That property of liquids known as capillary attraction has been frequently called to the aid of perpetual-motion seekers, and the fact that although water will, in capillary tubes and sponges, rise several inches above the general level, it will not overflow, has been a startling surprise to the would-be inventors. Perhaps the most notable instance of a mistake of this kind occurred in the case of the famous Sir William Congreve, the inventor of the military rockets that bore his name, and the author of certain improvements in matches which were called after him. It was thus described and figured in an article which appeared in the "Atlas" (London) and was copied into "The Mechanic's Magazine" (London) for 1827:

"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 acc.u.mulation of water created at certain elevations by the operation of capillary attraction, acting in large ma.s.ses of porous material, or through laminated substances. These ma.s.ses 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 which would 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:

[Ill.u.s.tration: Fig. 12.]

"Let ABC, Fig. 12, be three horizontal rollers fixed in a frame; aaa, etc., is an endless band of sponge, running round these rollers; and bbb, etc., is an endless chain of weights, surrounding the band of sponge, and attached to it, so that they must move together; every part of this band and chain being so accurately uniform in weight that the perpendicular side AB will, in all positions of the band and chain, be in equilibrium with the hypothenuse AC, 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 BC, then, if the weight and quant.i.ty 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 AB, by the force of capillary attraction, and will continue so to move. The process is as follows:

"On the side AB of the triangle, the weights bbb, 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 point x, 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 CA, 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 acc.u.mulated 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 AB, not being opposed by any similar 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 AB; and as it moves downwards, the acc.u.mulation of water will continue to rise, and thereby carry on a constant motion, provided the load at xy be sufficient to overcome the friction on the rollers ABC.

"Now to ascertain the quant.i.ty 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 acc.u.mulation of water raised by the capillary attraction being one inch rise upon 864 square inches, would be 30 lb., which, it is conceived, would be much more than equivalent to the friction of the rollers."

The article, inspired no doubt by Sir William, then goes on to give elaborate reasons for the success of the device, but all these are met by the d.a.m.ning fact that the machine never worked. Some time afterwards Sir William, at considerable expense, published a pamphlet in which he explained and defended his views. If he had only had a working model made and the thing had continued in motion for a few hours, he would have silenced all objectors far more quickly and forcibly than he ever could have done by any amount of argument.

And in his case there could have been no excuse for his not making a small machine after the plans that he published and even patented. He was wealthy and could have commanded the services of the best mechanics in London, but no working model was ever made. Many inventors of perpetual-motion machines offer their poverty as an excuse for not making a model or working machine. Thus Dircks, in his "Perpetuum Mobile" gives an account of "a mechanic, a model maker, who had a neat bra.s.s model of a time-piece, in which were two steel b.a.l.l.s A and B;--B to fall into a semicircular gallery C, and be carried to the end D of a straight trough DE; while A in its turn rolls to E, and so on continuously; only the gallery C not being screwed in its place, we are desired to take the will for the deed, until twenty shillings be raised to complete this part of the work!"

And Mr. Dircks also quotes from the "Builder" of June, 1847: "This vain delusion, if not still in force, is at least as standing a fallacy as ever. Joseph Hutt, a frame-work knitter, in the neighborhood of the enlightened town of Hinckley, professes to have discovered it [perpetual motion] and only wants twenty pounds, as usual, to set it agoing."

The following rather curious arrangement was described in "The Mechanic's Magazine" for 1825.

"I beg leave to offer the prefixed device. The point at which, like all the rest, it fails, I confess I did not (as I do now) plainly perceive at once, although it is certainly very obvious. The original idea was this--to enable a body which would float in a heavy medium and sink in a lighter one, to pa.s.s successively through the one to the other, the continuation of which would be the end in view. To say that valves cannot be made to act as proposed will not be to show the _rationale_ (if I may so say) upon which the idea is fallacious."

The figure is supposed to be tubular, and made of gla.s.s, for the purpose of seeing the action of the b.a.l.l.s inside, which float or fall as they travel from air through water and from water through air. The foot is supposed to be placed in water, but it would answer the same purpose if the bottom were closed.

DESCRIPTION OF THE ENGRAVING, FIG. 13. No. 1, the left leg, filled with water from B to A. 2 and 3, valves, having in their centers very small projecting valves; they all open upwards. 4, the right leg, containing air from A to F. 5 and 6, valves, having very small ones in their centers; they all open downwards. The whole apparatus is supposed to be air and water-tight. The round figures represent hollow b.a.l.l.s, which will sink one-fourth of their bulk in water (of course will fall in air); the weight therefore of three b.a.l.l.s resting upon one ball in water, as at E, will just bring its top even with the water's edge; the weight of four b.a.l.l.s will sink it under the surface until the ball immediately over it is one-fourth its bulk in water, when the under ball will escape round the corner at C, and begin to ascend.

"The machine is supposed (in the figure) to be in action, and No. 8 (one of the b.a.l.l.s) to have just escaped round the corner at C, and to be, by its buoyancy, rising up to valve No. 3, striking first the small projecting valve in the center, which when opened, the large one will be raised by the buoyancy of the ball; because the moment the small valve in the center is opened (although only the size of a pin's head), No. 2 valve will have taken upon itself to sustain the whole column of water from A to B. The said ball (No. 8) having pa.s.sed through the valve No. 3, will, by appropriate weights or springs, close; the ball will proceed upwards to the next valve (No. 2), and perform the same operation there. Having arrived at A, it will float upon the surface three-fourths of its bulk out of water. Upon another ball in due course arriving under it, it will be lifted quite out of the water, and fall over the point D, pa.s.s into the right leg (containing air), and fall to valve No. 5, strike and open the small valve in its center, then open the large one, and pa.s.s through; this valve will then, by appropriate weights or springs, close; the ball will roll on through the bent tube (which is made in that form to gain time as well as to exhibit motion) to the next valve (No. 6), where it will perform the same operation, and then, falling upon the four b.a.l.l.s at E, force the bottom one round the corner at C. This ball will proceed as did No. 8, and the rest in the same manner successively."

[Ill.u.s.tration: Fig. 13.]

That an ordinary amateur mechanic should be misled by such arguments is perhaps not so surprising, when we remember that the famous John Bernoulli claimed to have invented a perpetual motion based on the difference between the specific gravities of two liquids. A translation of the original Latin may be found in the Encyclopaedia Britannica, Vol.

XVIII, page 555. Some of the premises on which he depends are, however, impossibilities, and Professor Chrystal concludes his notice of the invention thus: "One really is at a loss with Bernoulli's wonderful theory, whether to admire most the conscientious statement of the hypothesis, the prim logic of the demonstration--so carefully cut according to the pattern of the ancients--or the weighty superstructure built on so frail a foundation. Most of our perpetual motions were clearly the result of too little learning; surely this one was the product of too much."

A more simple device was suggested recently by a correspondent of "Power." He describes it thus:

The J-shaped tube A, Fig. 14, is open at both ends, but tapers at the lower end, as shown. A well-greased cotton rope C pa.s.ses over the wheel B and through the small opening of the tube with practically little or no friction, and also without leakage. The tube is then filled with water. The rope above the line WX balances over the pulley, and so does that below the line YZ. The rope in the tube between these lines is lifted by the water, while the rope on the other side of the pulley between these lines is pulled downward by gravity.

[Ill.u.s.tration: Fig. 14.]

The inventor offers the above suggestion rather as a kind of puzzle than as a sober attempt to solve the famous problem, and he concludes by asking why it will not work?

In addition to the usual resistance or friction offered by the air to all motion, there are four drawbacks:

1. The friction in its bearings of the axle of the wheel B.

2. The power required to bend and unbend the rope.

3. The friction of the rope in pa.s.sing through the water from z to x and its tendency to raise a portion of the water above the level of the water at x.

4. The friction at the point y, this last being the most serious of all.

An "opening of the tube with practically little or no friction, and also without leakage" is a mechanical impossibility. In order to have the joint water-tight, the tube must hug the rope very tightly and this would make friction enough to prevent any motion. And the longer the column of water xz, the greater will be the tendency to leak, and consequently the tighter must be the joint and the greater the friction thereby created.

A favorite idea with perpetual-motion seekers is the utilization of the force of magnetism. Some time prior to the year 1579, Joannes Taisnierus wrote a book which is now in the British Museum and in which considerable s.p.a.ce is devoted to "Continual Motions" and to the solving of this problem by magnetism. Bishop Wilkins in his "Mathematical Magick" describes one of the many devices which have been invented with this end in view. He says: "But amongst all these kinds of invention, that is most likely, wherein a loadstone is so disposed that it shall draw unto it on a reclined plane a bullet of steel, which steel as it ascends near to the loadstone, may be contrived to fall down through some hole in the plane, and so to return unto the place from whence at first it began to move; and, being there, the loadstone will again attract it upwards till coming to this hole, it will fall down again; and so the motion shall be perpetual, as may be more easily conceivable by this figure (Fig. 15):

"Suppose the loadstone to be represented at AB, which, though it have not strength enough to attract the bullet C directly from the ground, yet may do it by the help of the plane EF. Now, when the bullet is come to the top of this plane, its own gravity (which is supposed to exceed the strength of the loadstone) will make it fall into that hole at E; and the force it receives in this fall will carry it with such a violence unto the other end of this arch, that it will open the pa.s.sage which is there made for it, and by its return will again shut it: so that the bullet (as at the first) is in the same place whence it was attracted, and, consequently must move perpetually."

[Ill.u.s.tration: Fig. 15.]

Notwithstanding the positiveness of the "must" at the close of his description, it is very obvious to any practical mechanic that the machine will not move at all, far less move perpetually, and the bishop himself, after carefully and conscientiously discussing the objections, comes to the same conclusion. He ends by saying: "So that none of all these magnetical experiments, which have been as yet discovered, are sufficient for the effecting of a perpetual motion, though these kind of qualities seem most conducible unto it, and perhaps hereafter it may be contrived from them."

It has occurred to several would-be inventors of perpetual motion that if some substance could be found which would prevent the pa.s.sage of the magnetic force, then by interposing a plate of this material at the proper moment, between the magnet and the piece of iron to be attracted, a perpetual motion might be obtained. Several inventors have claimed that they had discovered such a non-conducting substance, but it is needless to say that their claims had no foundation in fact, and if they had discovered anything of the kind, it would have required just as much force to interpose it as would have been gained by the interposition. It has been fully proved that in every case where a machine was made to work apparently by the interposition of such a material, a fraud was perpetrated and the machine was really made to move by means of some concealed springs or weights.

A correspondent of the "Mechanic's Magazine" (Vol. xii, London, 1829), gives the following curious design for a "Self-moving Railway Carriage."

He describes it as a machine which, were it possible to make its parts hold together unimpaired by rotation or the ravages of time, and to give it a path encircling the earth, would a.s.suredly continue to roll along in one undeviating course until time shall be no more.

A series of inclined planes are to be erected in such a manner that a cone will ascend one (its sides forming an acute angle), and being raised to the summit, descend on the next (having parallel sides), at the foot of which it must rise on a third and fall on a fourth, and so continue to do alternately throughout.

The diagram, Fig. 16, is the section of a carriage A, with broad conical wheels _a_, _a_, resting on the inclined plane _b_. The entrance to the carriage is from above, and there are ample accommodations for goods and pa.s.sengers. "The most singular property of this contrivance is, that its speed increases the more it is laden; and when checked on any part of the road, it will, when the cause of stoppage is removed, proceed on its journey by mere power of gravity. Its path may be a circular road formed of the inclined planes. But to avoid a circuitous route, a double road ought to be made. The carriage not having a retrograde motion on the inclined planes, a road to set out upon, and another to return by, are indispensable."

[Ill.u.s.tration: Fig. 16.]

How any one could ever imagine that such a contrivance would ever continue in motion for even a short time, except, perhaps, on the famous _descensus averni_, must be a puzzle to every sane mechanic. I therefore give it as a climax to the absurdities which have been proposed in sober earnest. As a fitting close, however, to this chapter of human folly, I give the following joke from the "Penny Magazine," published by the Society for the Diffusion of Useful Knowledge.

"'Father, I have invented a perpetual motion!' said a little fellow of eight years old. 'It is thus: I would make a great wheel, and fix it up like a water-wheel; at the top I would hang a great weight, and at the bottom I would hang a number of little weights; then the great weight would turn the wheel half round and sink to the bottom, because it is so heavy: and when the little weights reach the top they would sink down, because they are so many; and thus the wheel would turn round for ever.'"

The child's fallacy is a type of all the blunders which are made on this subject. Follow a projector in his description, and if it be not perfectly unintelligible, which it often is, it always proves that he expects to find certain of his movements alternately strong and weak--not according to the laws of nature--but according to the wants of his mechanism.

2. FALLACIES

Fallacies are distinguished from absurdities on the one hand and from frauds on the other, by the fact that without any intentionally fraudulent contrivances on the part of the inventor, they seem to produce results which have a tendency to afford to certain enthusiasts a basis of hope in the direction of perpetual motion, although usually not under that name, for that is always explicitly disclaimed by the promoters.

The most notable instance of this cla.s.s in recent times was the application of liquid air as a source of power, the claim having been actually made by some of the advocates of this fallacy that a steamship starting from New York with 1000 gallons of liquid air, could not only cross the Atlantic at full speed but could reach the other side with more than 1000 gallons of liquid air on board--the power required to drive the vessel and to liquefy the surplus air being all obtained during the pa.s.sage by utilizing the original quant.i.ty of liquid air that had been furnished in the first place.

That this was equivalent to perpetual motion, pure and simple, was obvious even to those who were least familiar with such subjects, though the idea of calling it perpetual motion was sternly repudiated by all concerned--the term "perpetual motion" having become thoroughly offensive to the ears of common-sense people, and consequently tending to cast doubt over any enterprise to which it might be applied.

That liquid air is a real and wonderful discovery, and that for a certain small range of purposes it will prove highly useful, cannot be doubted by those who have seen and handled it and are familiar with its properties, but that it will ever be successfully used as an economical source of mechanical power is, to say the least, very improbable. That a small quant.i.ty of the liquid is capable of doing an enormous amount of work, and that under some conditions there is _apparently_ more power developed than was originally required to liquefy the air, is undoubtedly true, but when a careful quant.i.tative examination is made of the outgo and the income of energy, it will be found in this, as in every similar case, that instead of a gain there is a very decided and serious loss. The correct explanation of the fallacy was published in the "Scientific American," by the late Dr. Henry Morton, president of the Stevens Inst.i.tute, and the same explanation and exposure were made by the writer, nearly fifty years ago, in the case of a very similar enterprise. The form of the fallacy in both cases is so similar and so interesting that I shall make no apology for giving the details.

About the year 1853 or 1854, two ingenious mechanics of Rochester, N.

Y., conceived the idea that by using some liquid more volatile than water, a great saving might be effected in the cost of running an engine. At that time gasolene and benzine were unknown in commerce, and the same was true in regard to bisulphide of carbon, but as the process of manufacturing the latter was simple and the sources of supply were cheap and apparently unlimited, they adopted that liquid. The name of one of these inventors was Hughes and that of the other was Hill, and it would seem that each had made the invention independently of the other.

They had a fierce conflict over the patent, but this does not concern us except to this extent, that the records of the case may therefore be found in the archives of the Patent Office at Washington, D.C. Hughes was backed by the wealth of a well-known lawyer of Rochester, whose son subsequently occupied a high office in the state of New York, and he constructed a beautiful little steam-engine and boiler, made of the very finest materials and with such skill and accuracy that it gave out a very considerable amount of power in proportion to its size. The source of heat was a series of lamps, fed, I think, with lard oil (this was before the days of kerosene), and the exhibition test consisted in first filling the boiler with water, and noting the time that it took to get up a certain steam pressure as shown by the gage. After this test, bisulphide of carbon was added to the water, and the time and pressure were noted. The difference was of course remarkable, and altogether in favor of the new liquid. The exhaust was carried into a vessel of cold water and as bisulphide of carbon is very easily condensed and very heavy, almost the entire quant.i.ty used was recovered and used over and over again.

But to the uninstructed onlooker, the most remarkable part of the exhibition was when the steam pressure was so far lowered that the engine revolved very slowly, and then, on a little bisulphide being injected into the boiler, the pressure would at once rise, and the engine would work with great rapidity. This seemed almost like magic.

The same experiment was tried on an engine of twelve horse-power, and with a like result. When the steam pressure had fallen so far that the engine began to move quite slowly, a quant.i.ty of the bisulphide would be injected into the boiler and the pressure would at once rise, the engine would move with renewed vigor, and the fly-wheel would revolve with startling velocity. All this was seen over and over again by myself and others. At that time the writer, then quite a young man, had just recovered from a very severe illness and was making a living by teaching mechanical drawing and making drawings for inventors and others, and in the course of business he was brought into contact with some parties who thought of investing in the new and apparently wonderful invention. They employed him to examine it and give an opinion as to its value. After careful consideration and as thorough a calculation as the data then at command would allow, he showed his clients that the tests which had been exhibited to them proved nothing, and that if a clear proof of the value of the invention was to be given, it must be after a run of many hours and not of a few minutes, and against a properly adjusted load, the amount of which had been carefully ascertained. This test was never made, or if made the results were not communicated to the prospective purchasers; the negotiations fell through, and the invention which was to have revolutionized our mechanical industries fell into "innocuous desuetude."