cylinder with a vessel of cold water. A quantity of this water was then introduced into the cylinder, under the piston, where it condensed the steam more or less completely, and created a vacuum more or less perfect; in consequence of which the piston was pressed down by the weight of the atmospheric air resting upon it, and carried down with it the end of the horizontal beam to which it was attached. When it had subsided as low as was desired, it opened the steam valve, and let in the steam under the piston, which was raised as before, and again pressed down by the weight of the air, on the steam being again condensed by the introduction of cold water. This operation went on continually, and thus an ascending and descending motion was produced, which was communicated by the horizontal beam to the whole machinery. The defect of this engine at length began to be observed. It consisted in the cooling of the cylinder by the cold water let in to condense the steam. The cylinder being thus rendered colder than steam, a considerable portion of the steam introduced was condensed by this coldness, while the piston was rising; and was thus destroyed before it had done its office. This rendered a greater generation of steam necessary, and of course a greater consumption of fuel. The steam, too, was not suddenly or perfectly condensed, so as to let the piston descend with sufficient rapidity or force; by which the power and effect of the machine were diminished. The water, also, into which the steam had been converted by condensation, remained in the bottom of the 1822. Evans V. Eaton. 1822. Evans V. Eaton. cylinder, and further impeded the descent of the piston. These defects were seriously felt in a country where fuel was dear, and became continually more and more so. At length they threatened to render the engine entirely useless, by creating a greater expense in fuel than could be compensated by the labour saving power of the machine. Then Watt arose, who, after long reflection and many experiments, conceived the happy idea of condensing the steam in a vessel different from that in which it was to perform its office. This he effected by connecting with the machine another vessel called a connector, which was connected with the cylinder by a pipe with a valve in it. This valve being opened by the motion of the machine, at the same moment when the piston had ascended to its greatest height, the steam rushed through it into the conductor, where it met a stream of cold water, introduced by the same means which had been before employed for letting it into the cylinder. This cold water condensed it as fast as it came in ; and a pump was also contrived, to work by the motion of the machine, and drew out of the conductor all the steam that remained uncondensed and all the water produced by the condensation. Thus a most perfect vacuum was created in the condenser, and consequently in the cylinder connected with it; the piston descended with freedom, rapidity, and force; and the cylinder, not being touched or affected by the cold water, retained a heat equal to that of steam: so that no portion of the steam introduced into it, was condensed too soon. This was the great improvement; but others were employed to increase its effect. The cylinder was surrounded by a case the best calculated to retain heat, and the space between this case and the cylinder was kept full of steam or boiling water. Thus the cylinder was kept in the hottest possible state; the state best adapted to the preservation of the steam, while performing its office and as steam thus preserved was found to be more effectual than atmospheric air in bringing down the piston, the top of the cylinder was closed, and steam was introduced above the piston as well as below it. This steam was conducted into the condenser, and there condensed and pumped out, in the same manner with that introduced below and thus the piston being alternately pressed up and down, by the elastic power of steam, in its most efficacious condition, gave a most powerful, steady, and uniform motion to the engine. Oily substances were employed instead of water, in keeping the vessels air tight; especially the top of the cylinder, where the steam of the piston played through it. Thus the machine was rendered as perfect as it seems capable of becoming. Now, in what does this machine differ from the steam engine of Newcomen, which was in use before? Both had a boiler to produce the steam, and a cylinder to receive it. The piston was the same in both, and connected in the same manner with the horizontal beam, for the purpose of communicating the motion to the rest of the machinery. In both the piston was raised by the expansive power of the steam; this steam, after its office had been performed, was condensed by cold water, so as to create a 1822. Evans V. Eaton. 1822. Evans V. Eaton. vacuum in the cylinder, and permit the piston to descend; and in both pipes and valves of the same construction was used, for introducing alternately the steam and the cold water. In what, then, did they differ? Merely in a new modus operandi, by which, with the addition of another vessel, the cold water was prevented from cooling the cylinder, while it conducted the steam; and the steam was made to operate in forcing the piston down, as well as in forcing it up. In this new modus operandi, produced by a different arrangement and construction of the old machines, with the addition of one new vessel, to receive and condense the steam, consisted the great invention of Watt; for which he obtained his patent, avowedly as for a new invention, or in the language of the British statute, a "new manufacture," and not for an improvement. His specification is inserted at length in 8 T. R. 96. note (a) where it will appear that he speaks of his discovery as a new invention, and not as an improvement, and never once mentions or alludes to the old machine. In what did this new discovery consist? I answer with the two judges of the Common Pleas in England who were in favour of this patent, and one of whom was Lord Chief Justice Eyre," and with the four Judges of the King's Bench, who were unanimous on the point,' that it consisted in the new principle on which the steam was condensed, and which was carried into effect by a new combination of the old machinery, with the addition of one new instru a Boulton v. Bull, 2 H. Bl. 463. b 8 T. R. 95. ment. The word "principle," as used in relation to this subject, is not taken in its general philosophical sense, where it means a law of motion or a property of matter; but in what may he termed its mechanical sense, in which it signifies a method of doing a thing, or of effecting a purpose, in other words, a modus operandi. It is therefore established by this solemn and elaborate decision of six English Judges against two, after repeated arguments and great consideration, that a new principle, or modus operandi carried into practical and useful effect by the use of new instruments, or by a new combination of old ones, with or without the addition of one or more new ones, is an original invention for which a patent may be supported, without reference to any former invention or machine, for performing the same or a similar operation. This may be taken as a maxim which the cases referred to will be found fully to support. Let us now apply this maxim to the patent of Oliver Evans. We shall soon see that according to the doctrine thus established, his discovery was not a mere "improvement," as the Court below pronounced it to be, but an original invention. The learned counsel here produced two models, one of Evans' Hopperboy, and one of Stouffer's, and explained minutely the difference between their principles, or modus operandi, which consisted in this: that in Stouffer's Hopperboy, the arms through a square mortice in which the square upright post was made to pass, were carried round by means of the upright post pressing upon the sides of the square 1822. Evans V. Eaton. |