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ART. 8. NEW INVENTION.

spent on board to propel it through water, than would give it an equal velocity if applied from the shore, the necessity for the excess must proceed, not from any imperfection in the engine, but from circumstances connected with the machi

On the Propulsion of Navigable Bodies. TH HE important and increasing benefits this great country experiences from its improvements in nautical mechanism, and the extraordinary magnitude of the vessels actuated by mechanical power, are circumstances that infal-nery, actuated by it as a “primum molibly excite the attention of an European bile," and the medium (i. e. water) upon on his arrival in the United States. The which it operates. Brooklyn steam-ferry-boat was the first moving object that arrested my attention as I entered the port of New-York. The effect, to me who had never witnessed the spontaneous march of the huge fabric, laden with carriages, horses and men, now gliding past our ship, was delightful, and impressed upon my imagination a more elevated idea of the enterprising spirit of the New World, than would the most lofty panegyric, unaccompanied by the test before me.

Thus forcibly impressed, before I had even touched the American shores, an habitual fondness for investigation, has subsequently impelled me to study the progressive history of mechanical navigation, from the obscure hints of the first projectors of the steam-engine, to the more finished works of Fulton. In the course of my pursuits, the latent principles of action were developed, and it became obvious that, notwithstanding the excellence already attained, the machine was still imperfect-imperfect in its original principle, and that there yet remained a wide unlocated field for the introduction of important improvements.

Comparing the magnitude of vessels with the power ordinarily expended in their propulsion, there seemed to be a great disparity, and the fact became indisputable, when I reflected, that, on the canals in England, barges carrying thirty tons, and themselves weighing at least fifteen tons, making a total gravity of forty-five tons, (measured by the displacement of water), are towed, through still water, five miles per hour by one horse. But here the Brooklyn twin ferry-boat, each half being shaped like the English canal barges, displaces only four times the bulk of water, (i. e. 180 tons,) and yet advances but five and a half miles per hour through the water, her engine exerting a power equal to that of twentyfour horses.

Now it is manifest that the power of a steam-engine must be the same, whether exerted on board a vessel or on shore; and, therefore, if a greater power be VOL. III.-No. н. 17

That power is unavoidably lost in the friction of the wheels giving motion to the water-wheel is obvious, and some allowance must be made on that account, but the amount of that loss bears but a small proportion to the total deficiency—the remainder must therefore be attributable to other causes which I will endeavour to point out.

Let us for a moment suppose the two vessels forming the Nassau ferry-boat, to float, connectedly as they now do, but each in a separate canal, divided by a firm bank, and that the water-wheel, instead of acting against water, rolled upon solid ground, as quickly as it now turns, (i. e. 20 times per minute,) the result would be an advance of the boat, as rapid as the revolution of the wheel, which, taking its actual measurement of 12-6 diameter, would give a pace of nine miles per hour. But we find by experience, that although the water-wheel of this boat does actually revolve at the rate of nine miles per hour, the boat never advances through the water, more than five and a half miles. Whence this enormous deficiency?

The paddles of water-wheels impinge upon unsolid måtter, that yields to the stroke, and one-third of their velocity is spent in agitating the water into which they dip: thus, every three feet of the wheels' motions imparts two to the boat, and one in opposite course to the water. The powers thus expended, in producing these opposite motions, are, as the squares of their velocities, and, therefore, onefifth of the primum mobile, is thus lost to every useful purpose.

To illustrate this position more sensibly, let us again imagine the vessel placed in the double canal, above instanced, but that the dividing bank, upon which the wheel rolls, consists of loose sand, instead of hard ground, the sand will then slip back with the wheel, and inasmuch as it does slip back, so much will the motion of the boat be less than that of the wheel. The effect in water is similar, except that water, consisting of more minute, smooth

er, and less tenacious particles, gives way more easily than would the sand just instanced, the loss of power would therefore be still greater when the wheel operated in water as at present.

Having now accounted for the loss of one-fifth of the whole power of the primum mobile, let us proceed to consider the effect of the obliquity with which the paddles of common water-wheels pass through the water.

The force of an impinging paddle, like all other oblique forces, is resolvable into two forces, one horizontal, the other perpendicular of these, the horizontal is calculated to propel horizontally, the perpendicular, to operate perpendicularly.It must be obvious that the horizontal force can alone promote the progress of a boat, the perpendicular exerted upwards and downwards by the opposite paddles of water-wheels, being utterly indifferent to horizontal progression. It will not therefore be correct to say the perpendicular force operates against, or in counteraction of the progressive power, because, being at right angles to it, it cannot oppose horizontal propulsion.-It should rather be viewed, as in fact it is, a serious burthen constantly balancing, and in effect subtracting a part of the force of the primum mobile, without any other result than to keep up a continual agitation of the water, and strain upon the machinery, and that if freed from the resistance thus uselessly sacrificing a portion of its power, the primum mobile will immediately be adequate to actuate a wheel of greater dimensions than at present, and carrying paddles of any constructable dimensions. These enlarged paddles will revolve faster, and be more firmly resisted by the water, and the boat will advance with increased rapidity.

The comparative value of horizontal force propelling the boat, and of the perpendicular effort in any position of a paddle, may be found by dropping a line from the upper edge or from the level of immersion, if it be not wholly under water, and by drawing another line horizontally from the lower edge until it intersects the perpendicular line, thus forming a right angled triangle, of which the paddle's edge is the hypothenuse. The square of the perpendicular line, measured from the upper part of the paddle or level of immersion, as the case may be, to the point of intersection, will represent the horizontal or propulsive force, and the square of the horizontal line, measured from the same point to the extremity of the paddle, the perpendicular force: the squares of

these two lines being equal to that of the paddle's edge, or third side of the triangle, representing the whole force. It results from many wheels thus tested, that the loss of power from this cause alone is never less than one-sixth of the whole primum mobile.

It must, however, be understood that this result is obtained on the assumption that the paddle is resisted equably during its whole passage through the water, which really is not the fact.-The greater part of its power being expended at the instant of impact, and before the vis-inertia of the water has been entirely overcome. But, at the instant of impinging, the paddles are inclined in an angle of 45° nearly, where, upon the principle already developed, half their power is lost perpendicularly-any remaining power being scarcely more than sufficient to counteract the perpendicular resistance occasioned by the gravity of the water lifted by the emerging paddles. I therefore estimate the total loss of power, from perpendicular resistance, at one half the primum mobile.

But there is another circumstance creating a considerable loss of power, which as it is less obvious, so is it the more necessary to be particular in explaining its nature.

Every person who has travelled in a steam-boat must have noticed that, as each paddle of the water-wheel comes in contact with the water, an universal vibration prevails through the vessel. Let us imagine this effect did not occur, but that it was desired to produce it—would it not require a great extra exertion of power? and if it require a great extra exertion of power to produce it, if desired, must not its existence when deprecated, be accompanied with an expense of power that is worse than useless? But in what part of the apparatus does this loss take place?-the water-wheel.-Suppose, for sake of argument, the materials of the water-wheel and other parts moving in conjunction, are constructed to be nearly devoid of weight, they would also be nearly devoid of vis-inertiæ, as each paddle met the water, the wheel's motion would be almost annihilated by the force of the concussion, which would then bear an immense proportion to the vis-inertia, as with an oar falling flatwise on water. It would afterward, gradually recover and proceed with accelerated velocity, till another paddle striking impeded it as before, and so on successively, the wheel moving constantly by starts; make the wheel heavier and its vis-inertia be

ing increased, the retardation will be diminished,-add again to its weight, and a farther reduction will take place; thus, as the wheel becomes more ponderous its motion becomes more equable, but yet can never be quite equable, and the retardations of its motion, though not suceptible of ocular demonstration, exist, and require to be constantly compensated by borrowing from the vis-inertia of the component materials, a power which it is necessary, as constantly to re-supply by subtracting from the power of the primum mobile. The loss of force thus caused, it is difficult, perhaps impossible to ascertain with precision; but when we reflect that it occurs eight times to every revolution of the wheel, it must be considerable. As it is necessary in the present instance to give it some value, I assume, one-twelfth of the primum mobile; but in case of rapid motion, apprehend it becomes much more considerable.

If then this loss of power be added to that proceeding from perpendicular resistance, and to that already shown to arise from the unsolid nature of the matter upon which the paddles operate, it will appear that at least three-fourths of the whole power expended by the primum mobile, is to every useful end exerted in vain. Let us, therefore, suppose a proportionate subtraction from the power of the engine of the Brooklyn ferry-boat, and the remainder equal to that of six horses, to be applied directly without waste, as in towing from land, the boat will then make the same progress as at present; and that result, making due allowance for the additional velocity of half a mile imparted to the boat, will nearly accord with the effects manifested in the canals in England.

Having shown from what causes arise the losses of power in propelling boats by mechanism, as now applied, let us inquire how far it is possible to remedy these inconveniences.

The loss of power proceeding from perpendicular resistance was, I am informed, a circumstance that seriously weighed upon the mind of Mr. Fulton; but being unacquainted with any feasible contrivance for preventing it, he had recourse to the costly expedient of employing engines of such immense powers as, that after submitting to every loss, the remainder, not exceeding one-fourth of the original force, was still sufficient to produce a satisfactory result.

Can any reasonable person imagine the power of eighty horses, applied from the land, would be necessary to pro

pel the boat "Chancellor Livingston," or seventy-five the " Paragon?" But, notwithstanding the enormous sacrifice, Mr. Fulton reduced to its minimum the inconvenience of a system radically defective.

The obvious loss of power, as above explained, was the first circumstance that excited my attention, and I endeavoured to prevent it by contriving a water-wheel with upright paddles, upon a new and simple construction. On putting this wheel in operation on board the York ferry-boat, with paddles of as great surface as those of the old wheel, her speed was increased about one-tenth, but the engine then made nineteen strokes per minute, being four more than with the old wheel. This circumstance proved that the upright paddles were not so firmly resisted by the water as the oblique, an effect not unexpected, but more considerable than I had anticipated. This, on reflection, I found to proceed from the fact, that after starting, the stream projected behind the wheel was constantly driven horizontally in the direction of that already created, and which, of course, presented an insufficient resistance, while the operation of the common wheel in that part of its journey where the greatest effect is produced, is not attended with that particular inconvenience. This evil may, however, be obviated by making the upright paddles of such ample dimensions as to bear against a very great section of water, an expedient that may not always be convenient. Thus, excepting that the wheel operated admirably among ice, little was effected where I had expected much, and I began to suspect a fundamental error in the ordinary application of the primum mobile.

Convinced from the facts and reasonings already developed, that the great waste of power was solely connected with the operation upon the water, I resolved to persevere, and made a variety of experiments to ascertain the effects of placing the water-wheel within a horizontal trough, open at each end, but enclosed at the sides and bottom, making, occasionally, various apertures therein. The effects were curious, but unattended with profitable result, except that of leading me ultimately to reject the immediate use of power, and inducing the contemplation of a negative application, which is astonishing in its effects, and opens a new era in one of the most important arts yet practised by mankind.

It would be impossible for me to detail the successive gradations of idea that led

to the conception of a discovery, great in its consequences. Impeded by mental inertia, it came slowly at first, and with reluctance, but when once in motion, it rushed forward with the accelerated impetus of truth, and carried conviction before it.

Every attempt, not excepting my own, has heretofore been made on a false basis, namely, that of operating upon the water with a view to benefit from the resistance of its inertia. The only advantageous method is to reverse the system, and to make the water-wheel revolve within a raceway, fitting it closely on each side and beneath, and rising behind it to the surface of the water, the forward end closed above so as to convert it into a tube, the whole being made to extend some feet before and behind the wheel.

Now, if this raceway were enclosed at the forward extremity, it would be not unlike a boat. Let it be imagined, for illustration, that by some means (no matter what) a boat be so circumstanced that the water, in which it is immersed, does not press against the head, will not the natural pressure of the water astern produce forward motion? Suppose the raceway, above described, to be a boat-the water within it, when all is quiescent, resists the pressure of the external water ahead-put the wheel in motion, and the water contained in the raceway is expelled at an expense of power, equal to the lateral pressure of a column of water, of its own height. The pressure of the water, thus expelled, against the inclined part of the raceway, and of the waterwheel against that water, are equal and opposite, and therefore (the water-wheel and raceway being both fixed to the boat) indifferent to motion. But let us now look to the external water, and we shall perceive that, by the removal of the water within the raceway, the external resist ance to the raceway has been entirely removed, while the external pressure, he neath the inclined plane of the causeway, remains unimpaired, and urges it forward with the lateral pressure of a column of water of its own height, and does actually propel the raceway, and with it the boat. The forward internal water would, however, be disposed from gravity to fall backward under the wheel, when the wheel had removed the water beneath itself, but the forward end of the raceway being converted into a tube, the vis-inertia of the included water, at some little distance in advance of the wheel, operates for a moment, in complete counteraction of the gravity of that in its immediate contiguity,

because a separation of waters cannot take place without the creation of a vacuum, thus the water is for a moment sustained by atmospheric pressure, and cannot instantly fall under the wheel, as it would, were the raceway open above. But the pressure of the external water, beneath the inclined part of the raceway, is in perpetual action, and, before the vis-inertia, above mentioned, can be overcome, has propelled the raceway into other water, whose vis-inertiæ has also to be overcome, and so on ad infinitum. Thus the pressure of the external water is always in action beneath the inclined end of the causeway, while at the other extremity, its resistance is in perpetual suspension. By this arrangement it is obvious that the power gained, is equal to the power spent, both being measured by columns of water of equal altitude, and, consequently, that the effect resulting from force thus exerted on board a vessel to propel it, must be equal to that proceeding from an equal exertion from the land, an object hitherto deemed unattainable.

Under this system, the application of my water-wheel is useful and important; the object now is to remove the water from within the raceway as freely as possible. The common wheel, though not equally advantageous, may, however, be employed with diminished inconvenience, it does not require to be so deeply immersed, as heretofore, in the water to which it is opposed.

From this explanation it is obvious that the machinery is not to be applied to produce the propulsive power, but merely to remove the natural resistance to a natural pressure, already existing, and disposed by nature to be active. The oblique part of the raceway will admit of an almost infinite variety of shapes. The whole may even be included within the bulk of the vessel, provided its obliquity be preserved; for the action of the water-wheel will then reduce the resistance ahead, while the pressure astern remaining undiminished, motion must ensue, with a power equal to the difference: and it has been merely from the omission of this obliquity, which would, to appearance, obstruct progression, that all who have hitherto attempted to propel vessels, by forcing water through tubes from stem to stern, have not succeeded in their endeavours.

I conclude with an explanatory diagram of the discovery, and when clearly understood, court public investigation.

C. A. BUSBY, No. 2 Law Buildings. New-York, May 20, 1818.

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negative and inverted use of the principle of the overshot wheel, and possessing all its advantages.

In the Philosophical Transactions, vol. li. for the year 1759, there is a paper, by the celebrated Mr. Smeaton, with experiments on mills; from these experiments it appears (p. 129) that the effect obtained by the overshot wheel, is frequently four and five times as great as with the undershot wheel, in the same time, and with equal expenditures of power. The great Dr. Franklin was correct when, in his Essay, read before the Philosophical Society of Philadelphia, he maintained that wheels, operating as at present, could not be used to any advantage. We are also informed by Mr. Fulton, that, in 1806, the late lord Stanhope assured him, in London, that a boat could not be successfully constructed on the principles and combinations now in use; for can they be said to be employed successfully or advantageously, when, through their inefficient agency, threefourths of the primum mobile is sacrificed? C. A. B.

ART. 9. LITERARY AND PHILOSOPHICAL INTELLIGENCE. Tis announced that Dr. Rees' New Cyclopædia will be completed within the present year.

IT

KOTZEBUE, the celebrated German dra

matic writer, has just published a collection of Tales addressed to his Sons. They will soon appear both in French and English.

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