Part 21

I therefore, say nothing more of this Instrument as a pendulum: but an inspection of the figure will shew, that it will not be useless as an ELIPSOGRAPH--which it clearly is, since the intersection of the bars _A D_ & _B C_; describes a true Ellipsis. It may be further shewn, that the ends of the moveable bar _C D_, are the vibrating _foci_ of a second ellipsis, like the first, which rolls under the other, so that the curve itself is _that_ which the centre of one ellipsis _a b c_ would describe, by rolling on the surface of another _e b d_. But, into these considerations I cannot now enter, as my “Century of Inventions” is fast becoming due, and time commands dispatch; I beg leave, therefore, to pass to the relation this subject seems to bear to a “Marine Level.”

It must, however, be premised, that I scarcely expect either of these methods to be correct enough for astronomical observations; as among other things, they have the _nautical top_ to contend with: but if I am fortunate enough to have suggested useful methods of procuring _relative_ stability on board a rolling ship, so as to suspend the better, a _nice_ instrument of astronomy; or so to counteract the restless ocean, as to assist the victims of sea-sickness, I shall not entirely have lost my labour.

My first idea on this subject, is the following: If we had on ship-board, a simple pendulum of several thousand feet high, it appears _certain_ that the oscillations of the ship would be begun and ended, before any single vibration could have been given to such a length of pendulum--which therefore, would scarcely vibrate at all: and if the natural _time_ of this compound pendulum (for we are not confined to these small dimensions) were made to be much longer than those of the ship _on it’s meta-centre_, this pendulum would scarcely vibrate at all: because it’s several tendencies to take motion from the ship, would extinguish each other before they had had time to produce any common effect.

Further, this result would probably be assisted by another property belonging to this mechanism: see fig. 4. This diagonal suspension, as repeated at _a b c d_, fig. 4, is of such a nature, that when it’s centres _a b_, are placed in any oblique position _e f_, (say by the rolling of a ship) the suspended bar _c d_, immediately takes a position of opposite obliquity _g h_, pointing _upward_ towards _i_, just as much as the line _e b_ points _downward_; while the middle line _k l_ remains level--whether caused by the slides _k l_, or the single slide _m_.

I dare not assert any thing respecting the form this principle should assume, in order to produce the most useful effects; but it appears that the principal _weight_ of the apparatus should be placed in the centre of gravity of the under bar _c d_. It would occur, of course, to every mechanician applying this System to real use, that in this fig. 4, we have only provided for one motion of the ship, the _rolling_ motion: and that, in consequence, this System should be suspended _in_ another similar one, acting longitudinally, so as to provide for the _pitching_ motions of the vessel. In a word, I confess, with regret, that I leave much _to do_, by way of bringing this idea to maturity--it being at this late hour, more than doubtful, whether I shall myself ever be able to resume the subject _at sea_, where alone it can be duly tried.

OF A SECOND ESSAY, _To procure a Marine Level_.

This would seem to be a simpler process than the former: but how far it may go beyond it in effect, I cannot say--having never had it in my power to _try_ either of these ideas on ship-board. I therefore merely present them to my readers, as themes for future thought and experiment.

Plate 45, fig. 5 represents this System--which is founded on the idea of deadening oscillatory motions at sea, by connecting the bodies to be thus _guarded_, with _a stream of flowing liquid_, the horizontal motions of which _must be_ subject to laws very different from those which rule vibrating bodies merely suspended.

The fluid used in this Machine (as oil, water, mercury, &c.) is to be pumped up by appropriate mechanism, from the vessel into which it flows at _x_, into a vessel placed a little above _z_; and to be let out by the cock _y_, through a kind of strainer _s_, of sufficient collective area to supply, with ease, the descending column _C_. The vessel and tube _C D_ are made as thin and light as possible: and the upper part, which is spherical, is inclosed in and suspended by the universal joint _a b c_, like those used to suspend other bodies, as a compass, &c. Moreover, the areas, at different heights, of the tube _C D_, are made in the inverse ratio of the velocities of the spouting fluid, at each given depth--so as to leave it but little tendency to press either outward or inward, while thus obeying the law of gravity. By these means, then, I think no vibrating motion will be excited in the falling column: but that the liquid will continue to flow perpendicularly, so as to preserve (nearly) the quietude of the vessel _C D_, and of any mirror or instrument it may be wished to keep in a given position, by connecting it with the perpendicular line thus obtained.

I repeat, however, that I know not how far these methods may go towards obtaining an artificial horizon, for astronomical uses. Indeed, I fear they will fall short in this respect--but I think them still worth trying, even for these--but especially for the purposes to which I have already alluded. And, if success crowns _this publication_, to the degree I am led to anticipate, I will not always leave so rich a question, in this doubtful predicament.

OF A FIRE-ESCAPE, _On a retarding Principle_.

This is a recollection from the specification of a Patent which I took out above thirty years ago, and in which I huddled together as many objects as a child would like to see in a box of play things. I perhaps acted, then, according to the _words_ of a French proverb--“abondance de bien ne nuit pas;” but in so doing, I fell into the charybdis of _another_ French proverb--“qui trop embrasse, mal étreint,” (a wide embrace cannot be a strong one) and in so doing, paved the way to much litigation--which happily did not occur.

The intention of this Machine, as represented in Plate 46, fig. 2, was to retard the fall of any _body_, or person, suspended to it, so as to prevent any concussion on reaching the ground. The means are brought to view in the perspective sketch given of the Machine. It is a kind of _jack_, inclosed in a case, and supposed to be laid carefully aside in the house represented in fig. 1 of this Plate. The Machine has a barrel, much like that of the jacks used for roasting; round which a rope is coiled, of sufficient length to reach the ground: and a wheel, connected with this barrel, works in an endless screw, which turns a shaft also like that of a common jack, but somewhat stronger; and finally, to this shaft is fixed a small cross piece, carrying, on pins, two weights _y z_, inclosed in the _fixed_ barrel _x_; by the centrifugal force of which enough friction is created, to prevent the acceleration of the falling body--whether a person or weight of any kind.

There is, moreover, a jib _a_, fig. 1, fixed between some, or all, the windows of the house whose inhabitants it is wished to guard from the danger of fire; this jib having the property, from the form of it’s foot, of taking by the suspension of any weight to it, a position perpendicular to the wall: Insomuch, that by the act of suspending the Machine to the jib--engaging the wrist in the noose _n_, and perhaps the foot in another loop of the same cord; a person may safely flee those dangers from fire, of which so many persons become the unhappy victims.

Since the 46th. Plate was engraved, it has occurred to me, that a method should have been shewn for raising the cord _n_, (fig. 2) after each descent. This operation might be performed by a handle put on the axis of the Machine, accompanied by a ratchet on the wheel, just like the similar parts of a jack for roasting. But, lest the inmates of a house on fire, should not have presence of mind enough to perform this operation, it might be better to have a spiral spring _in_ the Machine, to be _wound up_ by the descending body, and of force sufficient to raise again the cord after such descent.

OF A SECOND FIRE-ESCAPE, _By breaking the Fall_.

This Machine is also shewn in Plate 46, at fig. 1. It consists of a large truck, _A_, to be drawn rapidly to any _house on fire_, by one or more horses. The carriage or frame part _B B_, is an _open_ square frame _subtended_ by a first sheet of sack cloth, similar to the sacking of a bed: and on this are laid five, or more, _air mattrasses_ made of sack cloth, and varnished on the inside so as to be nearly air-tight; I say _nearly_ so, for it is _not_ intended they should form a spring capable of _returning_ any object thrown on them. On the contrary, each of the mattrasses has, at one or both ends, a valve 1, 2, &c. opening _outwards_, but kept closed by proper springs, so as to determine the pressure at which the air shall escape; that pressure being carefully graduated, so that the upper mattrass shall give way with ease, the second with greater effort, and the successive ones with progressive difficulty, until the under one remains totally closed, and stops the falling body altogether. By these means, if enough mattrasses are used, and they are _duly_ regulated, a person may jump from a house of three or four stories without incurring any danger. As to the length and breadth of this fire-escape, it should be ample enough to give the sufferers confidence to take the leap, and as small as an easy passage in the principal streets would require.

One thing must be described in _words_--as the mechanism to which it relates is fixed under the truck; and could not be seen in this perspective figure. These mattrasses are filled with air by an _horizontal air pump_, worked by a _crank_, which the axle itself of the hind wheels of the truck forms: whence, by pinning this axle to either of the hind wheels, the very motion of the carriage, as drawn by the horses, would distend the mattrasses--which would thus be ready for use the moment they arrived on the spot; and moreover, when there, this air could be replenished, after using, by turning this axle, through the wheels, _by hand cranks slipped on it’s ends_ at the place of the linch-pins. Or, in fine, this operation might be performed by an air pump prepared for it alone, and placed in any convenient part of the Machine.

OF A ROTATORY CHOCOLATE MILL.

Figures 1 & 2 of Plate 47, exhibit this Machine. It is, merely, an attempt to effect, by power and a rotatory motion, what is done by hand and a vibrating one. To understand this latter, my readers (who have not seen chocolate made) will suppose a metallic rolling-pin, but cylindrical held in both hands, and moved parallel to itself, over a slab of marble, to and from the person employed; who holds the instrument _fast_ when pushing it from him, and suffers it to turn _a little_ every time he draws it towards him. He thus presents, sometime or other, every particle of the chocolate to every part of the slab and the roller: and this is also done by the Machine shewn in Plate 47. In figs. 1 and 2, _A_ represents a cylinder of stone or metal, used instead of the aforesaid slab; and _B_ a cylinder answering to the roller in question. The latter is placed, by it’s axis, on two forks _a b_, so as to lean, by it’s weight, obliquely against the cylinder _A_, which it does less or more heavily as the forks, or stands _a b_, are placed nearer or farther off from the general centre. Further, the motions of these two rollers _A_ and _B_, are connected by two equal (or nearly equal) wheels _c d_, by which, when _A_ is turned, _B_ turns also; but so as to give the surface of the latter _much less_ velocity than that of _A_, though in the same direction. By these means, all the matter adhering to both cylinders (for chocolate is made in an unctuous state) is at one time or another, brought into intimate union, and ground together; and thus is the usual problem resolved, on rotatory principles: nor need we mention the several scrapers, &c. that would be applied to gather up the paste to the middle of the rollers, when spread abroad by the grinding process.

It may not be useless, just to say here, that this is likewise a good mill for grinding paint or oil colours.

OF A ROTATORY MANGLE.

I have insisted, often, on the propriety, mechanically speaking, of doing every thing by rotatory motion; and thus of avoiding oscillation wherever it is possible. The present Mangle is another attempt to employ that principle. In Plate 47, figs. 3 and 4, is an under cylinder, turned as usual by any convenient _power_. _B_ is a small cylinder not connected with it, nor touching it, being intended merely to receive the weight of the mangle-cylinder _D_, with the _goods_ rolled on it. _C_ is an upper cylinder as heavy as necessary, or loaden through it’s _journals_ or centres, with sufficient weights to make it so. Again, the motions of the two cylinders _A_ and _C_, take place in such a direction, that any round body placed and pressed between them, would receive from them the same motion; and thus, a roller of goods, there introduced, will be _mangled_. This process is so performed, because the cylinders have toothed wheels _a_, _b_, on their axes, but which do _not_ geer together: These wheels being connected by an intermediate wheel _c_, which makes them concur in producing the rolling effect above mentioned. But, one thing remains to be observed: the wheels _a b_, though drawn apparently equal, are not equal. The upper one _a_, has a tooth or two _more_ than the under--so that the motion to the right hand of the under surface of that cylinder, is not equal to the opposite motion of the cylinder _A_. And hence, the cloth roller _D_, progresses from _D_ towards _x_, between the cylinders _A C_, and finally falls out at _x_, after as many turns of the whole, as the wheels _A C_ have been calculated to give; and this, is according to the degree of mangling required.

OF A MACHINE, _For driving the_ SHUTTLE _of_ POWER LOOMS.

It is too late to bring this Machine into what might almost be called an overstocked market of ingenuity--since many power Looms exist, work, and seem to want nothing to make them perfect. But an idea of _forty years_ standing, founded on a principle worthy of attention then, may perhaps not be altogether vain at present: Besides--I have engaged in my prospectus to present it to the public. I could, indeed, enter into other parts of the Power Loom--which I had then begun to execute; but such is the rapidity with which that Machine is now _striding_ to perfection, that it would be superfluous. I merely then, fulfil my promise.

On the afore-mentioned occasion, I thought it of importance, that the force employed to throw the shuttle, should be capable of being regulated to any and every degree: and especially should be fully _prepared_ to act, _before_ it’s action began: and should, then, act independently of every other impulse.

In fig. 1 of Plate 48, _A_ is a wheel or pulley of about six inches in diameter, from which two cords proceed in opposite directions (_B C_) to the _pickers_, which drive the shuttles _D E_ in the usual method. This pulley runs on an axis going through the bottom of the lathe, (or beater) and it _might_ have a crank, behind, of a radius equal to _a b_: but to shew the whole in one figure, I suppose the following mechanism to be placed in the front of the lathe, and just _before_ the face of this wheel or pulley _A_. _c d_ is a bar turning on the centre _c_, and receiving at it’s other end the pressure of a spring _e d_, which in it’s turn, is susceptible of different degrees of springiness, as regulated by the screw _f_. On a stud _i_ in the wheel _A_, is put the small bar _i d_, which forms also a turning joint in the bar _c d_: and thus communicates the effort of the spring to the stud _i_, and thence to the wheel _A_. Finally, this wheel has either under it, on the front side of the lathe, or on it’s axis, at the back, a pulley, by which it can be turned, by means of one or other of the cords brought from the _breast beam_ of the loom, round the pullies _x_ and _y_, to this wheel _a b i_, according to the dotted lines. Supposing then, _one_ of these cords to be tightened by the backward motion of the lathe, it will draw the wheel _A_ about half round: when the stud _i_ will rise to the point _b_, straining the spring to get over the centre: and as soon as it _is_ over, the spring will _act_, and drive the picker and the shuttle with the desired speed, independently of any other _mover_. And it is evident, that now the opposite cord _x_ or _y_, will be tightened so that when the lathe shall be again pushed backward to form the opening for the shuttle the slide will be carried back over the centre _a_, and re-produce another impulse in a contrary direction.

OF AN AIR PUMP, _Or_ ESSAY _towards completing the Vacuum_.

The rapidity with which a vacuum is formed by an Air Pump, depends on the _ratio_ between the contents of the receiver and those of the pump barrels. If the latter be just equal to the contents of the former, (which is a _very_ large proportion) the exhaustion will follow this series:--there will _remain_ in the receiver after each stroke, the first contents being 1, 1/2, 1/4, 1/8, 1/16, 1/32, 1/64, 1/128, 1/256, &c. But if the pump barrel contains _twice_ the volume of the receiver--then the remaining air, after the strokes, will be 1/3, 1/9, 1/27, 1/81, 1/243, 1/729, 1/2187, 1/6561, &c. being much nearer to a vacuum than on the former supposition.

To meet this case, then, I have thought a water pump might be used: that is, a barrel or vessel, _much_ larger than the receiver; and which by the action of a smaller pump, placed on a lower level, might be alternately filled with water and emptied so as in a few operations to complete the exhaustion, very nearly.

Thus, in fig. 2 of Plate 48, _A_ is a receiver, _B_ is a large vessel that can be filled with water from the tub _C_ below; and _D_ is the pump, worked by the handle _E_. It is a common water pump, (so much the readier adopted, as requiring _little_ care in the execution.) The question was to make this pump alternately _fill_ and _empty_ the vessel _B_. Adverting first to the _filling_, _a c_ are two cocks, having each a side-passage for the water; and these passages are _now_ so placed, as by working the pump we suck water out of the tub _C_, and throw it into the vessel _B_, through the valve _b_;--by which means all its air is driven out through the lateral valve _e_. When this is done, the cocks _c d_ (which are so made as to be worked by the same _mover_) are turned into a new position, which opens the pipe _p_ to the pump _D_, and _that_ _q_ to the returning spout _r_; by which means the water is drawn _from_ the vessel _B_, and thrown into the tub _C_: so that the air is again drawn out of the receiver _A_, through the inverted valve _s_, into the vessel _B_, and another degree of exhaustion occasioned. This being done, the cocks are again put into their present position; the air expelled by the water through the valve _e_ as before, and a new stroke prepared. It is scarcely needful to add, that if the vessel _B_ contained ten times as much volume as the receiver _A_, the exhaustion of the latter at each emptying of the vessel _B_ would follow this ratio--1/11, 1/121, 1/1331, &c. thus approaching by rapid degrees to a perfect vacuum. The water, or liquid, used for this purpose would of course be as perfectly purged of air, as possible.

OF AN INCLINED WATER WHEEL.

The principal mechanical merit I conceive this Machine to possess, lies in the facility it gives of taking a stream of water as _high_, and discharging it as _low_ as possible: and both nearly in the direction in which it naturally flows. Of the advantage it possesses in keeping the water a long time from falling, I shall not now speak, as it would require more discussion than this work comports; and, moreover, the Plate confines us to a somewhat contracted representation, which I hope my readers will excuse.

Plate 48 fig. 3, _A B_ is the section of the wheel, and _C D_ a small portion of it’s circumference--which shews the form and position of the floats _a b c_, &c. _E_ is a floor on which the upper water flows, and from which it falls thinly on to the wheel--whose motion is purposely made as slow as possible. The water then, occupies one half of the wheel’s circumference, falls by a gentle slope and finally leaves the wheel at _d_, whether it there touches the lower water, or not. This wheel is allowed to be incapable of _using_ to advantage a large stream of water--but is doubtless fit to employ a small stream, _in the best manner_.

OF A VESSEL, _To assist in taking Medicine, &c._

I have hesitated a moment to describe this method of helping the weak, in body or mind, to conquer their aversion to medicine--several persons having threatened me with a larger dose of ridicule than I am prepared to swallow. But surely, if we can only conquer a child’s timidity, so as to induce him to take, speedily, what his health requires, we shall not do a thing altogether laughable. We shall, perhaps, preserve a beloved child to the solicitude of a mother! and perhaps--a citizen to his country! If then, some laugh, _more_ will approve; and I therefore continue the promised article.

Fig. 4 of Plate 48, shews this cup, composed of an inner and an outer vessel: the first to hold the medicine, and the latter a little tea, or other proper liquid to wash it down. The cups have a spout common to both; but the outer cup retains it’s contents as long as the small funnel _a_, is stopped with the thumb or finger. Thus then, the medicine is first taken, while the liquid is retained in the outer vessel--but the thumb being removed, the liquid also flows into the mouth, and in a good measure removes the taste it was wished to disguise.

OF AN AERO-HYDRAULIC MACHINE, _For raising Water in large quantities_.

The art of constructing Mills, or Machines to be driven by the wind, is so well known, that the results are considered as being, very nearly, what a perfect theory would require. It is, therefore, no part of my purpose to discuss either the theory or practice of that art. But I think _that a still wider grasp may be taken of this powerful agent_, so as to secure a further degree of utility, even while following less closely the abstract principles of mechanical philosophy. I enter then, directly, on the description of another of my _wind Machines_, in order to give an idea of the means I contemplate for _losing_ the importance of those details in the magnitude of the general effect.