concealed, it is impossible to say in what this machine consisted;
but as a boiler was used, it is probable, though not certain, that
steam was the agent. There have been various machines proposed, of
which a furnace and boiler form a part, and in which the agency of
steam is not used. The machine of Amontons furnishes an example of
this. It is most probable that the contrivance of Garay was
identical with that of Hero. The low state of the arts in Spain in
the sixteenth century would be incompatible with the construction
of any machine requiring great precision of execution. But the
simplicity of Hero's contrivance would have rendered its
construction and operation quite practicable. As to the claims to
the invention of the steam engine advanced by the advocates of De
Garay, founded on the above document, a refutation is supplied by
the admission, that though he was rewarded and promoted by the
government of the day, in consequence of the experiment, and
although the great usefulness of the contrivance in towing ships
out of port, &c., was admitted, yet it does not appear that a
second experiment was ever tried, much less that the machine was
ever brought into practical use.
SOLOMON DE CAUS, 1615.
(5.) Solomon De Caus was engineer and architect to Louis XIII.,
king of France, before the year 1612. In that year he entered the
service of the Elector Palatine, who married the daughter of King
James I., with whom he came to England. He was there employed by
the Prince of Wales in ornamenting the gardens of his house at
Richmond. [Pg018] During his sojourn in England he composed and
published at London, in the same year, a Treatise on Perspective.
This person was the author of a work entitled, "_Les Raisons des
Forces Mouvantes, avec diverses Machines tant utiles que
plaisantes_," which was apparently composed at Heidelburg, but
published at Franckfort, in 1615. The same work was subsequently
republished in Paris in 1623.
The treatise commences with definitions of what were then
considered the four elements: earth, air, fire, and water. Air is
defined to be a cold, dry, and light element, capable of
compression, by which it may be rendered very violent. He says,
"The violence will be great when water exhales in air by means of
fire, and that the said air is enclosed: as, for example, take a
ball of copper of one or two feet diameter, and one inch thick,
which being filled with water by a small hole, which shall be
strongly stopped with a peg, so that neither air nor water can
escape, it is certain that if we put the said ball upon a great
fire, so that it will become very hot, that it will cause a
compression so violent, that the ball will burst in pieces, with a
noise like a petard."
The effect which is here described is due to the combined pressure
of the heated air contained in the ball and the high pressure
steam raised from the water, but much more to the latter than to
the former. It is evident, however, from the language of De Caus,
that he ascribes the force entirely to the air, and seems to
consider that the force of the air proceeded from the water which
exhaled in it.
The first theorem is, "that the parts of the elements mix together
for a time, and then each returns to its place" (the elements here
referred to being apparently air and water). Upon this subject the
following is an example: "Take a round vessel of copper, soldered
close on every side, and with a tube, whereof one end approaches
nearly to the bottom of the vessel, and the other end, which
projects on the outside of the vessel, has a stop-cock; there is
also a hole in the top of the vessel, with a plug to stop it. If
this vessel will contain three pots of water, then pour in one pot
of water, and place the vessel on the fire about three or four
minutes, leaving the hole open; then take the vessel off the
[Pg019] fire, and a little after pour out the water at the hole,
and it will be found that a part of the said water has been
evaporated by the heat of the fire. Then pour in one pot of water
as before, and stop up the hole and the cock, and put the vessel
on the fire for the same time as before; then take it off, and let
it cool of itself, without opening the plug, and after it is quite
cold pour out the water, and it will be found exactly the same
quantity as was put in. Thus we see that the water which was
evaporated (the first time that the vessel was put on the fire) is
returned into water the second time when that vapour has been shut
up in the vessel, and cooled of itself."
In the description of these experiments, the processes of
evaporation and condensation are obscurely indicated; but there is
no intimation that the author possessed any knowledge of the
elastic force of steam. His theorem is, that the parts of the
element water mix for a time with the parts of the element air;
that fire causes this mixture, and that on removing the fire, and
dissipating the heat, then the parts of the water mixed with air
return to their proper place, forming again part of the water.
There is no indication of a _change of property_ of the water in
passing into vapour. It is difficult to conceive, if De Caus had
been aware that the vapour of water possessed the same violent
force which he distinctly and in terms ascribes to air, or if he
had been aware that in effect the vapour of the water produced by
the fire was a fluid, possessing exactly the same mechanical
qualities, and producing the same mechanical effects as air, that
he would not have expressed himself clearly on the subject.
He proceeds to give another demonstration that heat will cause the
particles of water to mix with those of air.
"After having put the measure of water into the vessel, and shut
the vent-hole, and opened the cock, put the vessel on the fire,
and put the pot under the cock; then the water of the vessel,
raising itself by the heat of the fire, will run out through the
cock; but about one sixth or one eighth part of the water will not
run out, because the violence of the vapour which causes the water
to rise proceeds from the [Pg020] said water; which vapour goes
out through the cock after the water with great violence. There is
also another example in quicksilver, or mercury, which is a fluid
mineral, but being heated by fire, exhales in vapour, and mixes
with the air for a time; but after the said vapour is cooled, it
returns to its first nature of quicksilver. The vapour of water is
much lighter, and therefore it rises higher," &c. &c.
In this second demonstration there appears to be some obscure
indication of the force of steam in the words "because of the
violence of the vapour which causes the water to rise," &c.
The fifth theorem is the following:—
"_Water will mount by the help of fire higher than its level_,"
which is explained and proved in the following terms:—
[Illustration: _Fig._ 2.]
"The third method of raising water is by the aid of fire. On this
principle may be constructed various machines: I shall here
describe one. Let a ball of copper marked A; well soldered in
every part, to which is attached a tube and stop-cock marked D, by
which water may be introduced; and also another tube marked B C,
which will be soldered into the top of the ball, and the lower end
C of which shall descend nearly to the bottom of the ball without
touching it. Let the said ball be filled with water through the
tube D, then shutting the stop-cock D, and opening the stop-cock
in the vertical tube B C, let the ball be placed upon a fire the
heat acting upon the said ball will cause the water to rise in the
tube B C."
In the apparatus as here described, the space enclosed in the
boiler above the surface of the water is filled with air. By the
action of the fire, two effects are produced: first, the air
enclosed above the water, being heated, acquires increased
elasticity, and presses with a corresponding force on the surface
of the water. By this means a column of water will be driven up
the tube A B at such a height as will balance the elasticity of
the heated air confined in the boiler; but besides [Pg021] this
the water contained in the boiler being heated, will produce
steam, which being mixed with air contained in the boiler, will
likewise press with its proper elasticity on the surface of the
water, and will combine with the air in raising a column of water
in the tube A B. In the above description of the machine, the
force which raises the water in the tube A B is ascribed to the
fire, no mention being made of the water, or of the vapour or
steam produced from it having any agency in raising the water in
the tube A B.
Antecedently to the date of this invention, the effect of heat in
increasing the elastic force of air was known, and so far as the
above description goes, the whole operation might be ascribed to
the air by a person having no knowledge whatever of the elasticity
of steam. M. Arago, however, who, on the grounds of this passage
in the work of De Caus, claims for him a share of the honour of
the invention of the steam engine, contends that the agency of
steam in this apparatus was perfectly known to De Caus, although
no mention is made of steam in the above description, because in
the second demonstration above quoted he uses the words, "the
violence of the vapour which causes the water to rise proceeds
from the said water; which vapour goes out from the cock after the
water with great violence." By these words M. Arago considers that
De Caus expresses the quality of elasticity proper to the vapour,
and that the context justifies the inference, that to this
elasticity he ascribed the elevation of the water in the tube C B.
There appears to be some uncertainty attending the birthplace of
De Caus. In the _Biographie Universelle_ he is said to have been
born and to have died in Normandy. M. Arago assigns Dieppe, or its
neighbourhood, as his birthplace.
There was another engineer and architect, Isaac De Caus, a native
of Dieppe, who published a work in folio, entitled "_Nouvelle
Invention de Lever l'Eau plus haut que sa Source, avec quelque
Machines mouvantes, par le Moyen de l'Eau, et un Discours de la
Conduite d'Icelle_." This volume is without a date, but from the
nature of its contents it would appear to have been published
before the work of Solomon De Caus already cited. The drawings and
machines described in both [Pg022] are exactly the same; but the
definitions and theorems quoted above on raising water by fire are
not given in the work of Isaac. It seems, therefore, that Solomon
De Caus re-published, with additions, the work of Isaac De Caus.
From the same birthplace being assigned to both these authors, as
well as from the similarity of their pursuits, it is likely they
were members of the same family, and from their christian names
they were probably Jews.
The work cited above, was dedicated to Louis XIII., and in the
dedication Solomon De Caus calls himself the subject of that
monarch; and in the privilege prefixed to the work he is
designated, "Our well-beloved Solomon De Caus, master engineer,
being at present in the service of our dear and well-beloved
cousin, the Prince Elector Palatine, has made known to us,"
&c.—"we, desiring to gratify the said De Caus, he being our
subject," &c.
It is therefore certain, whatever may have been the birthplace of De
Caus, that he was at least a subject of France. The circumstance of
his work being written in French, though published beyond the Rhine,
is also an argument in favour of his being a native of that country.
GIOVANNI BRANCA, 1629.
(6.) Giovanni Branca of Loretto in Italy, an engineer and
architect, proposed to work mills of different kinds by steam
issuing from a large æolopile, and blowing against the vanes of a
wheel. Branca was the author of many ingenious mechanical
inventions, a collection of which he dedicated to M. Cenci, the
governor of Loretto. These were published in a work printed at
Rome in 1629. It is a thin quarto, entitled "_Le Machine volume
nuovo, et di molto artificio da fare effetti maravigliosi tanto
Spiritali quanto di Animale Operatione, arichito di bellissime
figure. Del Sig. Giovanni Branca, Cittadino Romano. In Roma,
1629._" The work contains sixty-three engravings, accompanied by
descriptions in Italian and Latin. Branca's steam engine,
represented in the twenty-fifth plate, consists of a wheel
furnished with flat vanes upon its rim, like the boards of a
paddle wheel. The steam is produced in a close vessel, and made to
issue with violence from the extremity [Pg023] of a pipe directed
against the vanes, and causes the wheel to revolve. This motion
being imparted by the usual mechanical contrivances, any machinery
may be impelled by it. Different useful applications of this power
are contained in the work, viz. pestles and mortars for pounding
materials to make gunpowder, and rolling stones for grinding the
same; machines for raising water by buckets, for sawing timbers,
for driving piles, &c. &c.
This method of applying the force of steam has no analogy to any
application of steam in modern engines.
EDWARD SOMERSET, MARQUIS OF WORCESTER, 1663.
(7.) Of all the names which figure in the early annals of steam,
by far the most remarkable is that of the Marquis of Worcester,
who has left a description of a machine in a work, entitled "The
Scantling of One Hundred Inventions," which has been generally in
this country considered as giving him a right to the honour of
having been the inventor of the steam engine.
Lord Worcester having been engaged on the side of the Royalists in
the civil wars of the revolution, lost his fortune, and went to
Ireland, where he was imprisoned. He escaped from thence, and
reached France; from that country he ventured to London, as a
secret agent of Charles II., but was detected, and imprisoned in
the Tower, where he remained until the restoration, when he was
set at liberty. Tradition has connected the invention of the steam
engine with the following anecdote:—One day, during his
imprisonment, Lord Worcester observed the lid of the pot in which
his dinner was being cooked, suddenly forced upwards by the vapour
of the water which was boiling in it. Reflecting on this, it
occurred to him that the same force which raised the cover of the
pot might be rendered, when properly applied, a useful and
convenient moving power. After he recovered his liberty, he
accordingly proceeded to carry into effect this conception. The
contrivance to which he was ultimately led is described in the
following terms in the sixty-eighth invention, in the work above
named:—
"I have invented an admirable and forcible way to drive [Pg024]
up water by fire; not by drawing or sucking it upwards, for that
must be, as the philosopher terms it, _infra sphœrum activitatis_,
which is but at such a distance. But this way hath no bounder if
the vessels be strong enough. For I have taken a piece of whole
cannon whereof the end was burst, and filled it three quarters
full of water, stopping and screwing up the broken end, as also
the touch-hole, and making a constant fire under it; within
twenty-four hours, it burst and made a great crack. So that,
having a way to make my vessels so that they are strengthened by
the force within them, and the one to fill after the other, I have
seen the water run like a constant fountain stream forty feet
high. One vessel of water rarefied by fire driveth up forty of
cold water, and a man that tends the work has but to turn two
cocks; that one vessel of water being consumed, another begins to
force and refill with cold water, and so successively; the fire
being tended and kept constant, which the self-same person may
likewise abundantly perform in the interim between the necessity
of turning the said cocks."
Since the date of the publication of the "Century of Inventions"
was the year 1663, the experiments here mentioned must have been
made before that year. The description of the machine here given,
as well as others in the same work, was intended by the author,
not to convey a knowledge of the nature of the mechanism which he
used, but only to express the effects produced, and to indicate
the physical principle on which they depended. It should also be
observed, that an air of mystery was thrown by Worcester over the
accounts of all the machines which he described; and therefore any
obscurity in the above description ought not to be regarded as an
evidence against his claim to the discovery of the mechanical
agency of steam, so far as that agency is indicated by the effects
said by him to be produced. The above account is, however,
sufficiently distinct and explicit to enable any one possessing a
knowledge of the mechanical qualities of steam to perceive the
general nature of the machine described. To render this machine,
and that of De Caus, previously described, intelligible to those
who are not familiar with physical science, we must here explain
some general principles on which their agency depends. [Pg025]
(8.) Fluid bodies are of two kinds, inelastic fluids, or liquids,
and elastic fluids, or gases. Of the former of these classes,
water is the most familiar example, and of the latter, air.
These two species of fluids are each distinguished by peculiar
mechanical properties.
[Illustration: _Fig._ 3.]
(9.) The constituent particles of a liquid are distinguished from
those of solids by having little or no coherence; so that unless
the mass be confined by the sides of the vessel which contains it,
the particles will fall asunder by their gravity. A mass of
liquid, therefore, unlike a solid, can never retain any particular
form, but will accommodate itself to the form of the vessel in
which it is placed. It will press against the bottom of the vessel
which contains it with the whole force of its weight, and it will
press against the sides with a force proportional to the depth of
the particles in contact with the sides measured from the surface
of the liquid above. This lateral pressure also distinguishes
liquids from solids. Let us take for illustration the case of a
square or a cubical vessel, A B C D, _fig._ 3. If a solid body,
such as a piece of lead, be cut to the shape of this vessel, so as
to fit in it without pressing with any force against its sides,
the mechanical effect which would be produced by it when placed in
the vessel, would be merely a pressure upon the bottom, B C, the
amount of which would be equal to the weight of the metallic mass.
No pressure would be exerted against the sides; for the coherence
of the particles of the solid maintaining them in their position,
the removal of the sides would not subject the solid body
contained in the vessel to any change.
Now let us suppose this solid mass of lead to be rendered liquid
by being melted. The constituent particles will then be deprived
of that cohesion by which they were held together; they will
accordingly have a tendency to separate, and fall asunder by their
gravity, and will only be prevented from actually doing so by the
support afforded to them by the sides, [Pg026] A B, D C, of the
vessel. They will therefore produce a pressure against the sides,
which was not produced by the lead in its solid state. This
pressure will vary at different depths: thus a part of the side of
the vessel at P will receive a pressure proportional to the depth
of the point P below the surface of the lead. If, for example, we
take a square inch of the inner surface of the side of the vessel
at P, it will sustain an outward pressure equal to the weight of a
column of lead having a square inch for its base, and a height
equal to P A. And, in like manner, every square inch of the sides
of the vessel will sustain an outward pressure equal to the weight
of a column of lead having a square inch for its base, and a
height equal to the depth of the point below the surface of the
lead.
(10.) We have here proceeded upon the supposition that no force
acts on the upper surface A D of the lead. If any force presses A
D downwards, that force would be transferred to the bottom by the
lead, and would produce a pressure on the bottom B C equal to its
own amount in addition to the weight of the lead; and if the lead
were solid, this would be the only additional mechanical effect
which such a force acting on the surface A D of the lead would
produce. But if, on the other hand, the lead were liquified, then
the force now adverted to, acting on the surface A D, would not
only produce a pressure on the bottom B C, equal to its own amount
in addition to the weight of the lead, but it would also produce a
pressure against every part of the sides of the vessel, equal to
that which it would produce upon an equal magnitude of the surface
A D.
Thus if we suppose any mechanical cause producing a pressure on
the surface A D amounting to ten pounds on each square inch, the
effect which would be produced, if the lead were solid, would be
an additional pressure on the base B C amounting to ten pounds per
square inch. But if the lead were liquid, besides this pressure on
each square inch of the base B C, there would likewise be a
pressure of ten pounds on every square inch of the sides of the
vessel.
All that has been here stated with respect to a square or a
cubical vessel will be equally applicable to a vessel of any other
form. [Pg027]
(11.) The second class of fluids are distinguished from liquids by
the particles not merely being destitute of cohesion, but having a
tendency directly the reverse, to repel each other, and fly
asunder with more or less force. Thus if a vessel, such as that
represented in _fig._ 3., were filled with a fluid of this kind,
being open at the top, and not being restrained by any pressure
incumbent upon it, the particles of the fluid would not rest in
the vessel by their gravity, as those of the liquid would do; but
they would, by their mutual repulsion, fly asunder, and rise out
of the vessel, as smoke is seen to rise from a chimney, or steam
from the spout of a kettle. Let us suppose, then, that the vessel
in which an elastic fluid is contained is closed on every side by
solid surfaces. In fact, let us imagine that the square or cubical
vessel represented in _fig._ 3. is closed by a square lid at the
top A D, having contained in it an elastic fluid, such as
atmospheric air.
If such a cover, or lid, had been placed upon a liquid, the cover
would sustain no pressure from the fluid, nor would any mechanical
effect be produced, save those already described in the case of
the open vessel; but when the fluid contained in the vessel is
elastic, as is the case with air, then the elasticity (by which
name is expressed the tendency of the particles of the fluid to
fly asunder) will produce peculiar mechanical effects, which have
no existence whatever in the case of a liquid.
It is true that, supposing the fluid to be air or any other gas or
vapour, a pressure will be produced upon the bottom B C of the
vessel equivalent to the weight of such fluid, and lateral
pressures will be produced on the different points of the sides by
the weight of that part of the fluid which is above these points;
but gases and vapours are bodies of such extreme levity, that
these effects due to their weight are neglected in practice.
Putting, then, the weight of the air contained in the vessel out
of the question, let us consider the effect of its elasticity. If
the vessel, as already described, be supposed to contain
atmospheric air in its ordinary state, the tendency of the
constituent particles to fly asunder will be such as to produce on
every square inch of the inner surface of the vessel [Pg028] a
pressure amounting to fifteen pounds; this pressure being, as
already stated, quite independent of the weight of the air. In
fact, this pressure would continue to exist if the air contained
in the vessel actually ceased to have weight by being removed from
the neighbourhood of the earth, which is the cause of its gravity.
(12.) Different gases are endowed with different degrees of
elasticity, and the same gas may have its elasticity increased or
diminished, either by varying the space within which it is
confined, or by altering the temperature to which it is exposed.
If the space within which an elastic fluid is enclosed be
enlarged, its elasticity is found to diminish in the same
proportion. Thus if the air contained in the vessel A B C D
(_fig._ 3.) be allowed to pass into a vessel of twice the
magnitude, the elasticity of the particles will cause them to
repel each other, so that the same quantity of air shall diffuse
itself throughout the larger vessel, assuming double its former
bulk. Under such circumstances, the pressure which it would exert
upon the sides of the larger vessel would be only half that which
it had exerted on the sides of the smaller vessel. If, on the
other hand, it were forced into a vessel of half the magnitude of
A B C D, as it might be, then its elasticity would be double, and
it would press on the inner surface of that vessel with twice the
force with which it pressed on that of the vessel A B C D.