furnished, at equal distances, with levers, each bearing at its
extremity a weight, and movable on a hinge so that in one direction
they can rest upon the circumference, while on the opposite side,
being carried away by the weight at the extremity, they are obliged
to arrange themselves in the direction of the radius continued. This
being supposed, it is evident that when the wheel turns in the
direction ABC, the weights A, B, and C will recede from the center;
consequently, as they act with more force, they will carry the wheel
towards that side; and as a new lever will be thrown out, in
proportion as the wheel revolves, it thence follows, say they, that
the wheel will continue to move in the same direction. But
notwithstanding the specious appearance of this reasoning,
experience has proved that the machine will not go; and it may
indeed be demonstrated that there is a certain position in which the
center of gravity of all these weights is in the vertical plane
passing through the point of suspension, and that therefore it must
stop."
[Illustration: Fig. 5.]
[Illustration: Fig. 6.]
Another invention of a similar kind is thus described by the same
author:
"In a cylindric drum, in perfect equilibrium on its axis, are formed
channels as seen in Fig. 6, which contain balls of lead or a certain
quantity of quicksilver. In consequence of this disposition, the
balls or quicksilver must, on the one side, ascend by approaching
the center, and on the other must roll towards the circumference.
The machine ought, therefore, to turn incessantly towards that
side."
In his "Course of Lectures on Natural Philosophy," Dr. Thomas Young
speaks of these contrivances as follows:
"One of the most common fallacies, by which the superficial
projectors of machines for obtaining perpetual motion have been
deluded, has arisen from imagining that any number of weights
ascending by a certain path, on one side of the center of motion and
descending on the other at a greater distance, must cause a constant
preponderance on the side of the descent: for this purpose the
weights have either been fixed on hinges, which allow them to fall
over at a certain point, so as to become more distant from the
center, or made to slide or roll along grooves or planes which lead
them to a more remote part of the wheel, from whence they return as
they ascend; but it will appear on the inspection of such a machine,
that although some of the weights are more distant from the center
than others, yet there is always a proportionately smaller number
of them on that side on which they have the greatest power, so that
these circumstances precisely counterbalance each other."
[Illustration: Fig. 7.]
He then gives the illustration (Fig. 7), shown on the preceding page, of
"a wheel supposed to be capable of producing a perpetual motion; the
descending balls acting at a greater distance from the center, but being
fewer in number than the ascending. In the model, the balls may be kept
in their places by a plate of glass covering the wheel."
[Illustration: Fig. 8.]
A more elaborate arrangement embodying the same idea is figured and
described by Ozanam. The machine, which is shown in Fig. 8, consists of
"a kind of wheel formed of six or eight arms, proceeding from a center
where the axis of motion is placed. Each of these arms is furnished with
a receptacle in the form of a pair of bellows: but those on the opposite
arms stand in contrary directions, as seen in the figure. The movable
top of each receptacle has affixed to it a weight, which shuts it in one
situation and opens it in the other. In the last place, the bellows of
the opposite arms have a communication by means of a canal, and one of
them is filled with quicksilver.
"These things being supposed, it is visible that the bellows on the one
side must open, and those on the other must shut; consequently, the
mercury will pass from the latter into the former, while the contrary
will be the case on the opposite side."
Ozanam naively adds: "It might be difficult to point out the deficiency
of this reasoning; but those acquainted with the true principles of
mechanics will not hesitate to bet a hundred to one, that the machine,
when constructed, will not answer the intended purpose."
That this bet would have been a perfectly safe one must be quite evident
to any person who has the slightest knowledge of practical mechanics,
and yet the fundamental idea which is embodied in this and the other
examples which we have just given, forms the basis of almost all the
attempts which have been made to produce a perpetual motion by purely
mechanical means.
The hydrostatic paradox by which a few ounces of liquid may apparently
balance many pounds, or even tons, has frequently suggested a form of
apparatus designed to secure a perpetual motion. Dr. Arnott, in his
"Elements of Physics," relates the following anecdote: "A projector
thought that the vessel of his contrivance, represented here (Fig. 9),
was to solve the renowned problem of the perpetual motion. It was
goblet-shaped, lessening gradually towards the bottom until it became a
tube, bent upwards at _c_ and pointing with an open extremity into the
goblet again. He reasoned thus: A pint of water in the goblet _a_ must
more than counterbalance an ounce which the tube _b_ will contain, and
must, therefore, be constantly pushing the ounce forward into the vessel
again at _a_, and keeping up a stream or circulation, which will cease
only when the water dries up. He was confounded when a trial showed him
the same level in _a_ and in _b_."
[Illustration: Fig. 9.]
This suggestion has been adopted over and over again by sanguine
inventors. Dircks, in his "Perpetuum Mobile," tells us that a
contrivance, on precisely the same principle, was proposed by the Abbe
de la Roque, in "Le Journal des Scavans," Paris, 1686. The instrument
was a U tube, one leg longer than the other and bent over, so that any
liquid might drop into the top end of the short leg, which he proposed
to be made of wax, and the long one of iron. Presuming the liquid to be
more condensed in the metal than the wax tube, it would flow from the
end into the wax tube and so continue.
This is a typical case. A man of learning and of high position is
so confident that his theory is right that he does not think it
worth while to test it experimentally, but rushes into print and
immortalizes himself as the author of a blunder. It is safe to say
that this absurd invention will do more to perpetuate his name than
all his learning and real achievements. And there are others in the
same predicament--circle-squarers who, a quarter of a century hence,
will be remembered for their errors when all else connected with them
will be forgotten.
To every miller whose mill ceased working for want of water, the idea
has no doubt occurred that if he could only pump the water back again
and use it a second or a third time he might be independent of dry or
wet seasons. Of course no practical miller was ever so far deluded as to
attempt to put such a suggestion into practice, but innumerable machines
of this kind, and of the most crude arrangement, have been sketched and
described in magazines and papers. Figures of wheels driving an ordinary
pump, which returns to an elevated reservoir the water which has driven
the wheel, are so common that it is not worth while to reproduce any of
them. In the following attempt, however, which is copied from Bishop
Wilkins' famous book, "Mathematical Magic" (1648), the well-known
Archimedean screw is employed instead of a pump, and the naivete of the
good bishop's description and conclusion are well worth the space they
will occupy.
After an elaborate description of the screw, he says: "These things,
considered together, it will hence appear how a perpetual motion may
seem easily contrivable. For, if there were but such a water-wheel made
on this instrument, upon which the stream that is carried up may fall
in its descent, it would turn the screw round, and by that means convey
as much water up as is required to move it; so that the motion must
needs be continual since the same weight which in its fall does turn the
wheel, is, by the turning of the wheel, carried up again. Or, if the
water, falling upon one wheel, would not be forcible enough for this
effect, why then there might be two, or three, or more, according as the
length and elevation of the instrument will admit; by which means the
weight of it may be so multiplied in the fall that it shall be
equivalent to twice or thrice that quantity of water which ascends; as
may be more plainly discerned by the following diagram (Fig. 10):
"Where the figure LM at the bottom does represent a wooden cylinder with
helical cavities cut in it, which at AB is supposed to be covered over
with tin plates, and three waterwheels, upon it, HIK; the lower cistern,
which contains the water, being CD. Now, this cylinder being turned
round, all the water which from the cistern ascends through it, will
fall into the vessel at E, and from that vessel being conveyed upon the
water-wheel H, shall consequently give a circular motion to the whole
screw. Or, if this alone should be too weak for the turning of it, then
the same water which falls from the wheel H, being received into the
other vessel F, may from thence again descend on the wheel I, by which
means the force of it will be doubled. And if this be yet insufficient,
then may the water, which falls on the second wheel I, be received into
the other vessel G, and from thence again descend on the third wheel at
K; and so for as many other wheels as the instrument is capable of. So
that besides the greater distance of these three streams from the center
or axis by which they are made so much heavier; and besides that the
fall of this outward water is forcible and violent, whereas the ascent
of that within is natural--besides all this, there is twice as much
water to turn the screw as is carried up by it.
[Illustration: Fig. 10.]
"But, on the other side, if all the water falling upon one wheel would
be able to turn it round, then half of it would serve with two wheels,
and the rest may be so disposed of in the fall as to serve unto some
other useful, delightful ends.
"When I first thought of this invention, I could scarce forbear, with
Archimedes, to cry out 'Eureka! Eureka!' it seeming so infallible a way
for the effecting of a perpetual motion that nothing could be so much as
probably objected against it; but, upon trial and experience, I find it
altogether insufficient for any such purpose, and that for these two
reasons:
"1. The water that ascends will not make any considerable stream in the
fall.
"2. This stream, though multiplied, will not be of force enough to turn
about the screw."
How well it would have been for many of those inventors, who supposed
that they had discovered a successful perpetual motion, if they had only
given their contrivances a fair and unprejudiced test as did the good
old bishop!
A modification of this device, in which mercury is used instead of
water, is thus described by a correspondent of "The Mechanic's
Magazine." (London.)
"In Fig. 11, A is the screw turning on its two pivots GG; B is a
cistern to be filled above the level of the lower aperture of the
screw with mercury, which I conceive to be preferable to water on
many accounts, and principally because it does not adhere or
evaporate like water; C is a reservoir, which, when the screw is
turned round, receives the mercury which falls from the top; there
is a pipe, which, by the force of gravity, conveys the mercury from
the reservoir C on to (what for want of a better term may be called)
the float-board E, fixed at right angles to the center [axis] of the
screw, and furnished at its circumference with ridges or floats to
intercept the mercury, the moment and weight of which will cause the
float-board and screw to revolve, until, by the proper inclination
of the floats, the mercury falls into the receiver F, from whence it
again falls by its spout into the cistern G, where the constant
revolution of the screw takes it up again as before."
He then suggests some difficulties which the ball, seen just under the
letter E, is intended to overcome, but he confesses that he has never
tried it, and to any practical mechanic it is very obvious that the
machine will not work. But we give the description in the language of
the inventor, as a fair type of this class of perpetual-motion machines.
[Illustration: Fig. 11.]
In the year 1790 a Doctor Schweirs took out a patent for a machine in
which small metal balls were used instead of a liquid, and they were
raised by a sort of chain pump which delivered them upon the
circumference of a large wheel, which was thus caused to revolve. It was
claimed for this invention that it kept going for some months, but any
mechanic who will examine the Doctor's drawing must see that it could
not have continued in motion after the initial impulse had been
expended.
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 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 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:
[Illustration: 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
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 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 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 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 accumulation 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 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 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 damning 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
brass model of a time-piece, in which were two steel balls 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 pass 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 glass, for the purpose
of seeing the action of the balls 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 balls, which
will sink one-fourth of their bulk in water (of course will fall in
air); the weight therefore of three balls resting upon one ball in
water, as at E, will just bring its top even with the water's edge; the
weight of four balls 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 balls) 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 passed 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, pass 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 pass 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 balls 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."
[Illustration: 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: