydraulic press; to which it might be still further assimilated by other proportions in the screw and nut wheels C D, E F. Adverting now, to the second property of this Machine: namely the simple power intended to act when the press is to be laden or discharged, the handle V should first be turned _backward_, until the cap W has slackened upon the goods; and the long pinions I K be raised by the mechanism X Y Z, which pinions, then geering only in the wheel C D, will raise the cap 1 inch for every turn of that wheel; or for every 69/10 turns of the handle V, say in round numbers for every seven turns: here then is a power of 756 to 1; very different from the former; yet produced by only a few inches motion of the long pinions I K.
We remark further, that the figure shews at G H _two_ of a system of friction rollers, destined to lessen the resistance which the turning-nut would otherwise oppose to the motion of the Machine. As to the friction between the screw itself and the nut--see a future article, in this _part_, tending to lessen or take away the friction of screws in general.
OF A PERISTALTIC MACHINE, _For raising much Water to small heights_.
Physicians will soonest understand the nature of this Machine, from the name I have given it. It is perhaps the most simple of Water-Machines; and certainly not the least efficient where it applies. It’s name is taken from the similarity of its action to the creeping of a worm, and to some of the functions of animal life. Yet it might be explained to the most unlettered housewife, when in the act of converting certain long vessels into _chitterlings_; or making room for the materials of a sausage or black pudding. To be serious: this Machine, in it’s simplest form, (see Plate 11) consists of a flexible tube C D, fig. 2, nailed to the ground, and connected with a short tube of metal containing two valves, A B, itself affixed to a box D, filled with water, or into which water flows. This water runs through the valve A, and distends the tube C D, on which rolls the body F, similar in form to a land roller. The Machine acts in the following manner: When the roller is drawn to the end D of the tube, the water fills the latter through the valve A; and on the roller’s return, this water is forced into the rising tube through the valve B.
The above is the simplest form of this mechanical trifle: But it has the disadvantage of an inconstant vibratory motion, not only of the water but the roller: which latter being heavy, would absorb considerable power. To remedy this evil, I have given the principle a rotatory form in fig. 1; where A B C is a spiral tube, duly fastened to the bottom of a shallow tub D E. At B is seen a conical roller, having the middle of the bottom of the tub for its summit and centre of gyration. The tube A B C, occupies rather more than one circumference; so that the cone presses during a small part of it’s revolution on both spires at once: by which means the Machine _would act_ without even one valve; though it is better to place one, _under_ the opening A. Now, observe the operation: as the cone rolls over the tube and round the common centre, in the direction of the arrow R the water enters behind it, through the opening A, (for the tub is plunged a few inches into the water) and is forced by it’s pressure into the ascending tube, which is a continuation of that, A B C. It would be superfluous to add, that these tubes are shewn in the figures _as cut open_, and presenting their inside to view; which representation is adopted in order to shew more completely the valves A and B of the 2d. figure.
An objection may occur to some, at sight of this Machine: namely, that the roller or cone B, would soon destroy the flexible tubes, by pressing too hard on their _puckered texture_. But to obviate this difficulty I have added, in fig. 3, a form of the tube (supposed of leather) which insures a proper _position_ of the leather under these rollers; accompanied by ledges A B, on which their surplus weight would bear, so as to annul every excess of pressure on the tube.
In many of the subjects I shall have to lay before my readers, the _forms_ are so numerous as to leave some difficulty in judging where the actual descriptions ought to end. This article itself, small as it is, offers an example of this: for I could draw several corollaries from the foregoing, that would offer new degrees of interest: but I am withheld by the apprehended want of room in the plates. I must at least defer my first intention, of _multiplying_ examples and shewing the influence of FORM on mechanical results in general. It will, however, always be open to me, to resume this subject when the principal object has been achieved--that of making known the principles of these inventions, with their most useful forms and properties. I observe, however, what has just occurred to me, that this Machine would be somewhat more _durable_, if the water-tube was pressed _between two rollers_, instead of being contracted from one side, by the action of a single one.
OF A DRAYMAN’S CANTER, _Or inclined Plane with increased Power_.
This Machine presents a simple method of increasing the power of the inclined plane, as used by carters or draymen for loading their carts; and called by them (in some counties) CANTERS. It admits of a gentle declivity in those planes: and thus considerably increases their power. The means consist in the transfer of the declivity from one end of the Machine to the other. Thus (plate 11, fig. 4) when the cask is rolled up from A to B, it is _wedged_ in that position by the wedge F; when _so much_ of its weight is supported by the feet C, (for all the feet are in pairs) that the end D of the Canter can be raised _with ease_ to E, so as to _re_-form the plane, in the direction of C E; at which time the feet D G drop into an upright position, and secure this new state of the plane. The cask is now rolled back from B to E, where it is found twice as _high_ as it was at B; and this manœuvre may be repeated several times according to the number of feet provided, and their length respectively. The _power_ of an inclined plane, is as its length to its height: and that power is doubled when the force is applied at the circumference of a cask or other rolling body. So that, here, the power being as 16 to 1, if a man can exert an energy of 200_lb._ the cask may weigh 3200_lb._ and still be raised with ease on this _Canter_, which therefore is three times as powerful as though the weight was raised directly from A to F in the usual method.
Should it be suggested, or thought, that this Machine applies only to _rolling_ bodies, I would just say that it might apply, cæteris paribus, as well to bodies sliding up the plane; or (using a small truck on the Machine) it might serve in a cotton warehouse, for piling the bags, &c. This System is doubtless susceptible of _discussion_, and may require to be modified for different purposes: but it is by no means devoid of practical capabilities.
OF A PERPETUAL WEDGE MACHINE, _Being a simple Method of gaining Power._
In Plate 12, fig. 5, let A B represent a wheel and axle, of which the wheel A is divided into 100 teeth; (more or less) and let C represent a second wheel with one tooth (or several) less than those of the first wheel A. These two wheels are concentric, for the axis of the wheel A, turns in the hollow centre of the wheel C; which latter wheel is fixed to the frame of the Machine, not here represented. D is a pinion that circulates round the wheel A and C in and along with the frame E as impelled by the hand acting on the handle F. Thus the circulating pinion is constantly occupied by means of its wedge formed teeth (of which one is shewn at D), in bringing the unequal teeth _a b_ of the wheels A and C _abreast of each other_: whence arises a _slow_ revolution of the wheel A, and of the axis B round the common centre. For if the number of the teeth on these wheels (A and C) differ only by unity or _one_, then must the handle D revolve one turn about that common centre to occasion 1/100 part of a revolution of the wheel A, and of course 100 turns to move the axis B once round that centre. And if further the wheel A be three times the diameter of the axis B, the power gained _there_ would be as 300 to 1, that is a power of 1_lb._ at a distance from the centre, _only_ equal to the radius of the wheel A, would countervail a weight of 300_lb._ suspended on the axis B: and supposing a man’s strength to be 100_lb._ he would raise (exclusive of friction) 30000_lb._ by this simple machine.
To shew more fully the essential properties of this Machine, I have represented only three teeth in all: one _b_ in the fixed wheel C; one a little smaller _a_, in the wheel A, (since this wheel has _more_ teeth than the former) and one D in the circulating pinion, whose form and manner of acting justifies in my apprehension, the name I have given to the Machine--a perpetual wedge Machine. I shall only add that there would equally be motion if the teeth of the wheel A instead of being more numerous than those of the wheel C were less numerous: but the manner of action would be different and I think less perfect.