The inventor expected the operation of his device to be as follows: "A" is a large magnet, elevated on a short pillar at the foot of which is a straight inclined tube, "C" "F" the ends of which are connected with a curved or semicircular tube "C", "D", "E", "F", as shown in the figure.
The weight at the lower extremity is supposedto ascend through the curved tube by the attraction of the magnet "A" and upon reaching the point "C" the supposition was that upon passing the point "C" the attraction of the magnet "A" would be sufficient to hold it there * * * back to the point "F" through the straight tube, and then be drawn by the magnet through the curved tube to the point "C" and so on perpetually.
The impracticability of the above device is manifest. At a point between "D" and "E" it is plain the ball would have to ascend perpendicularly and if the magnet exerts sufficient attraction to elevate the weight at that point it would surely hold the weight at the point "C", for at "C" the weight would be much nearer the magnet and consequently much more strongly attracted.
In the same work by Gaspar Schott from which an account of the preceding device is obtained he gives an account of the device of Dr. Jacobus.
Dr. Jacobus's scheme is illustrated by the following figure:
It will be observed that the above figure shows a string of iron balls "A" suspended on a grooved wheel "E" on an axle "C" between two uprights "FF". At "H" lies a large lodestone,which is to attract the balls at "D" and was expected by the inventor to cause the wheel to rotate.
In 1864, Johann Ernst Friedrich Ludeke, of London, and Daniel Wilckens, of Surrey, applied for British patent on "Improvements in Motive Power by Capillary Attraction." They describe their invention as follows:
Our invention consists of improvements in motive power by capillary attraction constructed as follows:Figure 1 of the accompanying drawings represents in horizontal section a square case or cistern; this cistern is filled with water nearly to the top, and two wheels markeda,a, andb,b, are placed in the water in the cistern. By capillary attraction the water rises between the two wheels markedx,x, to a height above the level of thewater in proportion to the distance of the wheels from each other atx,x. As the water rises between the wheels markedx,x, above its level, the weight of water between the wheels atx,x, will cause the wheels to continually revolve.Figure 2 represents the same as Figure 1, but in a vertical section. The said power may be obtained by wheels moved on axis, or by other apparatus by rise and fall in the water by vertical motion.
Our invention consists of improvements in motive power by capillary attraction constructed as follows:
Figure 1 of the accompanying drawings represents in horizontal section a square case or cistern; this cistern is filled with water nearly to the top, and two wheels markeda,a, andb,b, are placed in the water in the cistern. By capillary attraction the water rises between the two wheels markedx,x, to a height above the level of thewater in proportion to the distance of the wheels from each other atx,x. As the water rises between the wheels markedx,x, above its level, the weight of water between the wheels atx,x, will cause the wheels to continually revolve.
Figure 2 represents the same as Figure 1, but in a vertical section. The said power may be obtained by wheels moved on axis, or by other apparatus by rise and fall in the water by vertical motion.
The device which we have designated "The Jurin Device," was not, in fact, invented by Jurin. James Jurin furnished an account of the invention to The Royal Society of London, and it appears in the reports of that society published in 1720. The invention was by a friend of Jurin's whose name he does not give in the account.
Jurin's account of his friend's invention is as follows:
Some days ago a method was proposed to me by an ingenious friend for making a perpetual motion, which seemed so plausible, and indeed so easily demonstrable from an observation of the late Mr. Hawksbee, said to be grounded upon experiment, that though I am far from having any opinion of attempts of this nature, yet, I confess, I could not see why it should not succeed. Upon trial indeed I found myself disappointed. But as searches after things impossible in themselves are frequently observed to produce other discoveries,unexpected by the Inventor; so this Proposal has given occasion not only to rectify some mistakes into which we had been led, by that ingenious and useful member of the Royal Society above named, but likewise to detect the real principle, by which water is raised and suspended in capillary tubes, above the level.My friend's proposal was as follows:Fig. 1. Let A B C be a capillary siphon, composed of two legs A B, B C, unequal both in length and diameter; whose longer and narrower leg A B having its orifice A immersed in water, the water will rise above the level, till it fills the whole tube A B, and will then continue suspended. If the wider and shorter leg B C, be in like manner immersed, the water will only rise to same height as F C, less than the entire height of the tube B C.This siphon being filled with water and the orifice A sunk below the surface of the water D E, my friend reasons thus:Since the two columns of water A B and F C, by the supposition, will be suspended by some power acting within the tubes they are contained in, they cannot determine the water to move one way, or the other. But the column B F, having nothing to support it, must descend, and cause the water to run out at C. Then the pressure of the atmosphere driving the water upward through the orifice A, to supply the vacuity, which would otherwise be left in the upper part of the tube B C, this must necessarily produce a perpetual motion,since the water runs into the same vessel, out of which it rises. But the fallacy of this reasoning appears upon making the experiment.Exp. 1. For the water, instead of running out at the orifice C rises upwards towards F, and running all out of the leg B C, remains suspended in the other leg to the height A B.Exp. 2. The same thing succeeds upon taking the siphon out of the water, into which its lower orifice A had been immersed, the water then falling in drops out of the orifice A, and standing at last at the height A B. But in making these two experiments it is necessary that A G the difference of the legs exceed F C, otherwise the water will not run either way.Exp. 3. Upon inverting the siphon full of water, it continues without motion either way.The reason of all which will plainly appear, when we come to discover the principle, by which the water is suspended in capillary tubes.Mr. Hawksbee's observation is as follows:Fig. 2. Let A B F C be a capillary siphon, into which the water will rise above the level to the height C F, and let B A be the depth of the orifice of its longer leg below the surface of the water D E. Then the siphon being filled with water, if B A be not greater than C F, the water will not run out at A, but will remain suspended.This seems indeed very plausible at first sight. For since the column of water F C will be suspended by some power within the tube, why should not the column B A, being equal to, or lessthan the former, continue suspended by the same power.Exp. 4. In fact, if the orifice C be lifted up out of the water D E, the water in the tube will continue suspended, unless B A exceed F C.Exp. 5. But when C is never so little immersed in the water immediately the water in the tube runs out in drops at the orifice A, though the length A B be considerably less than the height C F.Mr. Hawksbee, in his book of Experiments, has advanced another observation, namely, that the shorter leg of a capillary siphon, as A B F C, must be immersed in the water to the depth F C, which is equal to the height of the column, that would be suspended in it, before the water will run out of the longer leg.Exp. 6. From what mistake this has proceeded, I cannot imagine; for the water runs out at the longer leg, as soon as the orifice of the shorter leg comes to touch the surface of the stagnant water, without being at all immersed therein.
Some days ago a method was proposed to me by an ingenious friend for making a perpetual motion, which seemed so plausible, and indeed so easily demonstrable from an observation of the late Mr. Hawksbee, said to be grounded upon experiment, that though I am far from having any opinion of attempts of this nature, yet, I confess, I could not see why it should not succeed. Upon trial indeed I found myself disappointed. But as searches after things impossible in themselves are frequently observed to produce other discoveries,unexpected by the Inventor; so this Proposal has given occasion not only to rectify some mistakes into which we had been led, by that ingenious and useful member of the Royal Society above named, but likewise to detect the real principle, by which water is raised and suspended in capillary tubes, above the level.
My friend's proposal was as follows:
Fig. 1. Let A B C be a capillary siphon, composed of two legs A B, B C, unequal both in length and diameter; whose longer and narrower leg A B having its orifice A immersed in water, the water will rise above the level, till it fills the whole tube A B, and will then continue suspended. If the wider and shorter leg B C, be in like manner immersed, the water will only rise to same height as F C, less than the entire height of the tube B C.
This siphon being filled with water and the orifice A sunk below the surface of the water D E, my friend reasons thus:
Since the two columns of water A B and F C, by the supposition, will be suspended by some power acting within the tubes they are contained in, they cannot determine the water to move one way, or the other. But the column B F, having nothing to support it, must descend, and cause the water to run out at C. Then the pressure of the atmosphere driving the water upward through the orifice A, to supply the vacuity, which would otherwise be left in the upper part of the tube B C, this must necessarily produce a perpetual motion,since the water runs into the same vessel, out of which it rises. But the fallacy of this reasoning appears upon making the experiment.
Exp. 1. For the water, instead of running out at the orifice C rises upwards towards F, and running all out of the leg B C, remains suspended in the other leg to the height A B.
Exp. 2. The same thing succeeds upon taking the siphon out of the water, into which its lower orifice A had been immersed, the water then falling in drops out of the orifice A, and standing at last at the height A B. But in making these two experiments it is necessary that A G the difference of the legs exceed F C, otherwise the water will not run either way.
Exp. 3. Upon inverting the siphon full of water, it continues without motion either way.
The reason of all which will plainly appear, when we come to discover the principle, by which the water is suspended in capillary tubes.
Mr. Hawksbee's observation is as follows:
Fig. 2. Let A B F C be a capillary siphon, into which the water will rise above the level to the height C F, and let B A be the depth of the orifice of its longer leg below the surface of the water D E. Then the siphon being filled with water, if B A be not greater than C F, the water will not run out at A, but will remain suspended.
This seems indeed very plausible at first sight. For since the column of water F C will be suspended by some power within the tube, why should not the column B A, being equal to, or lessthan the former, continue suspended by the same power.
Exp. 4. In fact, if the orifice C be lifted up out of the water D E, the water in the tube will continue suspended, unless B A exceed F C.
Exp. 5. But when C is never so little immersed in the water immediately the water in the tube runs out in drops at the orifice A, though the length A B be considerably less than the height C F.
Mr. Hawksbee, in his book of Experiments, has advanced another observation, namely, that the shorter leg of a capillary siphon, as A B F C, must be immersed in the water to the depth F C, which is equal to the height of the column, that would be suspended in it, before the water will run out of the longer leg.
Exp. 6. From what mistake this has proceeded, I cannot imagine; for the water runs out at the longer leg, as soon as the orifice of the shorter leg comes to touch the surface of the stagnant water, without being at all immersed therein.
Jurin's attitude concerning his friend's discovery is pleasing. He appears to have had better judgment than to rush into print, or herald forth that Perpetual Motion had been accomplished. Indeed, the account as given to the Royal Society was that of an experiment and a failure. Nevertheless, it presents an interesting point. Capillary Attraction, however, creates no newenergy. Adhesion is a force, and is often quite a strong force in nature.
If a rod or tube be held by the hand at one end, and the other end inserted in a liquid, it will be observed that in some instances, depending upon the nature of the material of the rod or tube, and the liquid, at the point of contact the liquid will slightly rise in the tube and on the outside edges of the tube. In other instances it will be depressed slightly at the same point. Whether it will be elevated or depressed depends on whether the adhesion of the liquid to the material of which the tube or rod is composed is greater than the cohesion of the particles of the liquid.
If there be a depression it is manifest that the entire surface of the liquid will be slightly elevated by reason of the depression. On the contrary, if the liquid adheres to and creeps slightly upward on the tube or rod, then it is manifest that the surface of the liquid will come to rest slightly lower than though it did not so creep.
The net result finally gets back to the principle of flotation. The immersion or insertion is a little more difficult in the case of depression, and a little easier in the case of elevation. There is no gain or loss of energy. It simply increases in one case, and diminishes in the other case the amount of displacement, with all the resulting mechanical phenomena.
As stated in the preface of this work, pursuit of Perpetual Motion has by no means been confined to mechanics and tradesmen. Many men eminent, and even famous in professions, art and science have devoted much time and thought to the subject. Among such eminent men is to be mentioned Sir William Congreve, of England, a baronet. He was born 1772, and died in 1828. He was an artillerist and an inventor, and was a son of Lieutenant General Sir William Congreve; was distinguished as a military man, as a member of parliament, and as a business man; was an inventor of note, having invented a war rocket, a gun-recoil mounting, a time-fuse, a parachute attachment for rockets, a hydro-pneumatic canal lock sluice, a process for color painting, a new form of steam engine, a method of consuming smoke, a clock which measured time by a ball rolling down an inclined plane, besides other inventions and discoveries. He published a large number of works on scientific subjects.
It is not, therefore, surprising that whatever Sir William Congreve said or did concerning any scientific or mechanical subject should have attracted general attention.
He devised and made a Perpetual Motion Machine, which, like all others, failed to work. We submit that his plan is peculiarly ingenious,and we fail to see how, without a knowledge of the principles of Conservation of Energy, the Congreve idea should not have appealed to any one as reasonable, and its failure puzzling.
An account of the Congreve device and an explanation of his ideas appeared in "The Atlas" in 1827, and the following description is taken from the article appearing in "The Atlas":
The celebrated Boyle entertained an idea that perpetual motion might be obtained by means of capillary attraction; and, indeed, there seems but little doubt that nature has employed this force in many instances to produce this effect.There are many situations in which there is every reason to believe that the sources of springs on the tops and sides of mountains depend on the accumulation of water created at certain elevations by the operation of capillary attraction, acting in large masses of porous material, or through laminated substances. These masses being saturated, in process of time become the sources of springs and the heads of rivers; and thus, by an endless round of ascending and descending waters, form, on the great scale of nature, an incessant cause of perpetual motion, in the purest acceptance of the term, and precisely on the principle that was contemplated by Boyle. It is probable, however, that any imitation of this process on the limited scale practicable by human art would not be of sufficient magnitude to be effective. Nature, by the immensity of her operations, is able to allow for a slowness of process whichwould baffle the attempts of man in any direct and simple imitation of her works. Working, therefore, upon the same causes, he finds himself obliged to take a more complicated mode to produce the same effect.To amuse the hours of a long confinement from illness, Sir William Congreve has recently contrived a scheme of perpetual motion, founded on this principle of capillary attraction, which, it is apprehended, will not be subject to the general refutation applicable to those plans in which the power is supposed to be derived from gravity only. Sir William's perpetual motion is as follows:Let A B C be three horizontal rollers fixed in a frame;a a a, etc., is an endless band of sponge, running round these rollers; andb b b, etc., is an endless chain of weights, surrounding the band of sponge, and attached to it, so that theymust move together; every part of this band and chain being so accurately uniform in weight that the perpendicular side A B will, in all positions of the band and chain, be in equilibrium with the hypothenuse A C, on the principle of the inclined plane. Now, if the frame in which these rollers are fixed be placed in a cistern of water, having its lower part immersed therein, so that the water's edge cuts the upper part of the rollers B C, then, if the weight and quantity of the endless chain be duly proportioned to the thickness and breadth of the band of sponge, the band and chain will, on the water in the cistern being brought to the proper level, begin to move round the rollers in the direction A B, by the force of capillary attraction, and will continue so to move. The process is as follows:On the side A B of the triangle, the weightsb b b, etc., hanging perpendicularly alongside the band of sponge, the band is not compressed by them, and its pores being left open, the water at the pointx, at which the band meets its surface, will rise to a certain height,y, above its level, and thereby create a load, which load will not exist on the ascending side C A, because on this side the chain of weights compresses the band at the water's edge, and squeezes out any water that may have previously accumulated in it; so that the band rises in a dry state, the weight of the chain having been so proportioned to the breadth and thickness of the band as to be sufficient to produce this effect. The load, therefore, on the descending side A B, not being opposed by anysimilar load on the ascending side, and the equilibrium of the other parts not being disturbed by the alternate expansion and compression of the sponge, the band will begin to move in the direction A B; and as it moves downwards, the accumulation of water will continue to rise, and thereby carry on a constant motion, provided the load atx ybe sufficient to overcome the friction on the rollers A B C.Now, to ascertain the quantity of this load in any particular machine, it must be stated that it is found by experiment that the water will rise in a fine sponge about an inch above its level; if, therefore, the band and sponge be one foot thick and six feet broad, the area of its horizontal section in contact with the water would be 864 square inches, and the weight of the accumulation of water raised by the capillary attraction being one inch rise upon 864 square inches, would be 30 lbs., which, it is conceived, would be much more than equivalent to the friction of the rollers.The deniers of this proposition, on the first view of the subject, will say, it is true the accumulation of the weight on the descending side thus occasioned by the capillary attraction would produce a perpetual motion, if there were not as much power lost on the ascending side by the change of position of the weights, in pressing the water out of the sponge.The point now to be established is, that the change in the position of the weights will not cause any loss of power. For this purpose, we must refer to the following diagram.With reference to this diagram, supposea a a, etc., an endless strap, andb b b, etc., an endless chain running round the rollers; A B C not having any sponge between them, but kept at a certain distance from each other by small and inflexible props,p p p, etc., then the sides A B and C A would, in all positions of this system, be precisely an equilibrium, so as to require only a small increment of weight on either side to produce motion. Now, we contend that this equilibrium would still remain unaffected, if small springs were introduced in lieu of the inflexible propsp p p, so that the chainb b bmight approach the lower strapa a a, by compressing these small springs with its weight on the ascending side; for although the centre of gravity of any portion of chain would move in a different line in the latter case—for instance, in the dotted line—still the quantity of the actual weight of every inch of thestrap and chain would remain precisely the same in the former case, where they are kept at the same distance in all positions, as in the latter case, where they approach on the ascending side; and so, also, these equal portions of weights, notwithstanding any change of distance between their several parts which may take place in one case and not in the other, would in both cases rise and fall, though the same perpendicular space, and consequently the equilibrium, would be equally preserved in both cases, though in the first case they may rise and fall through rather more than in the second. The application of this demonstration to the machine described in Fig. 1, is obvious; for the compression of the sponge by the sinking of the weights on the ascending side, in pressing out the water, produces precisely the same effect as to the position and ascent of the weights, as the approach of the chain to the lower strap on the ascending side, in Fig. 2, by the compression of the springs; and consequently, if the equilibrium is not affected in one case—that is, in Fig. 2, as above demonstrated—it will not be affected in the other case, Fig. 1; and, therefore, the water would be squeezed out by the pressure of the chain without any loss of power. The quantity of weight necessary for squeezing dry any given quantity of sponge must be ascertained and duly apportioned by experiment. It is obvious, however, that whether one cubic inch of sponge required one, two, or four ounces for this purpose, it would not affect the equilibrium, since, whatever were the proportion on the ascending side, precisely thesame would the proportion be on the descending side.This principle is capable of application in various ways, and with a variety of materials. It may be produced by a single roller or wheel. Mercury may also be substituted for water, by using a series of metallic plates instead of sponges; and, as the mercury will be found to rise to a much greater height between these plates, than water will do in a sponge, it will be found that the power to be obtained by the latter materials will be from 70 to 80 times as great as by the use of water. Thus, a machine, of the same dimensions as given above, would have a constant power of 2,000 lbs. acting upon it.We now proceed to show how the principle of perpetual motion proposed by Sir William Congreve may be applied upon one centre instead of three.In the following figure,a b c drepresents a drum-wheel or cylinder, moving on a horizontal axis surrounded with a band of sponge 1 2 3 4 5 6 7 8, and immersed in water, so that the surface of the water touches the lower end of the cylinder. Now then, if, as in Fig. 2, the water on the descending sidebbe allowed to accumulate in the sponge atx, while, on the ascending side D, the sponge at the water's edge shall, by any means not deranging the equilibrium, be so compressed that it shall quit the water in a dry state, the accumulation of water above its level atx, by the capillary attraction, will be a source of constant rotary motion; and, in the present case, it willbe found that the means of compressing the sponge may be best obtained by buoyancy, instead of weight.For this purpose, therefore, the band of sponge is supposed to be divided into eight or more equal parts, 1 2 3 4, etc., each part being furnished with a float or buoyant vessel,f1,f2, etc., rising and falling upon spindles,s s s, etc., fixed in the periphery of the drum; these floats being of such dimensions that, when immersed in water, the buoyancy or pressure upwards of each shall be sufficient to compress that portion of the sponge connected with it, so as to squeeze out any water it may have absorbed. These floats are further arranged by means of leversl l l, etc., and platesp p p, etc., so that, when the floatfNo. 1 becomes immersed in the water, its buoyant pressure upwards acts not against the portion of the sponge No. 1, immediately above it, but against No. 2, next in front of it; and so, in like manner, the buoyancy offNo. 2 float acts on the portion of the sponge No. 3, andfNo. 3 float upon No. 4 sponge.Now, from this arrangement it follows, that the portion of sponge No. 4, which is about to quit the water, is pressed upon by that float, which, from acting vertically, is most efficient in squeezing the sponge dry; while that portion of the sponge No. 1, on the point of entering the water, is not compressed at all from its corresponding float No. 8, not having yet reached the edge of the water. By these means, therefore, it will be seen that the sponge always rises in a dry state fromthe water on the ascending side, while it approaches the water on the descending side in an uncompressed state, and open to the full action of absorption by the capillary attraction.The great advantage of effecting this by the buoyancy of light vessels instead of a burthen of weights, as in Fig. 2, is that, by a due arrangement of the dimensions and buoyancy of the floats immersed, the whole machine may be made to float on the surface of the water, so as to take off all friction whatever from the centre of suspension. Thus, therefore, we have a cylindrical machine revolving on a single centre without friction, and having a collection of water in the sponge on the descending side, while the sponge on the ascending side is continually dry; and if this cylinder be six feet wide, and the sponge that surrounds it one foot thick, there will be a constant moving power of thirty pounds on thedescending side, without any friction to counteract it.It has been already stated, that to perpetuate the motion of this machine, the means used to leave the sponge open on the descending side, and press it dry on the ascending side, must be such as will not derange the equilibrium of the machine when floating in water. As, therefore, in this case the effect is produced by the ascent of the buoyant floatsb, to demonstrate the perpetuity of the motion, we must show that the ascent of the floatsfNo. 1 andfNo. 3 will be equal in all corresponding situations on each side of the perpendicular; for the only circumstance that could derange the equilibrium on this system, would be thatfNo. 1 andfNo. 3 should not in all such corresponding situations approach the centre of motion equally; for it is evident that in the position of the floats described in the above figure, iffNo. 1 float did not approach the centre as much asfNo. 3, the equilibrium would be destroyed, and the greater distance offNo. 1 from the centre than that of f No. 3 would create a resistance to the moving force caused by the accumulation of the water atx.It will be found, however, that the floatsfNo. 1 andfNo. 3 do retain equal distances from the centre in all corresponding situations, for the resistance to their approach to the centre by buoyancy is the elasticity of the sponge at the extremity of the respective levers; and as this elasticity is the same in all situations, while this centrifugal force of the floatfNo. 1 is equal tothat of the floatfNo. 3, at equal distances from the perpendicular, the floatsfNo. 1 andfNo. 3 will, in all corresponding situations on either side of the perpendicular, be at equal distances from the centre. It is true, that the force by which these floats approach the centre of motion varies according to the obliquity of the spindles on which they work, it being greatest in the perpendicular position; but, as the obliquity of these spindles is the same at all equal distances from the perpendicular, and as the resistance of the ascent of the floats is equal in all cases, the center of buoyancy will evidently describe a similar curve on each side of the perpendicular; and consequently the equilibrium will be preserved, so as to leave a constant moving force atx, equal to the whole accumulation of water in the sponge. Nor will this equilibrium be disturbed by any change of position in the floats not immersed in the water, since, being duly connected with the sponge by the levers and plates, they will evidently arrange themselves at equal distances from the center, in all corresponding situations on either side.It may be said that the equilibrium of the band of sponge may be destroyed by its partial compression; and it must be admitted that the centre of gravity of the part compressed, according to the construction above described, does approach the center of motion nearer than the center of gravity of the part not compressed. The whole weight of the sponge is, however, so inconsiderable, that this difference would scarcely produce any sensible effect; and if it did, a very slightalteration in the construction, by which the sponge should be compressed as much outwards as inwards, would retain the center of gravity of the compressed part at the same distance from the center of motion as the center of gravity of the part not compressed.
The celebrated Boyle entertained an idea that perpetual motion might be obtained by means of capillary attraction; and, indeed, there seems but little doubt that nature has employed this force in many instances to produce this effect.
There are many situations in which there is every reason to believe that the sources of springs on the tops and sides of mountains depend on the accumulation of water created at certain elevations by the operation of capillary attraction, acting in large masses of porous material, or through laminated substances. These masses being saturated, in process of time become the sources of springs and the heads of rivers; and thus, by an endless round of ascending and descending waters, form, on the great scale of nature, an incessant cause of perpetual motion, in the purest acceptance of the term, and precisely on the principle that was contemplated by Boyle. It is probable, however, that any imitation of this process on the limited scale practicable by human art would not be of sufficient magnitude to be effective. Nature, by the immensity of her operations, is able to allow for a slowness of process whichwould baffle the attempts of man in any direct and simple imitation of her works. Working, therefore, upon the same causes, he finds himself obliged to take a more complicated mode to produce the same effect.
To amuse the hours of a long confinement from illness, Sir William Congreve has recently contrived a scheme of perpetual motion, founded on this principle of capillary attraction, which, it is apprehended, will not be subject to the general refutation applicable to those plans in which the power is supposed to be derived from gravity only. Sir William's perpetual motion is as follows:
Let A B C be three horizontal rollers fixed in a frame;a a a, etc., is an endless band of sponge, running round these rollers; andb b b, etc., is an endless chain of weights, surrounding the band of sponge, and attached to it, so that theymust move together; every part of this band and chain being so accurately uniform in weight that the perpendicular side A B will, in all positions of the band and chain, be in equilibrium with the hypothenuse A C, on the principle of the inclined plane. Now, if the frame in which these rollers are fixed be placed in a cistern of water, having its lower part immersed therein, so that the water's edge cuts the upper part of the rollers B C, then, if the weight and quantity of the endless chain be duly proportioned to the thickness and breadth of the band of sponge, the band and chain will, on the water in the cistern being brought to the proper level, begin to move round the rollers in the direction A B, by the force of capillary attraction, and will continue so to move. The process is as follows:
On the side A B of the triangle, the weightsb b b, etc., hanging perpendicularly alongside the band of sponge, the band is not compressed by them, and its pores being left open, the water at the pointx, at which the band meets its surface, will rise to a certain height,y, above its level, and thereby create a load, which load will not exist on the ascending side C A, because on this side the chain of weights compresses the band at the water's edge, and squeezes out any water that may have previously accumulated in it; so that the band rises in a dry state, the weight of the chain having been so proportioned to the breadth and thickness of the band as to be sufficient to produce this effect. The load, therefore, on the descending side A B, not being opposed by anysimilar load on the ascending side, and the equilibrium of the other parts not being disturbed by the alternate expansion and compression of the sponge, the band will begin to move in the direction A B; and as it moves downwards, the accumulation of water will continue to rise, and thereby carry on a constant motion, provided the load atx ybe sufficient to overcome the friction on the rollers A B C.
Now, to ascertain the quantity of this load in any particular machine, it must be stated that it is found by experiment that the water will rise in a fine sponge about an inch above its level; if, therefore, the band and sponge be one foot thick and six feet broad, the area of its horizontal section in contact with the water would be 864 square inches, and the weight of the accumulation of water raised by the capillary attraction being one inch rise upon 864 square inches, would be 30 lbs., which, it is conceived, would be much more than equivalent to the friction of the rollers.
The deniers of this proposition, on the first view of the subject, will say, it is true the accumulation of the weight on the descending side thus occasioned by the capillary attraction would produce a perpetual motion, if there were not as much power lost on the ascending side by the change of position of the weights, in pressing the water out of the sponge.
The point now to be established is, that the change in the position of the weights will not cause any loss of power. For this purpose, we must refer to the following diagram.
With reference to this diagram, supposea a a, etc., an endless strap, andb b b, etc., an endless chain running round the rollers; A B C not having any sponge between them, but kept at a certain distance from each other by small and inflexible props,p p p, etc., then the sides A B and C A would, in all positions of this system, be precisely an equilibrium, so as to require only a small increment of weight on either side to produce motion. Now, we contend that this equilibrium would still remain unaffected, if small springs were introduced in lieu of the inflexible propsp p p, so that the chainb b bmight approach the lower strapa a a, by compressing these small springs with its weight on the ascending side; for although the centre of gravity of any portion of chain would move in a different line in the latter case—for instance, in the dotted line—still the quantity of the actual weight of every inch of thestrap and chain would remain precisely the same in the former case, where they are kept at the same distance in all positions, as in the latter case, where they approach on the ascending side; and so, also, these equal portions of weights, notwithstanding any change of distance between their several parts which may take place in one case and not in the other, would in both cases rise and fall, though the same perpendicular space, and consequently the equilibrium, would be equally preserved in both cases, though in the first case they may rise and fall through rather more than in the second. The application of this demonstration to the machine described in Fig. 1, is obvious; for the compression of the sponge by the sinking of the weights on the ascending side, in pressing out the water, produces precisely the same effect as to the position and ascent of the weights, as the approach of the chain to the lower strap on the ascending side, in Fig. 2, by the compression of the springs; and consequently, if the equilibrium is not affected in one case—that is, in Fig. 2, as above demonstrated—it will not be affected in the other case, Fig. 1; and, therefore, the water would be squeezed out by the pressure of the chain without any loss of power. The quantity of weight necessary for squeezing dry any given quantity of sponge must be ascertained and duly apportioned by experiment. It is obvious, however, that whether one cubic inch of sponge required one, two, or four ounces for this purpose, it would not affect the equilibrium, since, whatever were the proportion on the ascending side, precisely thesame would the proportion be on the descending side.
This principle is capable of application in various ways, and with a variety of materials. It may be produced by a single roller or wheel. Mercury may also be substituted for water, by using a series of metallic plates instead of sponges; and, as the mercury will be found to rise to a much greater height between these plates, than water will do in a sponge, it will be found that the power to be obtained by the latter materials will be from 70 to 80 times as great as by the use of water. Thus, a machine, of the same dimensions as given above, would have a constant power of 2,000 lbs. acting upon it.
We now proceed to show how the principle of perpetual motion proposed by Sir William Congreve may be applied upon one centre instead of three.
In the following figure,a b c drepresents a drum-wheel or cylinder, moving on a horizontal axis surrounded with a band of sponge 1 2 3 4 5 6 7 8, and immersed in water, so that the surface of the water touches the lower end of the cylinder. Now then, if, as in Fig. 2, the water on the descending sidebbe allowed to accumulate in the sponge atx, while, on the ascending side D, the sponge at the water's edge shall, by any means not deranging the equilibrium, be so compressed that it shall quit the water in a dry state, the accumulation of water above its level atx, by the capillary attraction, will be a source of constant rotary motion; and, in the present case, it willbe found that the means of compressing the sponge may be best obtained by buoyancy, instead of weight.
For this purpose, therefore, the band of sponge is supposed to be divided into eight or more equal parts, 1 2 3 4, etc., each part being furnished with a float or buoyant vessel,f1,f2, etc., rising and falling upon spindles,s s s, etc., fixed in the periphery of the drum; these floats being of such dimensions that, when immersed in water, the buoyancy or pressure upwards of each shall be sufficient to compress that portion of the sponge connected with it, so as to squeeze out any water it may have absorbed. These floats are further arranged by means of leversl l l, etc., and platesp p p, etc., so that, when the floatfNo. 1 becomes immersed in the water, its buoyant pressure upwards acts not against the portion of the sponge No. 1, immediately above it, but against No. 2, next in front of it; and so, in like manner, the buoyancy offNo. 2 float acts on the portion of the sponge No. 3, andfNo. 3 float upon No. 4 sponge.
Now, from this arrangement it follows, that the portion of sponge No. 4, which is about to quit the water, is pressed upon by that float, which, from acting vertically, is most efficient in squeezing the sponge dry; while that portion of the sponge No. 1, on the point of entering the water, is not compressed at all from its corresponding float No. 8, not having yet reached the edge of the water. By these means, therefore, it will be seen that the sponge always rises in a dry state fromthe water on the ascending side, while it approaches the water on the descending side in an uncompressed state, and open to the full action of absorption by the capillary attraction.
The great advantage of effecting this by the buoyancy of light vessels instead of a burthen of weights, as in Fig. 2, is that, by a due arrangement of the dimensions and buoyancy of the floats immersed, the whole machine may be made to float on the surface of the water, so as to take off all friction whatever from the centre of suspension. Thus, therefore, we have a cylindrical machine revolving on a single centre without friction, and having a collection of water in the sponge on the descending side, while the sponge on the ascending side is continually dry; and if this cylinder be six feet wide, and the sponge that surrounds it one foot thick, there will be a constant moving power of thirty pounds on thedescending side, without any friction to counteract it.
It has been already stated, that to perpetuate the motion of this machine, the means used to leave the sponge open on the descending side, and press it dry on the ascending side, must be such as will not derange the equilibrium of the machine when floating in water. As, therefore, in this case the effect is produced by the ascent of the buoyant floatsb, to demonstrate the perpetuity of the motion, we must show that the ascent of the floatsfNo. 1 andfNo. 3 will be equal in all corresponding situations on each side of the perpendicular; for the only circumstance that could derange the equilibrium on this system, would be thatfNo. 1 andfNo. 3 should not in all such corresponding situations approach the centre of motion equally; for it is evident that in the position of the floats described in the above figure, iffNo. 1 float did not approach the centre as much asfNo. 3, the equilibrium would be destroyed, and the greater distance offNo. 1 from the centre than that of f No. 3 would create a resistance to the moving force caused by the accumulation of the water atx.
It will be found, however, that the floatsfNo. 1 andfNo. 3 do retain equal distances from the centre in all corresponding situations, for the resistance to their approach to the centre by buoyancy is the elasticity of the sponge at the extremity of the respective levers; and as this elasticity is the same in all situations, while this centrifugal force of the floatfNo. 1 is equal tothat of the floatfNo. 3, at equal distances from the perpendicular, the floatsfNo. 1 andfNo. 3 will, in all corresponding situations on either side of the perpendicular, be at equal distances from the centre. It is true, that the force by which these floats approach the centre of motion varies according to the obliquity of the spindles on which they work, it being greatest in the perpendicular position; but, as the obliquity of these spindles is the same at all equal distances from the perpendicular, and as the resistance of the ascent of the floats is equal in all cases, the center of buoyancy will evidently describe a similar curve on each side of the perpendicular; and consequently the equilibrium will be preserved, so as to leave a constant moving force atx, equal to the whole accumulation of water in the sponge. Nor will this equilibrium be disturbed by any change of position in the floats not immersed in the water, since, being duly connected with the sponge by the levers and plates, they will evidently arrange themselves at equal distances from the center, in all corresponding situations on either side.
It may be said that the equilibrium of the band of sponge may be destroyed by its partial compression; and it must be admitted that the centre of gravity of the part compressed, according to the construction above described, does approach the center of motion nearer than the center of gravity of the part not compressed. The whole weight of the sponge is, however, so inconsiderable, that this difference would scarcely produce any sensible effect; and if it did, a very slightalteration in the construction, by which the sponge should be compressed as much outwards as inwards, would retain the center of gravity of the compressed part at the same distance from the center of motion as the center of gravity of the part not compressed.
A few years ago air was liquefied. This was accomplished by a very high compression accompanied by a very low temperature.
It is manifest that when liquid air is removed from the extremely low temperature necessary for its liquefaction, and introduced into ordinary atmospheric temperatures, it will exert a most tremendous expansive force which can be utilized for driving machinery and thereby producing heat or electricity, or for any other purpose for which force is required. But, by the law of Conservation of Energy, the liquefied air by expansion can yield no more energy than was required to extract the heat from the air and compress it into the liquid state.
One enthusiastic individual who had worked in a plant for liquefying air announced throughout the United States of America, and perhaps throughout the civilized world, that he had a device by which the expansive force of three pounds of liquid air could be made to liquefy ten pounds, and that seven of the ten could be utilized for driving machinery, or for any other purpose for which force is required, the remaining three being utilized in the production of another tenpounds of liquid air, and so on ad infinitum. He boldly announced that thereby he had discovered an inexhaustible supply of energy at a nominal cost, whereby we could all be warmed and have our machinery of all kinds driven without the expense of gas, coal, fuel of any kind, wind, waves, tides or streams. This enthusiastic individual produced considerable excitement for a time, and then the public ceased to hear about either him or his device. He dropped out of sight and his name sank into oblivion. His claims were absurd, and the absurdity is readily apparent to anyone versed in thermodynamics or familiar with the principles of Conservation of Energy.
There was little excuse for his ever having made such pretentions or for his pretentions ever to have been seriously listened to by any one; for the principle of Conservation of Energy had years before been fully established and heralded throughout the world.
A few years ago when the remarkable properties of radium were discovered it was thought by many that here at last was the long sought solution of the problem of Perpetual Motion. Radium seemed to have the power of maintaining its own temperaturepermanentlyabove that of surrounding bodies. Many versed in the science of thermodynamics (heat power) shook their heads in doubt. If, indeed, it were really true that the substance, radium, or any other substance had the quality of remaining permanently warmer than surrounding bodies without having heat supplied to it, then, indeed, there was an inexhaustible supply of heat, and consequently power.
Hon. R. J. Strutt (Lord Rayleigh), devised a radium clock to run on this principle, consisting of a vacuum vessel in which was suspended a radio-active substance contained in a tube. At the lower end of the tube are two gold leaves as in an electroscope. Platinum wires extended through the glass and touched the gold leaves. The other end of the platinum wires are extended to connect with the earth. The radio-active substanceelectrifies the gold leaves and causes them to be extended, and upon being extended they come in contact with the platinum wires and their charge of electricity is lost, being conducted through the wires and dispersed in the earth, and the leaves losing their charge fall by the force of gravity from the wires back to their position near the tube containing the radio-active substance to be again charged, to again move to and touch the platinum wires, and again lose their charge; this process to go on indefinitely.
Here, indeed, was Perpetual Motion, except for the fact that further and more refined experiments and investigations demonstrated that radio-active substances are not permanently radio-active, but gradually, though very slowly, lose their radio-activity just as a fire will finally burn out, no matter how slowly it burns, or just as an electric battery will finally lose its charge and become exhausted.
This loss, however, of radio-active energy in radio-active substances is so slow that it is said the Strutt clock will run for over one thousand years. But the fact that it will not run permanently, and that the motion is the result of energy supplied by the radio-active substance, and is not supplied by the mechanism itself, deprives it of any right to be called a solution of the problem of self-motive power.
It should be noted that Hon. R. J. Strutt (Lord Rayleigh) of England, who devised the radium clock, above mentioned, is not to be classed with the ordinary Perpetual Motion enthusiast. He was, and is, in fact, a man of very great scientific ability and attainments, and has to his credit many actual and splendid achievements demonstrating him to be a genius of the rarest and most exalted type. His radium clock is founded on correct principles, and surely a clock that will run one thousand years without having power supplied from an outside source is worth while. It should be here also mentioned that the force derived from radio-activity in the manner it is applied in the Strutt clock is very slight, and the instrument necessarily extremely delicate.
The author, within twenty years last past, has had his attention called by two different persons, each ignorant of the efforts of the other, who were seeking to obtain Perpetual Motion by utilizing certain physical facts concerning Momentum and Energy. These facts and the principles out of which they grow are familiar to all who understand thoroughly, even the rudiments of physics; but to persons who are inclined to mechanics, but who have never had the advantages of the presentation of clear principles, they are confusing, and it is surprising that they have not become more fertile fields for Perpetual Motion workers. However, we are unable to find any written or printed account or description of a plan or device of that kind, and our information is confined to instances that have been brought to our personal observation, and concerning which the advice and counsel of the author was sought.
The worker in each case was a man of more than ordinary natural intelligence, and with a bent for mechanical pursuits and reflection. Eachhad taken a course in what is conventionally called High School Physics.
The idea in each case was so novel and interesting that we deem the presentation worth while. They were so nearly alike that instead of attempting to narrate what they said, we will endeavor in our own way to present the idea, and then to give our explanation, showing wherein lay their error.
The following definitions and laws of physics may be regarded as established:
Momentumis the quantity of motion of a moving body, and is the velocity multiplied by the weight.
Thus, a body weighing two pounds, moving at four feet per second, may be represented as having a momentum of eight.
A body weighing two pounds moving at the rate of six feet per second may be said to have a momentum of twelve.
A body weighing ten pounds moving at the rate of ten feet per second will have a momentum of one hundred—and so on.
Now, a step further. A body in motion striking another body free to move will lose part of its motion, and will impart some of its motion to the body moved against. The aggregate momentumafter the striking is the same as before—that is to say—if a body weighing ten pounds have a velocity of twenty feet per second, its momentum we will call two hundred. Now, if in moving it strike another body either larger or smaller its motion will be somewhat retarded, and the body struck will possess some motion.
Multiply the weight of each by its motion after the striking, and it will be found that the sum of the products is two hundred. This may be illustrated by swinging balls like pendulums to cords of equal length from a beam, having the arrangement such that balls of different materials and sizes can be substituted at liberty. If a body be drawn back parallel to the beam, and released so as to swing against another swinging body, both will have motion. This motion will, in some cases be a rebounding motion, as in the case of a small elastic body swinging against and striking a larger elastic body, but in all cases the sum total of the momentum after the impingement is the same as before.
The following statement of the law then, is deducible:
The Momentumof one body in motion may be made to impart momentum to another body, the amount of momentum lost by the former being exactly equal to that thus acquired by the latter.
The Momentumof one body in motion may be made to impart momentum to another body, the amount of momentum lost by the former being exactly equal to that thus acquired by the latter.
Before leaving these remarks on momentum the reader should observe carefully what momentum is and bear in mind it is thequantity of motionpossessed by a moving body, and has to do only withmassandvelocity—and takes no account of distance passed through.
Energy is thecapacity to do work, and the energy of a moving body is the amount ofworkit will do, i. e., thedistanceit will move against a resistance by virtue of its tendency to move, before being brought to a state of rest.
Now note, and note carefully, that the amount ofenergy is proportionalto the mass, and to thesquareof the velocity.
Note this carefully: Any body in motionhas both momentum and energy. Its momentum is proportional to its velocity; its energy to thesquareof its velocity. If the velocity be doubled, the momentum will be doubled, but its energy quadrupled. If the velocity be trebled, its momentum will be trebled, but its energy increased nine-fold.
It is important that the student get clearly what is meant by saying that Energy is thecapacity to do work, and is proportional to the square of the velocity.
The capacity to do work means the capacityto move against resistance, i. e., to overcome resistance. The word "work" being used in a purely mechanical sense and in that sense it is used whether the result accomplished is destructive or beneficial.
A revolving fly wheel will run machinery for some time after the application of force has ceased. This is doing work, and represents energy.
A bullet fired from a gun will accomplish destruction before having its motion arrested. This is work—energy.
If a boy throw a ball into a snow bank, its motion will sink it into the snow, but not far, the resistance of the snow will soon bring the ball to rest. The ball overcomes resistance in passing through the snow until it is brought to rest, and thus it does theworkof forcing itself through the snow, and possesses theenergynecessary to do that work.
The overcoming of the resistance of the air by a moving body is work. A steamboat will move for some time in water after the steam has been turned off. The overcoming of the resistance of the water is work, and by virtue of the motion of the boat when the steam was turned off it possessed the energy to do the work of forcing itself for some time through the resistance of the water.
The Perpetual Motion worker in each case had reasoned himself into this conclusion: That the same energy will impart the sameaccelerationof velocity, regardless of the velocity at the beginning of the application of energy. That the same amount of energy or work necessary to impart to a body a velocity of ten feet per second will increase that velocity to twenty feet per second, or from twenty feet per second to thirty feet per second. In other words, that the same amount of energy, and only the same amount of energy is required for a givenincreasein velocity without regard to the initial velocity. This appears plausible, and almost self-evident. We believe the great majority of people, other than mechanical engineers would, upon presentation of the theory accept it as axiomatic, and as a matter of course. The fallacy becomes manifest only from a critical and technical examination of the Laws of Momentum and Energy.
The Perpetual Motion worker had learned from his text-books that if the velocity bedoubled, the energy would bemultiplied by four. His idea was to so arrange his mechanism that he would apply the amount of energy to move a fly wheel free to revolve, from a position of rest to a revolving velocity of ten revolutions per second. Then apply again thesame amount of energy, and accelerate that velocity from ten revolutions persecond to twenty revolutions per second. Thus, the energy at the end of the second second would be four times what it was at the end of the first second. But to make it so, only double the amount of energy had been applied that had been expended at the end of the first second. Thus, he reasoned, his machine was by virtue of its structure, accumulating energy, and this energy could be used one-half to continue the motion of his machine, and the other half to run other machinery, or for any other purpose for which energy might be desired.
Wherein lies the fallacy of this supposition?
We will now endeavor to explain. And for the young student to get the explanation fully, it will be necessary for him to pay the closest attention to what we here state.
A force, for instance the pressure of the finger or the hand, equal to one pound against a body free to move, will, we will say, move that body in one second of time through a space of ten feet, and at the end of that second the body will have a velocity of twenty feet. It is manifest that at the end of the second the velocity will be twenty feet per second for its initial velocity is zero, and its average velocity ten feet per second, the acceleration being, of course, presumed uniform.
Now, it isnottrue as the Perpetual Motionworker had assumed that the same energy—i. e., the same work that is required to increase the velocity from zero to ten feet per second will increase the velocity from ten feet per second to twenty feet per second, andin that assumptionlay the fallacy of our friends who were thus seeking Perpetual Motion.
The greater the velocity, the more energy is required to impart a given acceleration. To increase the velocity from ten feet per second to twenty feet per second, the applied force must continue through one second of time, and more energy is required to follow a rapidly moving body, and continue to apply to it a given force for one second than would be required to follow and maintain the application of the same force to a body moving more slowly—thedistancetraveled is greater in one case than in the other.
It must be plain that if the moving body have a velocity at the end of the first second of twenty feet per second, it will, at the end of the second second, with the same pressure (force) continued against the same resistance, have a velocity of forty feet per second, and at the end of three seconds have a velocity of sixty feet, and at the end of four seconds a velocity of eighty feet, and so on.
Now, at the beginning of the second second it had a velocity of twenty feet, and at the end ofthat second a velocity of forty feet. It therefore, traveled through that second with an average velocity of thirty feet and, of course, during the second second traveled exactly thirty feet. It traveled ten feet the first second, and if it traveled thirty feet the second, then in the two seconds it traveled forty feet—four times as far as it traveled the first second. At the beginning of the third second it had a velocity of forty feet, and at the end of the third second a velocity of sixty feet. The average velocity then for the third second would be one-half the sum of forty feet and plus sixty feet—that is to say, it would be fifty feet, and that would be the distance traveled during the third second. The first second it traveled ten feet, the second second thirty feet, and the third second fifty feet, making a total in three seconds of ninety feet—that is to say, in three seconds it traveled nine times as far as in one second.
It will be noticed from the above that the velocity is proportional to the number of seconds, but that the distance traveled is proportional to thesquareof the number of seconds, and also proportional to the square of the velocity.
Momentum is mass multiplied by velocity; energy is measured by the distance through which a body will move against a given resistance.
Should you prop up one wheel of a carriage and revolve the wheel, then with the pressure ofthe finger or the thumb on the hub as a brake, stop it, it will be found that (omitting the effect of atmospheric resistance), the wheel will make four times as many revolutions before stopping with a doubled velocity; nine times as many with a trebled velocity.
Falling bodies afford the most perfect illustration of the principle of Momentum and Energy, and are so commonly used to illustrate those principles that many students get the idea that the application of those principles is confined to falling bodies, and do not realize that they extend generally through the field of mechanics.
A falling body is, of course, acted upon by gravity with uniform force equal to the weight of the falling body, and that force continues to follow the falling body and to be applied uniformly and equally, however slowly, or rapidly the body may be falling. And, omitting atmospheric resistance, the body is absolutely free to move except for its natural tendency to remain at rest, or at uniform velocity. It is well known that a body falls (almost exactly) sixteen feet in one second, and at the end of one second has a velocity of thirty-two. During the second second it falls through a distance of forty-eight feet, and during the third second a distance of eighty feet. In two seconds it falls sixty-four feet, and in three seconds one hundred twenty-eight feet, and so on.Thus, it will be observed that thevelocityis proportional to the time during which it has fallen, but that the distance fallen in any number of seconds is proportional to thesquareof the time.
This, indeed, is a property of numbers, and results from mathematical law. If the reader will form a series of numbers, setting down any number for the first term of the series, adding to it its double for the second term, and adding to the second term double the first term for the third, and adding double the first term to the third term for the fourth, and so on—in other words, form any increasing arithmetical series with double the first term for the common difference, he will discover that thesum of all the terms is equal to the first term multiplied by the square of the number of terms. Thus: