APPENDIX.
A CONCISE history of the Steam Engine, from its first discovery to the present day, will perhaps be accept able and useful to those who may not have an opportunity of reading the Encyclopedia, or other rare and expensive philosophical works, where a fuller account thereof is to be found. It may also excite the curiosity of ingenious young men to procure those works and read them; and to acquire a knowledge, which may qualify them to be more useful to their country.
"The steam engine was beyond all doubt invented by the Marquis of
Worcester during the reign of Charles II. This nobleman published, in 1663,
a small book intitled A CENTURY OF INVENTIONS; giving some obscure and enigmatical
account of a hundred discoveries or contrivances of his own, which he extols
as of great importance to the public. He appears to have been a person of
much knowledge and great at ingenuity: but his description or accounts of
these inventions seem not so much intended to instruct the public, as to
raise wonder; and his encomiums on their utility and importance are to a
great degree extravagant.* His ac-
* He was perhaps as capable of invention as any man ever was, Suid we think him extravagant, only because we (do not understand him. The human mind seems incapable of believing any thing that it cannot conceive and understand to be possible, excepting what respects the dogmas of religion, to which we often yield implicit faith, without inquiring into the possibility or even probability tbereof. I speak from experience; 10' when it was first asserted that merchant flour mills could be constructed to attend themselves, so far as to take the meal from the stones and this wheat from the waggon, and raise them to the upper stories, spreadingthe meal to cool, and gathering it by the same operation into the bolting hopper, to be bolted, etc etc. until the flour was ready for packing; the projector was answered, " You cannot make water run up hill, you cannot
make wooden millers." It was thought impossible, and the inventor to be as wild in his idea', and his assertions as extravagant as any of the Marquis of Worcester's ,' Century of Inventions," are now believed to be: but we are now forced to acknowledge, that what he said concerning the steam engine, was trade, as well as of the telegraphe, the conversive statue, &C and in proportion as we understand him, and see his inventions in operation, we will believe, and cease to charge him with having been extravagant in his encomiums on their importance and utility,
I beg leave to differ with the writer, in his assertion that the Marquis's
description of his steam engine, is not sufficiently clear and explicit,
so as to enable an ingenious workman to discover its principles, construct
an engine and put it in practice.
shovel which scoops it up. B the edge of the shovel, made of sheet-iron,
4 feet wide, strengthened by a steel plate in front 8 inches wide. R a piece
of timber to strengthen the shovel. Q one of the hind wheels. F one of the
handles. G a treadle. H a chain connecting the treadle to the handle. I
one of the iron bars connecting the shovel to the axle of the fore wheels
L.
THE OPERATION.
The cattle are hitched to the bars I, and the man at the handles guides the point of the shovel B between the solid and loose earth to scoop up a load, driving a quantity before the shovel. If the load proves too heavy he puts his foot on the treadle and raises the point of the shovel B a little, which causes it to drop part of the load, especially in hollow places; and when the machine arrives at the place where the load is to be deposited, he throws up the handles suddenly which drives the shovel into the solid earth, and the force of the cattle turns the shovel over, bottom up, the bar N to rest on the iron bars I, and discharges the load. The shovel remains in this position, the bars 0 sliding on the ground, until the machine arrives at the place to take up another load, when by the rope P the shovel is drawn to its proper position. It will load and discharge two loads a minute by the force of cattle.
count, however, of the steam engine, although by no means fit to give
us any distinct notions of its structure and operation, is exact as far
as it goes, agreeing precisely with what we now know of the subject. It
is No.68 of his inventions. His words are as follow: ' This admirable method
which I propose of raising water by the force of fire has no bounds if the
vessels be strong enough: for I have taken a cannon, and having filled it
4ths full of water, and shut up its muzzle and touch-hole, and exposed it
to the fire for 24 hours, it burst with a great explosion. Having afterwards
discovered a method of fortifying vessels internally, and combined them
in such a way that they filled and acted alternately, I have made the water
spout in an uninterrupted stream 40 feet high; and one vessel of rarefied
water raised 40 of cold water. The person who conducted the operation had
nothing to do but turn two cocks; so that on vessel of water being consumed,
another begins to force, and then to fill itself with cold water, and so
on in succession.'* It does not appear that the noble inventor could ever
interest the public by these accounts."
OF CAPTAIN SAVARY'S STEAM ENGINE.
" CAPTAIN SAVARY, a gentleman of great ingenuity and ardent mind, saw the reality and practicability of the Marquis of Worcester's project. He knew the great expansive power of steam, and had discovered the inconceivable rapidity with which it is reconverted into water by cold; and he then contrived a machine for raising water, in which both of these properties were employed. He obtained his patent after having actually erected several machines, of which he gave a description in a book intitled THE MINER's FRIEND, published in 1696, and in another work published in 1699. Much about this time Dr. Papin, a Frenchman and fellow of the Royal Society, invented a method of dissolving bones and other animal solids in water, by confining them in close vessels, which he called DIGESTERS, so as to acquire a great degree of heat."
"We may add, that much about the same time Mr. Amontons contrived
a very ingenious but intricate machine, which he called a fire-wheel.
It consisted of a number of buckets placed in the circumference of a
wheel, and communicating with each other by very intricate circuitous passages.
One part of this circumference was exposed to the heat of a furnace, and
another to a stream or cistern of cold water. The communications were so
disposed, that the steam produced in the buckets on one side of the wheel
drove the water into the buckets on the other side, so that one side of
the wheel was always much heavier than the other; and it must therefore
turn round, and may execute some work. The death of the inventor, and the
intricacy of the machine, caused it to be neglected.* Another member of
the Parisian
In the year 1791 or 1792, I met with a description of the principles and operation of that curious toy, called the pulse glass. I saw in it principles which I conceived might be applied to mechanical purposes, for raising water or tunling mills. I set my mind immediately to discover
force of the vapour was employed; but it met with no encouragement. The English engineers had by this time so much improved Savary's first invention, that it supplanted all others. We have therefore no hesitation in giving the honour of the first and complete invention to the Marquis of Worcester; and we are not disposed to refuse Captain Savary's claim to originality as to the construction of the machine, and even think it probable that his own experiments made him see the whole independent of the Marquis's account."
Captain Savary's engine, as improved and simplified by himself, is as follows.
It consists of a strong copper boiler, properly built up in a furnace; a receiver in which he formed a vacuum, by expelling the air with steam which was then condensed; a pipe descending from the bottom of the receiver to the water in the well; another pipe ascending to the reservoir into which the water is to be raised; a steam pipe leading from the top of the boiler into the top of the receiver, in which pipe is a cock, which being turned lets the steam rush into the receiver, to drive out the air through a valve inserted in the rising pipe; then a jet of cold water is let out of the rising pipe into the receiver, to condense the steam and form a 'vacuum, which being done, the pressure of the atmosphere presses the water in the well up the lower pipe, and fills the receiver, which is prevented from returning to the well, by the shutting of a valve fixed in the pipe. The steam cock being again turned, lets the steam press on the surface of the water in the receiver, and forces it up the rising pipe into the reservoir; another jet of cold water let into the receiver, forms a vacuum, and the water rises from the well to fill the receiver again, &c. It is hardly necessary to mention, that the top of this receiver must always be within less than ~3 feet of the surface of the water in the well, or else the pressure of the atmosphere will not force the water up into it. The contrivance is ingenious.
academy of sciences (Mr. Deslandes) also presented to the academy a project
of a steam wheel, where the impulsive
the means of application. After being engaged in this study, at leisure hours, for 9 years, and having formed a great variety of plans, of which none appeared sufficiently simple, to he worthy of experiment, I conceived the idea of a hollow wheel, to be made of metal, and filled about half fill with spirits of wine, or 'water. After expelling the air sn as to form a vacuum 'ii the upper part of the wheel, it must he closed up tight, so as neither to emit air, nor emit steam. There are no working cocks or valves, or moving parts, excepting the axle on which it is hung ~d which turns out its godgeons like those of the water-wheel of a mill. This wheel being set over a fire, with the flue confined, so as to embrace about 14th part of its circumference, will turn round with a very low degree of heat, on the principles of the pulse glass, but it is then weak in power. The heat of the fire generating steam in the lower and rising quarter of the wheel, forces the liquid to the descending and upper quarter of the wheel, and it turns ro'ind slowly, by the weight of the water, being greater in the descending than in the ascending side of the wheel. I suppose it would produce no effects worthy of notice, on this principle alone. But when I apply, in addition thereto, my new principle of confining and retaining the steam, and increasing the heat, thereby to increase the elastic power of the steam, in a rapid ratio, and by applying a small slower of cold water to the top of the wheel, to condense the steam there a little, say 30 degrees, from 272 to 2420 the power of the steam in the lower quarter of the wheel will he 60 pounds to the inch, and in the upper quarter reduced to 30 pounds; the one being double the other the greater will overpower the lesser, and drive the water with great velocity from the lower to the upper quarter of the wheel, and it will move round rapidly with great power, and perform much work. I constructed a wheel of lead to work on these principles, which moved slowly, agree ably to my calculations; I have therefore no doubt, of the operation of the principles. Considering its great simplicity, having excepting the gudgeons, no working or wearing parts; that being once filled with spirits of wine, which would require much less fuel than water, it requires no supply; that 55 no vapour is suffered to escape the spirits could not diminish in the wheel, I think it the simplest and perhaps most philosophical steam engine ever conceived. Although it would he expensive to erect in the first place, it might excel all others, ever yet constructed. I am however satisfied with what I have already in use; but if I expected to live 100 years longer, and could spare the money and time, I would think it worthy of a 1011 experiment. I have specified it, and described drawings thereof, which I have filed in the patent office, that it may not be lost.
density of a vacuum being speedily formed, and a piston of a projected machine, which was to propel a piston by means of air, took the hint and conceived the idea of forming this vacuum by means of steam, which gave rise to his celebrated engine that was wrought by the weight of the atmosphere. He constructed an engine consisting of a large boiler, properly set in a furnace, a little above which he set a cylinder, nicely bored and polished smooth within, and fixed a piston air-tight to move up and down therein; the piston was suspended to one end of a lever or working beam, and the pump rod was suspended at the other end, and was considerably heavier than the piston so as to draw it up to the top of the cylinder. The steam being let from the boiler by turning a cock or the like into the lower end of the cylinder, filled it with steam, which being lighter than the air drove the air all out at a small valve or clack fixed at the bottom of the cylinder for that purpose. This done, a jet of cold water was let into the cylinder, to rise through its bottom and strike against the underside of the piston, and falling in a spray dispersed over the inside of the cylinder instantly condensed the steam, forming a vacuum under the piston in the cylinder; when the pressure of the atmosphere on its upper side, about 15 pounds to the inch, being no longer balanced by air nor steam below, acted as the power to drive the piston to the bottom, drawing up the pump rod, to make a stroke. At the instant the engineer saw the piston arrive at the bottom of the cylinder, he opened the steam pipe to let the steam from the boiler into the cylinder, to balance the weight of the air on the piston; the superior weight of the pump rod at the other end of the lever beam, raised the piston to the top of the cylinder, when a jet of cold water was let in again to condense the steam, to form a vacuum, produce another stroke, and so on. 'this engine was offered to the public in 1705, but many difficulties occurred in the execution which were removed one by one, an4 it was it not until the year 1712 that the
1:3
But the great defect of this machine, is the prodigious waste of steam, and consequently of fuel; for the steam at every stroke comes in immediate contact with the cold surface of the water, and cold top and sides of the cylinder; and daily experience shows, that a few scattered drops of cold water will condense a great quantity of steam, almost instantaneously; by some experiments, frequently repeated, by the writer of this article, it appears, that no less than 1555 of the whole steam is uselessly condensed in this manner, and not more than ~1 is employed in allowing the water to descend by its own weight, to run out of the receiver; and he has reason to think that the portion thus wasted will be considerably greater if the steam be employed to force the water out of the receiver to any considerable height."*
Numerous attempts have been made to diminish this waste, but all to little
purpose. Mr. Blackey has attempted to lessen it, by using two receivers;
in the first was oil, and into this only the steam was admitted; this oil
passed to and fro between the two receivers, and never touched the water
except on a small surface, but this hardly produced a sensible diminution
of the waste. This was done about the year 1700.
OF NEWCOMEN'S ATMOSPHERIC STEAM ENGINE.
MR. NEWCOMEN, an ingenious blacksmith of Cornwall, a person of some reading, who was particularly acquainted with the writings and projects of his countryman, Doctor Hooke, and with the principles and construction of captain Savary's steam engine, is supposed to have improved on some hints given him by Dr. Hooke, respecting the himself the writer had taken into consideration, the rapid ratio of the decrease of the elastic power of the steam as the heat is diminished, he could have entertained no doubt but that the waste of power is far greater than he has stated it to be, perhaps not less than nineteen-twentieths
water cooling the cylinder, which having to be heated up at every stroke, condenses a great part of the steam. We have frequently attended to measure the weight of the steam which filled a very light vessel, that held 12,600 grains of water, and found it always less than one grain. So that we have no doubt of its being much more than 10,000 times rarer than water. Desaugulier says, it is 14,000 times rarer than water, and from some experiments to ascertain the water used at each stroke of the engine, we may safely suppose, that only + of the steam is employed in allowing the piston to rise, the remaining '~ being employed to warm the cylinder. The great obstacle to its extensive use, i~ the expense of fuel; an engine having a cylinder 4 feet diameter working night and day, consumes about 3400 chaldrons (London) of coals per year, or about 400 bushels per day.
To lessen this expense "every one had his particular nostrum for
the construction of his furnace, and some were undoubtedly more successful
than others. But science was not yet sufficiently advanced: it was not till
Dr. Black had made his grand discovery of latent heat, that we could know
the intimate relation between the heat expended in boiling off a quantity
of water and the quantity of steam that it produced."
OF JAMES WATT'S IMPROVEMENTS ON THE STEAM ENGINE.
ABOUT the time of the discovery of latent heat by Dr. Black, in 1763, Mr. James Watt, a man of a truly philosophical mind, eminently conversant in all branches of natural knowledge, and the pupil and intimate friend of Dr. Black, was amusing himself with repairing a working model of the steam engine, belonging to the philosophical apparatus of the university, the thought occurred to him to attempt the condensation of the steam in a vessel separate from the cylinder.
This he found to succeed beyond his most sanguine expectations, and proved a great saving of steam, consequently
engine seemed to give confidence in its efficacy. The most exact and unremitting attention of the manager was required to the precise moment of opening and shutting the cocks, as neglect might be ruinous. At last, in 1717, Mr. Beighton, a very ingenious and well-informed artist, simplified the whole of the subordinate movements, and brought the machine into the form in which it has continued without the smallest change, until the present day.
We now see the great difference between Savary's and Newcomen's engine
in respect of principle. Savary's was really an engine which raised water
by the force of steam; but Newcomen's raises water entirely by the pressure
of the atmosphere, and steam is employed merely as the most expeditious
method of producing a void, into which the atmospherical pressure may impel
the first mover of his machine. The elasticity of the steam is not
the first mover.* This engine still laboured under the great disadvantage
of great waste of the steam, occasioned by the injection of
This invention and discovery of Newcomen's, made from the hint given by doctor Hooke, in 1705, just 100 years ago, was the first step (an enormous stride) from the simple path of nature Here they lost sight of the true principle discovered by the Marquis of Worcester, be-fore they had gained sufficient knowledge thereof, to enable them to apply it to a useful purpose; and wandering ever since have had faint glimpses of it, but have never returned to the true path. Had Newcomen constructed a strong boiler, such as used by Savary, and applied the force of his steam simply to lift the piston, and the piston to lift the pump-rod to make the stroke, and let his steam escape uncondensed, lie would have performed at least ireple the work with the same fuel, with out endangering the bursting of his boiler. But finding his engine, be it improved, so far to excel Captain Savary's for most purposes; having got clear of the great difficulties which Savary laboured under, occasioned by his losing almost all his power after he had generated more than sufficient, had it been rightly applied ; having established tables and rules for constructing and proportiolling the engine to the task assigned to it; and finding it extolled as the greatest discovery ever made in the art, was indeed not to be expected that any person under such weighty incumbrances could ever return to the true path. It was only to be expected from one who unincumbered by scientific shackles, was fret to go as nature guided.
It may not be here improper to state the actual performance of some of these engines, as they have been ascertained by experiment.
An engine having a cylinder of 31 inches in diameter, and making 17 douse strokes per minute, performs the work of forty horses working night and day (for which three relays or 120 horses must be kept,) and burns 11,000 pounds of Staffordshire coal per day.* A cylinder of 19 inches, making 25 strokes of 4 feet each per minute, performs the work of 12 horses working constantly, and burns 3700 pounds of coals per day.** A cylinder of 24 inches, making 22 strokes of 5 feet, burns 5500 pounds of coals, and is equivalent to the constant work of 20 horses. And the patentees think themselves authorised by experience to say in general, that these engines will raise more than 20,000 cubic feet of water 24 feet high for every hundred weight of good pit coal consumed by them."
Mr. Watt, among his first speculations on the steam engine, made some
attempts to produce an immediate circular motion. One in particular was
uncommonly ingenious. It consisted of a drum turning air-tight within another,
with cavities so disposed that there was a constant and great pressure urging
it in one direction. But no packing of the common kind could preserve it
air-tight with sufficient mobility. He succeeded by immersing it in mercury,
or in an amalgam which remained fluid in the heat of boiling water; but
the continual trituration soon calcined the fluid and rendered it useless.
He then tried Parent's or Dr. Barker's mill, inclosing the arms in a metal
drum, which was immersed in cold water. The steam rushed rapidly along the
pipe which was the axis, and it was hoped that a great reaction would have
been exerted at the end of the arms; but it was almost nothing. The reason
seems to
Which is about 83 pounds, or about 1 bushel of coals to do the work of a horse.
Which is about 102 pounds of coals to do the work of horse. Which is 91 pounds of coals to do the work of a horse.
of fuel; but he was obliged to extract the air from the con denser, by a small pump, to keep up the vacuum, as all water produces more or less air by boiling. His next improvement was to obtain a double stroke, up as well as down. To effect this, he shut up the upper end of the cylinder, passed the piston rod through a stuffing box made air-tight, and introduced the steam above the piston to press it down as well as up instead of the atmosphere. The steam escaped by pipes leading from each end of the cylinder into the condenser, and shutting the atmosphere totally from the inside of the cylinder proved a further saving, as the cylinder remained hot, and did not condense the steam. These are his principal improvements. Many difficulties occurred in the execution, which his fertile mind surmounted as they occurred. He made great improvements in the form of furnaces and boilers, and many others in the subordinate movements, so as to render the machine applicable to most purposes, far more easily governed, capable of being varied in power, to suit any task assigned to it, and as regular in its operations as a water-wheel. " In the engine in its most perfect form, there does not seem to be above -41 part of the steam wasted, in heating the apparatus, so that it is not possible to make it ~ part more powerful."*
The fact is that an engine of this construction, of the same dimensions
with a common engine, making the same number of strokes of the same extent,
does not consume above 45- part of the fuel that is consumed by the best
engines of the common form.
It is evident that when the writer said, '~ that it is not possible to make it one-fourth more powerful," he had no knowledge of the great saving of fuel and increase of power, that would he the result of onfluing the steam, and increasing the heat and elasticity of the steam; or of applying this great elastic power, to propel the piston, by which the power may he increased tenfold, and the fuel be reduced to one-third to perform equal work; yet it seems that this same writer gives the set of experiments which ascertains the Caistence Of the principle
be, that the greatest part of the steam was condensed in the cold arms. It was then tried in a drum kept boiling hot; but the impulse was now very small in comparison with the expense of steam. This must be the case."*
Steam having no weight we cannot expect it to re-act with much force,
by issuing from the rotary tube. This is the reason it produces so little
power in this application. I therefore have contrived a steam engine wherein
the elastic power of the steam is to force oil or quicksilver (if any means
can be discovered to keep it fluid) through the rotary tube; when the engine
will work with great power, and produce an immediate rotary motion. I have
also contrived two forms of wheels, not before mentioned, making five different
forms; all of which I have specified and explained by drawings, &c.
according to law, as different modes in which I contemplate using my principle,
of confining and retaining the steam and increasing the heat, to increase
the elastic power of steam, for the purpose of saving fuel, and lessening
the expense of constructing engines, none of which 'will ever be worth notice
without said principle. But on mature deliberation I have reason to conclude
that none of them will ever excel the cylinder and piston, so far as to
be worthy of my time and attention to put them in operation.
It is evident from this account that Mr. Watt, in these experiments, has used weak steam, and placed dependence on the use of a condenser. Had he in his experiment with Dr. Barker's mill, lessened the apertures by which the steam issued, 50 as to confine the steam until the power in the boiler was equal to 100 pounds to the inch, lie would have been astonished, to see it revolve about 1000 times in a minute, supposing the rotary tube to have been 3 feet in length. I have tried the same experitment, but without the least hope of success, on any other principle than by confining the steam to increase its elasticity, to a great degree My rotary tube was 3 feet long, the elastic power of the steam about 56 pound to the inch. It revolved with a velocity of about 700 or 1000 times per minute. The apertures by which the steam issued, about 2-hathes of an inch diameter. It exerted more than the power of two men, and would answer to turn, lathes, grindstones, &C where fuel is very cheap. I have specified and explained it in die patent office.
I here close my extracts from the Encyclopedia, as my limits will not
admit of doing justice to the merits of the different inventors and improvers
of steam engines ; and I must refer the readers to the work itself, where
they may expect to be both pleased and edified, if they wish to understand
fully, the most philosophical and useful machine ever invented.
OF LATE INVENTIONS OR IMPROVEMENTS
ON STEAM ENGINES.
A man's useful inventions, subject him to insult, robbery, and abuse.
FRANKLIN.
THE truth of the above observation is daily verified. No man ever made a useful discovery, invention, or improvement, to which he claimed exclusive right, under the protecting laws of his country and was permitted to enjoy such right peaceably. He may expect to be attacked by a host of claimants, who to support their claims, load the inventor with heavy abuse, and he is obliged at great expense to defend himself.
The author when a boy, was led to the study of the possibility of moving land carriages without animal force, which he viewed as a very desirable object. He had heard of various attempts having been made, by means of cranks, wheels, pinions, springs, wind, &c. all of which appeared to him as too futile to be worthy of attention, from the want of original power. Instances had occurred, of the great explosions made by a small quantity of water confined in the breech of a gun-barrel, exposed to a smith's fire. Ilere he saw original power, which he conceived to be unlimited, but had formed no idea of the means of its application, until he met with a description of an atmospheric steam engine.
He was astonished to find that the steam, was not applied as the prime mover, but only as the means to form a vacuum, to apply the weight of the atmosphere. This he conceived to be a great error, and the more he investigated the subject, the more he was confirmed in this opinion; for it appeared clear to him, that the elastic power of the steam rose in some rapid ratio compared with the increase of heat, otherwise the power could not he augmented in so short a time, to a degree sufficient to make explosions equal to gun-powder. He conceived that double heat in the water did produce 8, 10, 16, or 32 times the power of steam, and perhaps more. These ideas existed some years before he conceived the plan of constructing small engines, to be moved by this irresistible power, to work with steam equal in power to 10 atmospheres, that would be capable of moving land carriages with heavy burdens. Not satisfied with the cylinder and piston, because it did not produce an immediate circular motion, he endeavoured to discover means of applying the expansive power of steam to a wheel, which he matured in 1784. This wheel is now described in the patent office, and called his Circular Steam Engine, No.2. He was then confident that he could propel, by means of steam, land carriages and boats to great advantage:
but as the expense was very considerable, in the first instance, he explained the principles to every person with whom he conversed on the subject, in order to induce some one or other to join him in the enterprise. Having matured his improvements on merchant flour mills, he applied to the state legislatures of Pennsylvania and Maryland for exclusive rights, and included in this application the right of propelling land carriages, by the power of steam, and the pressure of the atmosphere. Boats were not included; supposing the exclusive right in those states was not worth obtaining. Pennsylvania granted for the mill improvements only, Maryland for both mill improvements and land crriages-. While waiting on the legislature of Maryland, he
was introduced to a gentleman, (Mr. Masters) an old sea-captain, who had obtained the name of a projector, by having contrived a machine to draw trees up by the roots, which was found not to answer well in this country. This gentleman was possessed of a philosophical and mechanical genius, and was extremely anxious to be acquainted with the principles of the engine, that was to propel land carriages and boats. They. were made known to , and he expressed his approbation by saying, that a large engine on those principles would be useful if applied on board a ship crossing the Atlantic, to increase her despatch, in cases of emergency, by being used in calms, and during head winds. He said he was going to England in a short time, and asked permission of the inventor to explain the principles of his engine to people there Many other instances occurred, by which the principles of the invention might have been early communicated to English engineers. Drawings and explanations nations were sent to them, but it seems they were satisfied that they had arrived at the utmost possible state of perfection, and were therefore not easily moved.
Although the inventor had obtained a patent of the state of Maryland, before the United States' government was authorised to grant patents, he was so engaged with the introduction of his mill improvements, that he could not prosecute his inventions on steam engines, further than filing drawings and specifications of the principles in the patent office in 1792, and trying some experiments which confirmed him in his principles. In the year 1801 he commenced the execution of an engine, and in the winter of 1802, got it in full operation. Its performance excited considerable attention and curiosity.
On the day of Doctor Coxe of Philadelphia called on him with a letter from John Stevens, Esq. of Hoboken, New-Jersey, dated Feb. 7, 1804, propounding a number of questions, respecting the principles and construction of the engine, which he had heard was so powerful as to do the
great work that had been stated in newspapers which had fallen into Mr. Stevens's hands. After having received assurances, that Mr. Stevens intended no interference with the inventor, he proceeded to answer all his questions, and to explain the principles and construction of his engine, as fully and freely as he had done to any other person; all which Dr. Coxe thinks he communicated in his answer to Mr. Stevens, as far as his memory and short pencil notes enabled him to do. Some time after this Dr. Coxe called again with another letter from the said Stevens, dated February 16, 1803, propounding another list of questions, which, after similar assurances being given, that no interference was intended, nor need to be feared, were answered, and the whole of the principles explained. Dr. Coxe called at two other different times on the same subject, and the inventor is free to say, that to no gentleman whatever, (excepting only Mr. Charles Taylor, steam engineer, and Mr. Robert Patterson, professor of mathematics in the university of Pennsylvania) has he explained the principles of his invention with more care and exactness than he did to Dr. Coxe. This he was the better able to do, having before that time committed the whole thereof to writing, from which he has since compiled his new work on steam engines. In the month of January, 1805, he laid the following
printed circular letter before the members of congress:
THE subscriber with diffidence presumes to lay before the honourable Senators and Representatives in Congress, individually, (hoping it may be well received) the following concise description of the principles of Steam Engines.
The present English steam engine, so much celebrated, consisted, in it first state, of a boiler to generate the steam; to which was connected a cylinder, open at top, in which a piston moved up and down, which was attached to a working beam, hung on its centre, the other end of which was
connected to a pump. The steam was let into the cylinder below the piston, to balance the atmosphere; and the weight of the pump rod, at the opposite end of the beam, raised the piston up to the top of the cylinder; the steam was then shut off; and a jet of cold water let into the cylinder, to condense the steam, and form a vacuum under the piston in the cylinder.; and then the weight of the air on the top of the cylinder, which is l5lbs. to every square inch of its area, being no longer balanced, was the power which drove down the piston and drew up the pump rod to make a stroke. If they could have made a perfect vacuum by these means, the power of the engine would have been 1 15lbs. to every inch area of the piston; but it was found not to exceed 81lbs. and required large quantities of fuel, great part of the steam being lost in heating up the cylinder at every stroke, which was cooled by the jet of cold water. This is called the single-stroke engine.
The celebrated James Watt improved this engine, by making his steam of power equal to the weight of the atmosphere, and letting it in at the top of the cylinder, to supply the place of the atmosphere to push down the piston, while the steam was condensed below, and also at the bottom, while condensation was going on above, making a double stroke; and to avoid the loss occasioned by the jet cooling the cylinder, he led the steam off from each end of the cylinder into a seperate vessel, into which he let the jet of cold water to condense the steam. He found by these means he could make a more perfect vacuum, and computed the power of his engine at between 11 to l3lbs. to the inch. The expense of fuel was greatly less'ned.
This is Watt's double-stroke steam engine, so celebrated and very justly deemed the greatest of all human inventions. Although it be so limited in its power, to double the power they make an engine of double capacity, and it requires double fuel, This engine labours under the following disadvantages:
There is a continual accumulation of air in the condenser
not even suggested that this principle might be applied to any use,) which ratio, continued from 212 to 424 degrees double heat in the water, gives 128 times the power of steam; and it is absurd to suppose that it would require 128 times the fuel to be expended in an equal time to produce double heat in the water; and if not, then this new principle will require less fuel to produce equal power.
To apply this wonderful principle, I construct my boilers of circular cylindric forms of small diameters, the best possible form to contain a great elastic power; and to enlarge their capacity, I extend their length or increase their number, which also gives a large surface for the fire to act on, making them sufficiendy strong to contain steam of elastic power equal to 15001bs. to the inch area of the piston, which would give my engine 100 times the greatest possible power of the English principle: but at the same time arranging the work so that 50lbs. to the inch power will be sufficient in ordinary cases, and so that we cannot without considerable trouble and difficulty, ever raise the powers to exceed 150lbs. to the inch in the most extraordinary case; greater power we will never want, which makes the engine perfectly safe from explosion, as it will bear from 10 to 30 times the power that we shall ever have need of using, and be from 5 to 10 times as powerful as Watt's engine. I have an engine in operation in the most simple form without a condenser, which is capable of performing three times the work with equal fuel, compared with the English engine; and succeeds according to theory, working with steam, generally equal in power from 50 to 1001bs. to the inch; doubling the fuel appears to produce about 16 times the power and effect. Its great power and simple structure fits it for propelling boats up the Mississippi, and carriages on turnpike roads, two of the most difficult applications; therefore will apply to all others as a powerful agent.
I have conceived further, and still greater improvements, which I wish to put in operation.
generated by boiling the water, which would destroy the vacuum in a short time, and stop the engine; therefore an air pump is constantly at work to extract it. Also a continual accumulation of sediment, which adheres to the bottom of the boiler, forming a non-conductor of heat, causing the boiler to burn out; they are obliged to stop once or twice a month, let all cool, and open the boiler to go inside to scrape away the sediment.
The boilers are constructed to bear little or no power of steam, their principle being to make the steam inside the boiler equal to the atmosphere outside; and if ever the safety-valve is overloaded, or a double weight laid on by accident, and the steam does not get vent, the boiler explodes; and if ever the steam in the boiler is suddenly condensed by a dash of cold water on its top, &c. it collapses, being pressed in by the weight of the atmosphere. The principles of the engine are dangerous, ever liable to these accidents, and it was generally believed that nothing could be gained by increasing the power of the steam to exceed atmospheric power.
My ideas of the application of the power of steam were very different at the first. I conceived the power to be irresistible; that the power increased in some very rapid ratio, as we increased the heat in the water; otherwise it could not rise to such a pitch in so short a time, as to make the terrible explosions which I had known of: I supposed that doable heat in the water, would give eight, or sixteen, or perhaps thirty-two times the power of steam. On these principles I conceived that I could obtain any power I pleased, simply by confining the steam and increasing the heat, and perhaps with less fuel, and a much smaller engine. After I had commenced the construction of an engine on these new principles, I was informed that some curious and philosophic gentlemen had made a set of accurate experiments, the result of which was that every addition of thirty degrees of heat to the water by Fahrenheit's thermometer, be the temperature what it say, doubles the bulk and elastic power of steam, (but had
dregs pass off at the other end in a continual stream. And in which, principles are adopted to suppress the watery vapour until the spiritous vapour may rise with a very rapid process, to obtain purer spirits at the first distillation.
The principles of this invention may be conceived, when we consider the common process of distillation, which I suppose to be as follows, viz. The pressure of the atmosphere which is equal to l5lbs. to every square inch surface of the beer in the still, suppresses the watery vapour until the beer is heated to 212 degrees of Fahrenheit's thermometer, or boiling heat; but the spirits being more volatile, its vapour is about double as powerful, and will rise under that pressure at 170 degrees of heat, 42 degrees below the boiling point of water: now, while the heat is kept between those two points, purer spirits are obtained; but the process is too slow, and the distiller to increase it, makes his still boil, which raises large quantities of watery with the spiritous vapour. Now it appears evident, that if we sue the path pointed out by nature, we may, by increasing the pressure, suppress the watery vapour until the spirits rise rapidly, and use less fuel; but this is much more difficult to explain. Any further explanation required, I am willing to give.
OLIVER EVANS.
The foregoing letter was sent by Dr. Mitchill, a senator from the state of New-York, to his friend Dr. Miller, one of the editors of a periodical work, entitled the Medical Repository, to be published therein. John Stevens, Esq. of Hoboken, (New-Jersey) having seen and read it, thought proper to make the following remarks, which were published in the same number of the Repository with the letter.
1st. The inexhaustible steam engine, so called, because it is arranged on such principles that the water in the boiler will not be exhausted by boiling and working the engine; by which means I evade the accumulation of sediment from the water, as it forms a non-conductor of heat on the bottom of the boiler, which will cause it to last 10 times as long. I also evade the accumulation of air to interrupt the vacuum, by which means the vacuum will become more perfect, and the engine have more power, and require less fuel. The principles on which this is done may be easily conceived, if we suppose a still with its condenser so elevated that the worm, after it leaves the condenser, may be turned to lead the spirits back into the still; this still may in theory be boiled for ever, without being exhausted. Thus, after the steam has passed through my engine, it is condensed into water, and returns into the boiler again, and no sediment or air can accumulate from water distilled many times over.
2(1. The volcanic steam engine, in which I attempt to use the principles of the natural volcano, where the furnace and boiler are in one, and where the fire burns without the aid of the atmospheric air to kindle it; but until I shall discover a fuel which will so burn, I use a forcing air pump to kindle the fire. In this engine the boiler and furnace are united, the water round the fire and the flue of the furnace is made to discharge immediately into the water at the bottom of the boiler, and bubble up through it, communicating all the heat of the fire to the water to generate steam; and all the elastic fluid generated by the combustion of the fuel, which I must suppose will be expanded to at least 2000 times the bulk of the fuel, unites with the steam to work the engine, by which means not more than one-fourth part of the fuel will be required, which fits this engine for boats or carriages better than the other.
3d. The perpetual still, arranged upon such principles, that the beer is received at one end, to pass slowly on to the other(r; during which time the sprit is extracted ,and the
projected improvements, and I shall not only listen to you, but thank you into the bargain. Believe me to be, dear sir, with great esteem and regard, yours, &c.
JOHN STEVENS.
A description of his still follows, explained by a drawing, which I cannot
give for want of the plate.
NEW-YORK, JANUARY 12th, 1805.
DEAR SIR,
I AM this moment favoured, by Dr. Miller, with Mr. Evans's project for the improvement of steam engines. He begins with a short history of this noble machine, but has (I will not say through design) omitted mentioning the first attempts made by Captain Savary, in which this very principle of working a steam engine, with steam at a high temperature, and with great elasticity, was resorted to, but without success, although he used boilers, strengthened with radiating bars and bolts within, and strongly hooped without. Here, then, we find the Principe of using strong steam, at a high temperature, is actually as old as the invention of the steam engine itself. Mr. Evans, then, can surely have no well-grounded pretensions to a claim of invention with respect to this principle. That the elasticity of steam is increased by an increment of temperature, is surely no novel discovery. But that this increment should bear a very small proportion to the quantity of heat required for the conversion of water into steam, was a natural and obvious deduction from the important discoveries of Dr. Black respecting latent heat. These discoveries you have yourself, no doubt, heard the doctor detail in his lectures some twenty years ago; and Mr. Belancour's experiments, instituted for the express purpose of ascertaining the ratio of increment of the elasticity of steam, at different temperatures, were made in 1790. Experiments, for the like purpose, were also made by the editors of the Encyclopedia Britannica, and pub15
Remarks on Mr. Evans's project, and an account of other improvements in steam engines, by John Stevens, Esq. of Hoboken: communicated in the following letters to Dr. Mitchill.
NEW-YORK, JANUARY 9th, 1805.
DEAR SIR,
You favour of the 6th instant I have this moment received. Among other projects of Mr. Evans's, I find you enumerate improvements in distillation. Here Mr. Evans and myself are likely to interfere. The idea of distilling with steam is not new. Count Rumford has suggested its practibility in one of his essays. You must observe that Mr. Evans and myself work the steam engine without any condensing apparatus. This steam then, after its discharge from the cylinder, without any diminution of temperature, may be applied to the purpose of distillation. This application of steam naturally suggested itself to me when I first made my experiments on working a steam engine with steam at a high temperature. I have accordingly invented a still adapted to the purpose, simple and cheap in its construction, and calculated to produce spirit of a much better quality than can be obtained in the ordinary way of distilling. A description of my contrivance you will find inclosed; and as it may, in case of interference, prove of use to me, I wish you to preserve this letter and that description, noting thereon the date of its reception.
Of Mr. Evans's volcanic engine, I lately received a description from Dr. Coxe, of Philadelphia, from which, I must confess, I did not form the most exalted opinion of Mr. Evans's project. From the many difficulties that presented themselves, it really appeared to me he was in pursuit of an ignis fi~tziu.v.
You say you started a doubt respecting his supposed improvement in distilling. But although he would not listen to it, the doubt exists as strong as ever." Now, my dear sir, I intreat you to take the same liberty respecting my
years ago, long before I had heard any thing of ~Tr. Evans, it occurred to me that a condenser might be so constructed, as that by exposing a large surface within a small compass, the steam might be so nearly condensed, as to ~ender a jet of cold water unnecessary; but, upon trial, I must candidly confess, it did not answer equal to my expectations. The reason is obvious: the heat could not be conveyed through the metal with sufficient rapidity, so that the temperature within the condenser should be sufficiently low to condense all the steam.
[Here Mr. Stevens has shown that he was not able to comprehend the principles and construction of this engine; he will surely never claim it hereafter: but if he had seen ray specifications and drawings, then the application would have been obvious from the discoveries perhaps, of Newcomen or Watt.
1. " The volcanic steam engine." But till he shall have discovered a fuel which will burn without the aid of atmospheric air, I shall desist from saying any thing about his intended application of this project, to propelling boats and wheel carriages
[He means, I suppose, until he sees it in operation, then the application will be obvious to any one from the burning and explosions of volcanoes.
ad. " The perpetual still" Here, if I understand Mr. Evans, he assumes a very erroneous principle. He concludes that spirits will rise more readily than water, in proportion as the pressure is increased. But the very ingenious experiments of Mr. Dalton have proved incontrovertibly, " that the variation of the force of vapour from all liquids is the same for the same variation of temperature." Thus the force of the vapour of spirit of wine at 175 degrees is equal to 15lbs. and the force of vapour of water at 212 degrees is equal to l5lbs.-increase the temperature of both degrees, and the elastic force of each will be increased equally, viz. to about 261bs. on the square inch. By some experiments
established therein a dozen years ago. The application of this very important law of increment, developed by these gentlemen, to the improvement of the steam engine, was obvious; the great desideratum was to construct a boiler sufficiently strong to withstand a very great pressure of steam.
[Has Doctor Black, Belancour, the editors of the Encyclopedia Britannica, (or even John Stevens, Esq.) ever pointed out the means by which these principles could be advantageously applied to the improvement of steam engines, or did they even suggest such an idea
To apply this wonderful principle," says Mr. Evans,
" I construct my boilers of circular cylindrical forms, of small diameters, the best possible form to contain a great elastic power; and to enlarge their capacity, I extend their length, or increase their number." Here Mr. Evans, for the first time that I have heard of; assumes to himself a principle, for which I have obtained a patent near two years ago For I would ask, whether his boilers before, or even since, have been constructed upon the principle above stated? The boiler he used at the time my patent was obtained, was a metal cylinder of 20 inches diameter, and 20 feet long surrounded by an exterior one of wood. His present boiler is a like cylinder placed in brick work. The only difference between them is, that in the former the fire was made within the cylinder; in the latter it is made to surround i~ He has made no attempt to diminish the diameter of his cylinder, or to increase the number of cylinders. The latter, indeed, he could not do without a manifest interference with my patent. Of this, I doubt not, Mr. Evans himself would be sensible, where he to peruse my specification filed in the patent office.
But, it seems, Mr. Evans has " conceived further, and still greater improvements, which he wishes to put in operation.
1st. " The inexhaustible steam engine." I have nothing to say about this sociable project other than that many
All experimenters agree, that the same law governs both, viz. that within a certain range every addition of about 30 degrees to the temperature, doubles the elasticity. In the above scale, the temperature of the spirits is kept 7 degrees below that of the water. When water is 212, and spirits 205 degrees, the difference is 15lbs. to the inch, and every addition of 30 degrees doubles the power of both, and doubles the difference; three steps brings the difference to 60 lbs. when the spirits will rise with great rapidity, and the watery vapour be totally suppressed. It is wondrous that this was not obvious to Mr. Stevens, from the discoveries of Belancour and Dalton, that he might have claimed "the application of it on certain principles, to the improvement of his notable still."]
While on the subject of distillation-Can you not suggest to me some varnish or cement, that will resist the action of alcohol, which I may substitute in the place of metal for lining my wooden alembics? But spirits are preserved for any length of time in wooden vessels. ~ Would wood be affected by spirits at a temperature of 100 to 150 degrees? I am inclined to think that at the low temperature of the wash in my still, it may not be necessary to defend the wood from the action of the spirit. I shall at least make a trial.
Mr. Evans, proceeding on the calculations given in the Encyclopedia and by Count Rumford, has been led into an error as well as myself, in estimating the increments of the force of steam with given increments of temperature. It is laid down by these authors, that for every increase of 30 degrees of temperature the elasticity of steam is doubled. But Mr. Dalton has proved that the ratio is not equable and constant, but is a gradually diminishing one.
| Temperature | Force of Vapour | Temperature | Force of vapour |
| 9.46 | 160 | 19.00 | 340 |
| `190 | 34.99 | 370 | |
| 220 | 58.21 | 400 | |
| 250 | 88.75 | 430 |
But Mr. Dalton has proved, from a series of very accurate experiments on the elasticity or force of sulphuric ether, at different temperatures, from 32 to 212 degrees, that the increments of force are in a direct ratio to the increments of force of watery vapour from 142 to 322 degrees. The boiling point of ether in the open air being 102, that of water 212 degrees.
It is presumable, therefore, that spirit vapour is governed by the same law of increment, and that Mr. Achard committed some error.
[Had I permitted Mr. Stevens to have palmed such an error or misrepresentation on the public, to remain as an impediment to improvements, and especially to my proposed improvement on distillation, I would have been guilty of a neglect of duty. He says that the force of vapour at 175 degrees is equal to 15lbs. then he should have stated it thus:
| Temp of watery vapour | Temp of spiritous vapour | In mer | Elasticity or force of both |
| 209 | 1730 | 28.1 | 36 |
| 189 | 154.6 | 18.5 | 34.4 |
| 168 | 134.4 | 11.05 | 33.6 |
experience, in this bewitching department of experiments and inventions, ought to have taught me long ago, the truth and accuracy of Mr. Evans's calculation. Mr. Evans laments that he has already risqued 2000 dollars. Alas! I have risqued more than ten times that amount, and although I have been more than twenty years hard at work, I have as yet derived not one shilling advantage from all my various schemes and projects. If, therefore, now that I think I see some prospect of indemnification, I should discover some degree of solicitude to secure the property of an invention, no one, I 'trust, will blame me.
It may not be amiss to mention, that steam discharged from the cylinder, may be applied to working one of Watt and Bolton's engines; and I think it probable that it would not require more fuel than if worked in the common way. In this case, the whole of the work performed by my engine would be saved.
[I recollect perfectly well having explained this to Dr. Coxe, as I did to others, saying, that all the power which I yet had, was so much over and above the power of Bolton and Watt's engine, that the steam after it left my engine would work one of theirs; and that I could add their power to my engine, by the use of a condenser. Mr. Stevens has not conceived this simple mode, but took up the idea of an additional engine. Indeed, Mr. Stevens, this circumstance added to all the rest, gives the whole a dark appearance; and your endeavours to impress the public mind with an unfavourable opinion of my improvements, and that I have assumed to myself some of your inventions, is both illiberal and injurious to a great degree.]
Mr. Evans tells us, " that the great power and simple structure of his engine, fits it for propelling boats up the Mississippi, and carriages on turnpike roads; two of the. most difficult applications." Difficult indeed it must prove, should he attempt to effect either of these purposes with his unwieldy boiler of 20 feet in length and 3 or 4 feet dimater equal to l3Olbs. on the square inch. This we find is very far short of Mr. Evans's extravagant calculation, that 424 degrees gives steam 128 times as strong as steam at the temperature of 212 degrees. From my experiments detailed hereafter, it will appear that this calculation of Mr. Dalton's is too low; that 424 degrees would give steam equal to 450 in.
[Continue this scale of the diminution of the ratio, and the increase of elasticity by the addition of heat will entirely cease before the elasticity would be sufficient to burst one of my boilers; so that Mr. Stevens removes all danger on that score: but I fear that neither Dalton nor him are right. They have, however, left me a good power; 1301bs. to the inch is quite sufficient.]
Mr. Evans exaggerates enormously the strength of his boiler, when he estimates it capable of sustaining a pressure of 15001bs. on each square inch. Count Rumford has ascertained, by actual experiment, that a bar of wrought iron, an inch square, will require about 63,OOOlbs. to fracture it. Mr. Evans's boiler is composed of wrought iron a quarter of an inch thick, and as it is 20 inches diameter, or about 60 inches in circumference, 60 multiplied by 1500 is equal to 90,OOOlbs. pressure on each inch of the circumference of his boiler. To withstand this pressure, it ought to be an inch and a half thick instead of a quarter. Contrast this with the tubes of which my boiler is composed of an inch diameter, giving about 3 inches in circumference, 3 multiplied by 1500 is equal to 45001bs. which would require a thickness of only one-fourteenth of an inch of wrought iron.
[Here Mr. Stevens has magnified, by his calculations, 15001bs. to the inch circumference of my boiler to 90,OOOlbs. and then proceeds on his error to find the thickness of iron necessary to bear it. I advise him to read the rules, with their demonstrations, which I have laid down.]
Mr. Evans considers his inventions, although of the utmost importance, as a bad speculation. in my own sad experiments
_
constructed a rotary engine, on the axis of which revolved a wheel at the stern of the boat like a wind-mill or smoke-jack. It was impossible to make a more simple application of the power. After repeated trials, however, I found it Impracticable to preserve a sufficient degree of tightness in the packing, &c. The yellow fever came on and interrupted my further progress The next winter I was employed in constructing another rotary engine on a new plan; but this, on trial, proved no better than the first. Thus I lost a whole year, and was compelled, reluctantly, to have recourse to Watt and Bolton's engine. I set immediately to work, and some time in May last had my machinery all on board a boat. My cylinder is 4~ inches in the bore, with a 9 inch stroke. The complex machinery for opening and shutting the valves of Watt and Bolton's engine I have reduced to a single movement. The lever beam I have dispensed with altogether, as also with the condensing apparatus and air-pump.
[Here Mr. Stevens expressly states, that he lost a whole year after he had obtained his patent, in pursuit of projects which proved futile, and that he was compelled, reluctantly, to have recourse to Watt and Bolton's engine. Why did he not speak truly, and say Evans's engine .~ for it is not Watt and Bolton that he follows, but he treads in my steps exactly. I had in use during two years before that time all the improvements he had recourse to. The heavy lever beam I had dispensed with altogether, as well as the condenser and air-pump, and used a small forcing pump to supply my boiler. The principle of the great elastic power of steam, discovered by the Marquis of Worcester, (but which had been abandoned for one hundred years, as unmanageable) I had applied to propel a piston in a cylinder similar in its construction and operation to Watt and Bolton's; producing an engine ten times as powerful, expending only one-third the fuel to (10 equal work, and costing only half the price, compared to Watt and Bolton's. Mr. Stevens has been reluctantly compelled to follow me, by adopting all my improvements.]
. It is plain to be seen, that, to perform these very arduous exploits, Mr. Evans does not mean to employ his own boilers, but to avail himself of the principle he has so dexterously assumed to himself, viz. to increase the number of his cylinders. To place this matter in a striking point of view, I will give yon the dimensions of a boiler I pro-pose putting on board of a vessel to ply as a passage boat betwixt this place and Albany. Length of the boiler, 6 feet3 breadth, 4 feet; depth, 2 feet. A boiler of these dimensions will expose, in the most advantageous manner, upwards of 400 feet of surface to the action of the fire. To expose an equal surface with a boiler on Mr. Evans's plan, would require it to be upwards of 80 feet long; but were it twice that length, it would not give an equal quantity of steam, as it would be impracticable to apply heat to it advantageously.
Pardon the great length to which this letter is protracted:
the objects I conceive myself on the point of accomplishing are of immense importance. You have sent forward Mr. Evans's paper to be inserted in the Medical Repository. This has a wide circulation, not only in the United States, but throughout all Europe. I therefore think, that in justice to myself and the world, I should have an opportunity of asserting and maintaining what I conceive to be my right. I should wish, therefore that you would forward this and my former letter, with a certified copy of my specification, filed in the patent office, without delay, so that 1 may be able to insert extracts therefrom, in the same number of the Medical Repository with Mr. Evans's paper. I am, my dear sir, with the sincerest regard, yours, &c.
JOHN STEVENS.
It may not be amiss to go into a short detail of the progress I have made since obtaining the patent. My object was, in the first instance, to construct an engine, adapted more immediately to the purpose of propelling a boat. This was an error which occasioned the loss of the first season.
My boiler was on a similar construction with the ono described in my
specification. It was 2 feet long, 15 inches wide, and 10 or 12 inches high,
and consisted of 81 tubes, 2 feet long, and 1 inch diameter. As my boat
was nearly 25 feet long, and 5 feet wide, I was not able, with safety, to
raise a chimney of more than 3 or 4 feet high. The consequence was, I was
unable to establish a sufficient draft between the interstices of the tubes,
so as to support a brisk fire; and the power of the engine was, of course,
too feeble to give much motion to the boat. I then altered the furnace ~o
as to allow room between the tubes and the brick work for a draft. This
was applying the heat of the fire to a great disadvantage; but I could do
no better. Under these unfavourable circumstances, however, I made another
trial, and gave to the boat a velocity of about four miles an hour. After
having made repeated trials with her, my son undertook to cross over from
Hoboken to New-York, when, unfortunately, as she had nearly reached the
wharf, the steam pipe gave way, having been put together with soft solder.
This threw the crew into some confusion, and by dashing a pail of water
suddenly on the boiler, the immediate contraction of the metal cracked a
number of the tubes, and thus put an end to all further experiments with
this boiler. To avoid a similar accident, I set about constructing a boiler
on another plan. A single plate of brass was placed horizontally, and tubes
were screwed into the under side in a vertical direction. It was rate in
the fall before we could bring our engine into operation again; but for
want of sufficient draft, its performance was not much more powerful than
before. It was kept going, occasionally, for a fortnight or three weeks,
the boat making excursions of two or three miles up and down the river;
and, finally, on the approach of winter, the machinery was taken out of
the boat. I will must mention, that in the spring, previously to putting
it aboard the boat, the engine was set agoing in the shop. At first, a stove
pipe was carried out of one of the windows; but with all our endeavours,
though the boiler was perfectly
right, we could not raise the safety valve loaded with about 50lbs. to the square inch. The flue was then carried out above the roof, and in a few minutes a few shavings would set the engine agoing. As I was impatient to try its performance in the boat, I did not apply it to any sort of work, so that I made no estimate of its power to ascertain how much work it would perform with a given quantity of fuel. When on board the boat we repeatedly stopped the engine till the steam would raise the safety valve; when, for a short distance, the boat would go at the rate of not less than seven or eight miles an hour.
I am at present employed in constructing a boiler on a different plan from the last, and which, I expect, will turn out a great improvement on it. And as it will be much larger, and placed in a building with a lofty chimney, I expect to be able to work with a load on the safety valve of l00lbs. or perhaps 2001bs. to the square inch. And as I purpose. pose putting up a pair of mill-stones, I shall also be able to determine the quantity of work performed with a given quantity of fuel.*
Should this, on trial, as I feel fully confident it will, answer my expectations, I shall immediately set about one on a still larger scale, to be placed on board a vessel to ply as a passage boat between this city and Albany.
[Mr. Stevens states that his next boiler will be much larger. His inch
tubes will, no doubt, swell to cylinders of
That the Saving of fuel must be very great indeed there cannot be a doubt 0. Evans States that with a 102(1 of 281bs. to the square inch, three times the work is performed with an equal quantity of fuel. What then 'nay we expect when the elasticity of the Steam equals lOOlbs. or perhaps 2OOlbs. on the square inch. The experiments of Dr. Black and others prove, that when water is converted into Steam, 600 or 900 deg. of heat are absorbed. Now, an addition of less than 400 deg. would bring this steam to the heat of boiling oil, its elasticity would then (according to my experiments) be equal to 40 atmospheres, or 60Olbs. on the square inch. Thus then, if 900 degrees equal one atmosphere, 1300 degrees equal 40 atmospheres; but to raise the temperature of steam in the above proportion Cannot require any thing like 40 times the fuel.
The area of a circle of three-eighths of an inch diameter is very nearly one-ninth of a square inch. Thus then, 12+ lbs. the average of weights raised by the explosions, multiplied by 9, gives 650lbs on the square inch for the elasticity of the steam at rise temperature of boiling oil, which is usually estimated at 600 degrees of Fahrenheit's thermometer. This is an elasticity considerably greater than the result which Mr. Dalton's principles of calculation would afford, but much less than the calculations of Mr. Achard and the editors of the Encyclopedia Britannica would make
it. By the experiments of these gentlemen, it appears that from 150 to 280 degrees (which was as far as their experiments extended) an addition of one inch of mercury for every 10 degrees was very nearly the ratio of increment, if we except the last 10 degrees, which is evidently erroneous. Now, it is not a little remarkable, that the same ratio of increment, extended to 600 degrees, gives an elasticity coinciding very nearly with the result of my experiment. Thus,
| 350 | 252 |
| 400 | 382 |
| 450 | 537 |
| 500 | 717 |
| 550 | 922 |
| 600 | |
| 1152 equal to 767 lbs | |
[Flaxseed oil contains a portion of water, and will boil at a lower temperature than 600 degrees: this may have led Mr. Stevens into an error; but whether the result which he has drawn be true or not, experience shows that we can obtain any power that we would attempt to hold in our boilers, and sufficient for any purpose. In the year 18011 constructed, for the purpose of making experiments, a small boiler of cedar wood, 12 inches diameter and 20 inches in height, strongly hooped with iron: inside of this cylinder was put a cast iron furnace 7 inches diameter at the lower and 3
20, then to 30 inches diameter, just as large as will be quite safe to hold the power. Then he may feel fully confident that it will answer his expectations, and that he may work with a load on his safety valve of 100 or perhaps 200ibs. to the inch, as well as Evans. Dr. Coxe saw him have the whole in actual operation, and it has performed well two years already. Mr. Stevens, in his note, shows that he misunderstood me respecting the load on the safety valve, viz. 281bs. lessening the fuel to one-third. He has here spoken leatnedly on the principles which I had explained long before to Dr. Coxe.]
I have lately been engaged in making a number of experiments, to ascertain the elasticity of steam at the temperature of boiling oil. In making similar experiments about two years ago, I employed a lever to keep down the valve, with a weight suspended thereon like a steelyard. This mode of operating was necessarily inaccurate. I now pursued a plan which was not liable to the same errors. A brass tube about ten inches long, and about one inch diameter, was first fixed in a perpendicular direction in an iron vessel containing common paint oil; on the top of this tube, the surface of which was perfectly flat, a valve was accurately fitted; the bore of the tube is precisely three-eighths of an inch in diameter; a tea-spoonful of water was then poured into the tube (which filled it about one-fourth full), the valve raced thereon, and loaded with 73 lbs. After the oil had been made to boil some time, about three fourths of a pound was gradually removed. To do this readily I made use of nails. An explosion then took place, but without much noise, as the steam was but barely able to make its escape.
This experiment was tried repeatedly with little variation; so that the elasticity of steam, at the temperature of boiling oil, may be depended on, as being ascertained with a considerable degree of accuracy. I am certain it cannot deviate from truth, more than one part in a hundred.
than 280 degrees, at which temperature the elasticity of steam was found equal to about four times the pressure of the atmosphere. By experiments which have lately been made by myself, the elasticity of steam at the temperature of boiling oil, which has been estimated at 600 degrees was found equal to upwards of 40 times the pressure of the atmosphere.
To the discovery of this principle or law, which obtains when water assumes
a state of vapour, I certainly can lay no claim but to the application of
it, upon certain principles, to the improvement of the steam engine, I do
claim exclusive right. It is obvious that, to derive advantages from an
application of this principle, it is absolutely necessary that the vessel
or vessels used for generating steam should have strength sufficient to
withstand the great pressure arising from an increase of elasticity in the
steam. But this pressure is increased or diminished in proportion to the
capacity of the containing vessel. The principle then, to which I claim
exclusive right, consists in forming a boiler by means of a system, or combination
of a number of small! vessels, instead of using, as in the usual mode, one
large one; the relative strength of the materials of which these vessels
are composed increasing in proportion to the diminution of capacity. It
will readily occur that there are an infinite variety of possible modes
of effecting such combinations; but, from the nature of the case, there
are certain limits, beyond which it becomes impracticable to carry our improvements.
In the boiler I am about to describe, I flatter myself the improvement is
carried nearly to the utmost extent the principle is capable of.
SPECIFICATIONS
Suppose a plate of brass, of one foot square, perforated by a number of copper tubes of an inch diameter and two feet long, the other ends of which to be inserted in like manner, into a similar plate of brass: the tubes, to insure
inches diameter at the upper end, with a flange 12 inches diameter at
each end, which served as heads for the wooden cylinder: I fixed a safety
valve and cock in the upper end. The space between the furnace and wooden
cylinder contained the water which surrounded the fire. A small fire in
this furnace soon raised the power of the steam to such a degree as to lift
the safety valve loaded with 1521bs. to the inch. I then opened the cock,
regulating it so as to keep the valve just lifting. The quantity of steam
which continued to escape while the fire was kept up, and the force with
which it issued, was astonishing. The degree of heat which produced this
immense power did not in the least injure the cedar wood. No further experiments
were necessary to prove the practicability of the application of my principles.]
copy OF MR. STEVENS'S PATENT AND SPECIFICATION.
To all to whom these presents shall come, greeting:
I certify that the annexed writing is a true copy of the specification of a patent granted to John Stevens, duly compared with the original on file in this office.
In faith hereof, I, James Madison, Secretary for the department of State of the United States of America, have
signed these presents, and caused the seal of my (L. S.) office to be affixed hereto, at the city of Washing.
ton, this sixteenth day of January, A. D. 1805, and in the twenty-ninth year of the independence of the said States.
JAMES MADISON.
From a series of experiments made in France, in 1790, by Mr. Belancour, under the auspices of the Royal Academy of Sciences, it has been found that, within a certain range, the elasticity of steam is nearly doubled by every addition of temperature equal to thirty degrees of Fahrenheit's thermometer. These experiments were carried no higher
one year before he took out his patent, far exceeding every application
of steam before known or used.And Mr. Stevens, well knowing
that I claimed the exclusive right to the Invention, attempted to secure
to himself the exclusive right of using this my discovery, which had cost
me 2000 dollars in cash to put in useful operation, besides my time which
I cannot rate at less than another thousand dollars. But he says he has
been twenty years hard at work, spent 20,000 dollars, and succeeded in nothing;
therefore he thinks that he is entitled to his claim. The date of his patent
(April 11th, 1803) is two months after Dr. Coxe had called on me. He has
specified nothing but what was in use before; and all his projects, that
he has yet mentioned, on which he has spent his labour and money1 have been
tried by others long ago.]
OLIVER EVANS'S REPLY.
extracted from the Medical Repository.
PHILADELPHIA, APRIL 13, 1805. SIR,
AT the several times which Dr. Coxe called on me at your request, to obtain information respecting the construction and principles of my improvements on steam engines, I asked him what was the object of your numerous and pointed questions. Does he intend any interference with my invention? He answered, that you were a gentleman, and was making experiments for your amusement that therefore I need not apprehend any interference. Having received this assurance, I communicated freely, answering all your questions, and explained the principles without reserve, as I have done for twenty-one years past (ever since I first conceived the principles) to every gentlemen whom I conversed with on the subject; and when I was informed by Dr. Mitchill, in December or January last, that you intended to comment on the paper which I had laid before each member of congress individually, to show the the differ-
17
their tightness, to be cast in the plates. These plate are to be closed at each end of the pipes by a strong cap of cast iron or brass, so as to leave a space of an inch or two between the plates and their respective caps. Screw bolts pass through the caps into the plates. The necessary supply of water is to be injected by means of a forcing pump into the cap at one end, and through a tube inserted into the cap at the other end the steam is to be conveyed to the cylinder of a steam engine. As the boiler now described embraces the most eligible mode that has yet occurred to me of applying the principle, it is unnecessary to give descriptions of boilers less perfect in form and construction, especially as these forms may be diversified in a thousand different modes.
(Signed) JOHN STEVENS.
signed in presence of as,
JOHN KEESE,
CHARLEs T. KEESE.
The patent is dated April the 11 th 1803.
[Mr. Stevens in his specification, confines his invention to his boiler, which was patented by Mr. James Runisey, August 6th, 1791. Mr. Runisey's words in his specification are as follows: " That is new modes of generating steam in greater quantities, to a greater degree of expansion, and with much less expense of fuel, than by any mode ever before known, by means of a boiler consisting of, or formed by, homogeneous incurvated tubes, connected together and composed of metal least subject to corrode." But Mr. Runisey failed in the application of the principle, therefore, if Mr. Stevens has made any improvement which will cause it to answer the purpose, he is intitled to a patent. These are the principles on which he claims the exclusive right of using strong elastic steam, which was not known to be useful, nor used to any working engine, until I discovered the means of application, and had it in actual operation
Now, sir, what benefits do you expect to arise from your having laid me under the necessity not only of defending my character, but my interest? Shall we criminate and recriminate each other in public, until we give good people cause to pronounce us fools? I wish to employ my time to a more useful purpose. To be sure, you have greatly lessened the force of your remarks, by informing us that you have been hard at work for twenty years, and expended 20,000 dollars, and have not yet derived one shilling from all your various schemes and projects. Surely, sir, this experience of your's was sufficient to have taught you, that you are not qualified to pass judgment on the works of those who have been successful. It is at least sufficient to convince other people. Can you point out one single instance wherein the man whose work you condemn has failed of success in bringing into operation and use any thing he once attempted?
In answer to your charge I might retort on you as follows:
1. You say I am in pursuit of an ignis fatuus; but experience has taught me, that many who think themselves wise have said, and will say the same thing, until they either understand the principles, or see them in operation.
2. I was not publishing, but only writing to each individual member of congress, therefore there was no need of mentioning Captain Savary's application of strong elastic steam in his first attempts; but you have omitted to mention (I will not say through design) that he soon gave it up for want of a true knowledge of the principles which only could direct to a useful application. I was showing the difference of the principles and powers between Watt and Bolton's steam engine (which has long been esteemed the best) and my own, to show how far my principles exceed their's, as justly to entitle me not only to an exclusive right for using them, &c. but to the fostering aid of congress, so far as to protect me in the exclusive enjoyment of my ]mprovements on mills for another term that I might apear
the presensce in principle of the best English steam engines and my own, (which I did not write for publication, nor did I publish it) he then told me that you would treat the subject like a gentleman; therefore I rested so perfectly easy that I did not peruse your comment until yesterday, three months after its date. I assure you I was not a little surprised and disappointed to find, that as far as your credit and influence may extend as a scientific character, your comment tends to stigmatize me, to impede the introduction of my improvements, by increasing the doubts in the minds of the people about the principles of my engine, which has been in actual practice and highly useful operation for three years, far exceeding all others of which I have any knowledge. Although the working cylinder is only 6 inches in diameter and length of stroke 18 inches, she will grind 400 bushels of plaster in twenty-four hours, or saw 200 feet of marble stone; and when my principles are fairly and fully put in operation, the work will be doubled, or perhaps trebled.
1. You say I am in pursuit of an ignis fatuus.
2. You indirectly insinuate that I, through design, omit to mention that Captain Savary wrought his engine with strong elastic steam.
3. That I have dexterously assumed to myself a principle for which you obtained a patent two years ago.
4. You attempt to turn my ideas and my further proposed improvements into ridicule.
5. You say I have assumed very erroneous principles in my improvements of my steam engines, as well as my perpetual still.
6. You say that I have exaggerated enormously the strength of my boiler, and endeavour to show that it is incompetent to the task I assign to it.
7. You say that the application of the discoveries made by Dr. Black, twenty years ago, respecting latent heat, and the very important law of increment, developed by certain gentlemen, to the improvement of steam engines, was obvious; therefore I can have no well grounded claim.
ply the net proceeds to defray the expenses of extending the use and introduction of my improved steam engine, as well as of the expensive experiments, which will be necessary to put in practice my further proposed improvements, which I have specified, and I do assure you, sir, you do not show you understand them.
3. Have I been half so dexterous as yourself; who sent Dr. Coxe to view my principles, then in operation and use one year, (publicly exhibited and explained to every one who inquired after the principles) and to put a number of questions to me, which drew in answer, a full explanation of the construction and principles of my invention, and 'which, when you were in possession of; the improvement became obvious to you, and you went and attempted to take out a patent for, and assumed it to yourself; but herein you have failed for want of a competent knowledge; besides you are not the original inventor.
4. Do you really believe that the fire of volcanoes is kindled by atmospheric air? If you do, please to point Out to us the apertures by which it is possible for the air to enter against a force which casts up rocks two thousand feet high; or else show why fuel, which burns in one place without the aid of atmospheric air to kindle it, will not so burn in another place with the aid it has, be that what it may; or why air cannot be substituted instead of that unknown aid in the manner which I have proposed.
5. Are you sure you are competent to assert, that I have assumed very erroneous principles, while you show you do not understand them yourself? or that Mr. Dalton's experiments are more accurate, or the result he has drawn nearer the truth than those of the editors of the Encyclopedia? That Dalton, as well as yourself, is wrong, is evident, because, if we continue his scale of diminution of the ratio, the increase of elasticity by the increase of heat will entirely encase long before the power be sufficiently augmented to burst the cannon, as stated by the earl of Worcester.
125
6. Have you any rule for ascertaining the power exerted to burst a boiler, by which you can tell how enormously I have exaggerated the strength of my boiler? The rule by which you seem to have calculated is really false, and your calculations are a specimen of your qualifications, as there is, unfortunately for you, no solution of this useful problem to be found in any book that I can find; you must, therefore, have recourse to your own inventive genius, and it was absolutely necessary you should possess this knowledge to enable you to arrange a steam engine.
7. Was it not equally obvious, that a pipe of 1 inch diameter, would expose more surface to the heat of the fire, and bear a greater elastic power of steam, in proportion to its contents, than one of 20 inches diameter. But who ever made a boiler consisting of pipes of 1 inch only in diameter, to work a steam engine, until it was done by John Stevens, Esq. of Hoboken; excepting only the late ingenious colonel James Rumse,-, about fourteen years ago in the city of Philadelphia, and afterwards in the city of London. His patent is dated August the 6th, 1791, which will expire the 6th day of August next; he, however, as I have been informed, found it would not do in practice, and therefore gave it up as an ignis fatuns. But shall this discovery, or patent of his, make your claim groundless, or prevent you from pursuing the same ignis fatuus, for which you took out a patent two years ago? I hope not, or else there could be but few well grounded claims.
Your ignorance of the principles of my invention has caused you thus far to commit and set yourself in the way as an obstacle to the introduction of the most useful improvements ever made on steam engines: but you have one consolation; this will serve more to perpetuate on memory than your twenty years hard work, and 20,000 dollars risked.
You may rest perfectly easy in the possession of your boiler, as you have specified it; and of your scheme of'
experiments, would accomplish the great ends of propelling boats and land carriages. We need not contend, the range is sufficient for us both; let us unite our resources. If I had possessed the sum to expend twenty years ago that you say you have already expended, I do believe that my inventions and improvements might, at this day, have been doing the labour of at least 100,000 men in this country.
When the blind man took the lame one on his back, they both travelled safely; but I am as doubtful of the success of your project of a boiler as you are of my volcanic one; and think I could convince you of the great probability of the success of my plan of pouring all die heat of the fire into the water, instead of passing up the chimney, which is all that can be possibly got from the fuel, and would be lighter, and far more durable and easier repaired than your's; but I will not risk the expense of the experiments until there be a better prospect of reward. I have made a small boiler on that principle, which appeared to answer well; all the heat of the fire entered the water to generate steam, which, united with the elastic fluid, generated by the consumption of fuel, formed the agent to work the engine.
MR. STEVENS'S REPLY.
Extracted from the Medical Repository.
THE only part of the above letter, which I consider sufficiently important to require any notice on my part, is the charge Mr. Evans has thought proper to bring forward against me, of sending Dr. Coxe to him to steal his invention; for which he is pleased to say, " I have taken out a patent, and assumed it to myself." To repel so odious a charge, it will be necessary to go into a detail much longer than I could wish.
Mr. Evans, in the above letter, admits unequivocally, that he has no claim whatever to the boiler specified in
working one of Watt and Bolton's by the steam of one of my engines after it leaves it ; for I can produce more effect from the steam by one cylinder than I can by using two, as you propose: and of your mode of distilling by steam, as described in your comment, I would wish to know when you invented it. But if you will attempt to infringe my patent, the best way will be to decide the matter in a court of law, without troubling the public therewith. I am sorry to be obliged to spend my time thus, as I am engaged in writing for the press, a small treatise on the principles and powers of steam, and of my own improvements, which, when published, many things will become obvious to you that are not so now but then you can easily show that they were so for twenty years past, because my deductions are all drawn from the experiments, discoveries, reasoning, &c. of Dr. Black, and other philosophers, who have lived ~ wrote before me.
I might, in the same time thus spent, have discovered or wrote something useful.
To conclude, seeing you have so dexterously procured your injurious remarks a place in the Medical Repository, I will thank you to obtain a place in the same work for this letter, or adopt any means you please to place me on as good grounds as you found me, and you will much oblige,
Sir, your humble servant,
OLIVER EVANS.
JOHN STEVENS, Esq. of Hoboken,
near New-York.
p 5 After the publication of the above, and you quit all claims to my inventions, I shall consider myself redressed, and shall be willing to correspond with you on friendly terms. We should assist, instead of injuring each other.
If your plan of a boiler should prove useful in practice, and generate more steam, with equal fuel, than mine, I shall rejoice at the improvement, which, united with my improve-
strength of one atmosphere to two than was necessary at first to raise it to one ; or, in other words, if we add to steam as much more heat as it may already contain, we shall make it more than twice as elastic."
Here, then, we find that the advantages of using strong steam were suggested and pointed out by me before I heard, or, indeed, could have heard of Mr. Belancour's experiments.* But after it had been satisfactorily proved by these experiments, that the increase of the elasticity of steam was in a far greater ratio than the increase of heat, it could not be imagined that I should have remained insensible of the immense importance of the application of this principle to the improvement of the steam engine. The truth is, that ever since the period above mentioned, I have been more or less engaged in various projects for applying this principle to advantage. To enumerate and describe the boilers I have constructed on different plans, with a view to effect this object in the most convenient and eligible mode, would be tedious and unnecessary, more especially as Mr. Evans does not seem disposed to dispute the right of invention of any specific improvements of the steam engine; but generally the exclusive right of applying to this purpose the above mentioned principle.
[His words, on November 23, 1790, show the extent of his knowledge
of the principles at that time to have been mere conjecture and supposition:
for if Mr. Blakey had succeeded in his attempt to apply the principle, by
the intervention of oil, in the year 1700; or if Captain Savary or the Marquis
of Worcester had applied their strong elastic steam to move a piston in
a cylinder; or if Mr. Newcomen had applied Savary's boiler to generate strong
elastic steam, to propel his piston, the work would have been done, and
These experiments were made in Paris, in 1790, and were never heard of by me until they appeared in the new edition of the encyclopedia Britannica.
my patent. What, then, is it I have stolen from him ~ He affects, it seems, to take it for granted, that the idea of using steam at a high temperature and great elasticity, never occurred to me before I had obtained information on that head from Dr. Coxe. But the following extract from a statement,* presented in Feb. 1791, to the Board of Commissioners appointed to adjust and settle interfering claims for exclusive patent rights, will prove, in the most satisfactory manner, that the idea of the great advantages resulting from using steam of high temperature and great elasticity, had actually occurred to me many years ago: and, I should suppose, even before Mr. Evans had thought of it himself. In describing what I then thought an improvement of the steam engine, which, at this time, it is unnecessary to explain, I make use of the following words:
For if; by the intervention of water or oil, we should be enabled to make use of steam of four times, for instance, of the usual strength, the advantages we should derive from it would be very great.
1. A cylinder of 2 feet diameter would be as powerful as one of 4 feet diameter.
2. There are sufficient grounds to induce us to believe, at least, that
less heat is required to raise steam from the
This statement was drawn up in conformity to the following notification:
Philadelphia, November 2j~, 1790.
Some of the claims for patents, founded on the supposed discovery of new applications of steam to useful purposes, not having been stated precisely as to be satisfactory to the board, and it being their wish to hear all those claims together,
Ordered, That the first Monday of February next be appointed for tile hearing of all parties interested; that notice be given to John Fitch, James Rumsey, Nathan Read, Isaac Biggs, and John Stevens, of this order; and that each of them be required to transmit in writing to the Board, a precise statement of their several inventions, and of the content thereof.
extract from the Miniltes,
HENRY REMSEN, Jun..
might have saved Mr. Stevens 20,000 dollars, besides much study and labour: but it is left for us to contend about. Admitting all Mr. Stevens's statements are true, then the facts appear to be as follows, viz. In the year 1784, 1 conceived the means of applying the principle, and in 1786 I explained it to the legislature of Pennsylvania, but they refused to grant me the patent. Early in 1787, I explained it to the legislature of Maryland, and obtained the exclusive right of using it for fourteen years, but did not commence the execution for seventeen years after my first discovery of the means of applying the principle, not being able to find any one willing to join me in risking the expense. Mr. Stevens asserts, that in 1790 he had some distant ideas of the existence of the principle, and that he had been at work which he continued for twenty years, but did not succeed. At the end of seventeen years I went to work, put the principles in operation, and succeeded beyond my expectations. A gentleman having seen the engine at work was astonished at its operation, and undertook to announce the discovery to the public, stating its great performance. This Mr. Stevens gets sight of, sends to Dr. Coxe, contains a full account of the construction of my engine, and explanation of my principles. He then took out a patent, attempting to secure to himself the exclusive right of using the discovery on certain principles; which I never heard of his having done, until I read the specification published by himself, in his unprovoked attack on me. Being ashamed immediately to adopt my engine exactly, he spent one year more (the last of his twenty years) on projects of his own, but could not succeed; and was at last reluctantly compelled to follow me exactly, by adopting every improvement which I had made9 calling it Bolton and Watt's engine. If Mr. Stevens had really understood the principle, he might in the course of his twenty years labour have put it in operation before I began, and then his claim would have been much better supported.]
But were we even to admit that Mr. Evans was really the original discoverer of this all-powerful principle he would, l apprehend, even in this case, find it impracticable to secure against infringement a claim of exclusive right to the application of it. How, I would ask him, could he prevent me or any other man from loading at pleasure the safety valve; a practice coeval with the first invention of the steam engine itself? Captain Savary's engines were capable of raising water from 100 to 200 feet high; consequently he was in the habit of loading his safety valve with 50 to 100 lbs. on the square inch.
In this paragraph Mr. Stevens has discovered his original intention in making the attack, viz. to destroy my exclusive right totally. Mr. Watt met with many such attacks. He could not prevent any person from condensing their steam, a practice coeval with the use of the cylinder and piston; but fortunately for him, as Mr. Stevens did not set as judge, he did prevented others from condensing their steam in his improved way, and confined them to what was before known and used. If Mr. Stevens were to set as judge on my case, I should have little hope; but with any other judge or jury I fear not to risk the matter. Although I do not expect to prevent any one from loading their safety valve, in such engines and for such purposes as were before known or used, yet if they attempt to use great elastic power of steam, die application of which I have discovered, explained and made known at a great expense, I expect to be able to prevent Mr. Stevens himself or any other person from doing so. If not, no patent can be supported; for surely none is better founded. It was be seen that I have made greater improvements on steam engines than any other man; removed the obstacles, and opened a clear and distinct view to still far greater improvements. Compare them with Bolton and Watt's improved Newcomen's engine: They contrived to condense the steam in a vessel separate from the cylinder, and to put steam in above as well as below the
piston, thereby obtaining a double stroke: their plan required the addition of an air-pump, which they applied:
their engine proved more powerful, was easier governed, required only one-fourth the fuel to do die same work, and was pronounced the greatest of human inventions. I have made a total change in the system: I have applied the Marquis of Worcester's discovery, (after its having been abandoned one hundred years) to move a piston in a cylinder; discovered the great advantage of using strong elastic steam, demonstrated, explained and made it known: I have dispensed with the heavy lever beam, condenser and air-pump, and simplified the construction of the boiler, cylinder, piston, and working gears: my plan required a small forcing pump to supply the boiler, which was applied. Thus, I have produced an engine ten times as powerful, more governable, and easier varied to suit any task assigned to it than Bolton and Watt's: it can be constructed at half the price, and will expend only one-third the fuel to do as much work as their's, and is applicable to every purpose to which their's can be applied, besides a great many more. I have specified and explained by drawings, five differently constructed engines all of which will work well to produce immediate circular motion, on my new principle of confining and retaining the steam to increase the heat and elasticity; but these are worth nothing if wrought on the old principle. Indeed, I fear there is nothing left for Mr. Stevens to discover in the art. I hope I am not guilty of egotism in stating facts, when the public good and my own interest require it.]
And now, I hope, I have done with Mr. Evans. Nothing less than the necessity of vindicating myself against the foul aspersion he has thought proper to bring forward against me, could have induced me to have set my pen to paper. I still, however, entertain the most favourable opinion of Mr. Evans's candour and integrity, and am disposed to think, that, when his passion shall have subsided, he will
sincerely regret the gross abuse he has bestowed on me; and probably the time is not far distant, when he will be convinced of the truth and justness of the remarks I have taken the liberty of making on his various projects, and the angry strain of invective which he now indulges himself in, will ultimately give grace to grateful acknowledgments for the services I have rendered him.
The world are greatly indebted to Mr. Evans for his ingenious improvements of mill machinery; and I sincerely hope, that his distinguished mechanical abilities may still continue to be exerted in a way best calculated to promote his own individual interest, and, at the same time, render essential benefits to the community at large.
[Here Mr. Stevens hopes to have done with me; but why did he begin? What prompted him to make such an unprovoked and illiberal attack? Is truth, when stated by me, foul aspersion; and error, when advanced by him, truth and meekness? I did not say he sent Dr. Coxe to steal my invention; this he has discovered himself, and he is certainly best acquainted with his own motives. Of Mr. Stevens's candour I am doubtful, but I hope my suspicions may prove groundless. Why did he not send me a copy of his reply before he published it, as I had done by sending him my letter in answer to his remarks? Had he done this, and not attempted to hold an undue advantage, after being himself the aggressor, he might have been done with me. "I still, however, entertain the most favourable opinion" of Mr. Steven's patriotism: " the world are greatly indebted to him for his" laudable pursuits; and I hope that when I discover the great good he has done me, by " the remarks he has taken the liberty of making on my various projects," that my "angry strain of invective will give place to grate full acknowledgments." I sincerely wish Mr. Stevens success in his laudable undertakings, and that they may prove beneficial "to the community at large."
it to boil and the ether is converted into vapour, carrying)g off the heat to fill the vacuum. This is a positive proof that a vacuum will receive and retain in a latent state more heat than a plenum.
These principles may probably be applicable to useful purposes. For instance,
to cool wholesome water, such as that of the Mississippi, rendering it palatable
for drinking, to supply the city of New-Orleans; or of the Schuylkill to
supply the citizens of Philadelphia. A steam engine may work a large air-pump,
leaving a perfect vacuum behind it on the surface of the water at every
stroke. If ether be used as a medium for conducting the heat from the water
into the vacuum, the pump may force the vapour rising from the ether, into
another pump to be employed to compress it into a vessel immersed in water;
the heat will escape into the surrounding water, and the vapour return to
ether again; which being let into the vessel in the vacuum, it may thus
be used over and over repeatedly. Thus it appears possible to extract the
latent heat from cold water and apply it to boil other water; and to make
ice in large quantities in hot countries by the power of a steam engine.
I suggest these ideas merely for the consideration of those who may be disposed.
posed to investigate the principles, or wish them put in operation. And,
lest I should be thought extravagant, as was the case with the Marquis of
Worcester, I give a
DESCRIPTION OF THE MACHINE.
Make an air-pump and close the lower end of the cylinder by connecting it with a globular glass vessel, if metal will not answer as well: fix the lower end of the cylinder of this pump, so that the glass vessel shall be immersed in the water that is to be cooled, and which is to be contained ~ a tight vessel. Near to this pump fix another much smaller, called the condensing pump, and connect it with a small vessel, called the condenser, immersed in water, fixing
off from the water by the steam, composed from a very small part off the water, yet it is not the steam that contains the 1000 degrees of heat in a latent state, but the space which it occupies; this quantity of heat is necessary to heat up that large space to the temperature of 212 degrees; and the truth is, that only 212 degrees of heat are a necessary constituent part of steam, under the pressure of the atmosphere. It is true that if the heat that is carried off by the steam formed by 1 cubic inch of water expanded into 10,000 or 14,000 cubic inches space, was to be returned into 1000 cubic inches of water, it would raise the temperature of the whole mass 1 degree; but if the heat that is contained in 1 cubic inch of the space occupied by the steam, be returned into 1000 cubic inches of water, it appears by this statement that it would raise the temperature of the water but part of a degree.
The steam of boiling water exactly balances the weight of the atmospheie: if therefore we have occasion to fix a pump to raise hot water, we must place no dependence on the pressure of the atmosphere to force it up through the lower valve, (as it does when the water is cold) because the steam rising from water of the temperature of 212 degrees, will fill the vacuum that would be formed by the working of the pump, and exactly balance the pressure of the atmosphere and prevent the water from rising. In such cases the lower valve must be placed below the surface of the hot water that is to be raised.
Water boils in vaccum at the temperature of 70 deg. and vapour may by compression be reduced to the fluid from whence it arose: hence we may infer, that water will keep cooler in vacuum than when exposed to the pressure of the atmosphere. If an open glass vessel be filled with ether and set in water in vacuum, the ether will boil rapidly and rob the water of its latent heat until it freezes. It is not right to say that the ether becomes so cold that it freezes the water around it. The heat in the water enters the ether, causing
valve between them. Connect the upper end of these working cylinders
by a pipe with a valve therein at the top of the exhausting pump, and connect
the bottom of the condenser with the glass globe, by a small pipe, in which
insert a cock1 called the ether-cock. The piston rods of the pumps must
work through stuffing boxes made air-tight, and each piston must have a
valve fixed in it, one to shut downward and the other upward: work these
pistons by a lever that is to be put in motion by a steam engine or any
other power.
THE OPERATION.
Fill the glass globe with ether, ~o that the piston will touch its surface at every stroke; expel the air from the pumps and condenser, making a complete vacuum in them. Set the machine in motion and every time the piston rises the exhausting piston leaves a perfect vacuum behind it:
the ether then begins to boil and carry off the latent heat from the water; the steam of the ether fills the vacuum, which is again exhausted by the pump, and driven into the condensing pump which compresses it in the condenser, forcing out the heat which robs the vapour of its essential constituent part, and reduces it to ether again; the ether-cock being opened just sufficient to let the ether return to the glass globe to undergo the same operation; and so on ad infinitum. The machine might be simplified by connecting the top of the exhausting cylinder with the condenser, dispensing with the condensing cylinder and piston. The condensation might be sufficiently effected by the exhausting cylinder and piston alone forcing the vapour into the condenser. If the air not expelled it will be forced into the condenser, and remain above the ether formed there without injuring the working or the effect of the engine: but I presume the condensing pump would be necessary to carry the principle to such extent as to boil water by the heat extracted from cold water. A small pump may be fixed so as to be worked by the same
lever, to extract the water from the vessel as fast as 'necessary after
it is cooled. The vessel may be kept full by the pressure of the atmosphere
forcing the water through a valve at the bottom.
CONCLUSION.
Many persons think that new inventions and discoveries are made by accident, without labour or expense: some may have such a gift. It was a saying among the ancients that " truth lies in a well;" and may we not say that reason and experience are the means by which we draw it out. It has been by the most intense study that I have made discoveries. After having a faint glimpse of the principle, it was with may be and tedious.; steps that I attained a clear and distinct view. I received great assistance from the result of experiments made by others, which arc to b found in scientific work; and righted believed that if government would, at the expense of uncertainty, employ ingenious persons, in every art and science, to make with care every experiment that might possibly lead to the extension of our knowledge of principles, carefully recording the experiments and results so that they might be fully relied on, and leaving readers to draw their own inferences, the money would be well expended; for it would tend greatly to aid the progress of improvement in the arts and sciences.
I now conclude, and renounce all further pursuit of inventions and discoveries, at least until it shall appear clearly to be my interest; lamenting that it should so often prove unprofitable, and even ruinous as it has been to many. I at the same time believe, that more good frequently results to the community from intellectual than corporal labours; yet one pair of hands is worth two mechanical or philosophical heads to the individual himself. I purpose, however, to attend to the improvement of my steam engine, to render it suitable for the various purposes for which it may be required.