Maudslay, Sons, and Field's 16-horse beam engine. A 60-horse power rotative engine, by W. Fairbairn. Cross section and end view of a 60-horse power rotative engine by W. Fairbairn. Section and end view of one of the engines of the steam ship City of London. Engines of the steamers Clyde, Tweed, Tay, and Teviot. Design for a dredging machine. Samuda's bell-crank marine engine. Direct action engines. Double cylinder engines of H. M. steam vessel Retribution, of 800-horse power. PLATB 18. Oscillating engines of H.M. steamer Black Eagle, 260-horse power (side view), by J. Penn and Son. 19. Oscillating engines of H.M. steamer Black Eagle, 260-horse power (end view), by J. Penn and Son. 20. Projects for rotative steam engines. 21. Borrie's revolving engine. 22. Wood's rotatory engine. 23. Locomotive engine on the London and Birmingham Railway, by Edward Bury. 24. Locomotive engine, by Robert Stephenson and Co. 25. Details of the engines of the West India mail steam packets Clyde, Tweed, Tay, and Teviot. Plate 1. 26. Details of the engines of the West India mail steam packets Clyde, Tweed, Tay, and Teviot. Plate 2. 27. Details of the engines of the West India mail steam packets Clyde, Tweed, Tay, and Teviot. Plate 3. 28. Details of the engines of the West India mail steam packets Clyde, Tweed, Tay, and Teviot. Plate 4. 29. Feed engines for marine boilers. 30. Boilers of H.M. steam frigate Phoenix, by J. Penn and Son. . PRELIMINARY DISCOURSE. A TREATISE on the Steam Engine would, we suppose, hardly be reckoned orthodox if it began in any other way than with an account of the doings of Savery, Papin, and the other patriarchs whose names figure in the history of steam invention. The devices indeed of these ancient worthies bear very little resemblance to the modern steam engine, and can throw but little light upon its structure or mode of operation; but it was out of these primitive contrivances that the modern steam engine arose, and they derive a sufficient dignity from that relationship to make them the objects of a just curiosity. We think, therefore, that some slight sketch of the expedients employed in the early career of steam improvement is but a reasonable prelude to a Treatise on the Steam Engine, and is indeed indispensable to the integrity of such a work: But we fear our qualifications for the task are by no means so conspicuous, for delineations of this kind require a light and graceful pencil, and become intolerable in the hand of a vulgar limner. The great art lies in saying just as much as the necessity of the case requires, and nothing more; for a history of the steam engine is the least important part of a treatise on that subject, and only deserves a space answerable to its insignificance; whereas by needlessly expanding this part of the work, or by elaborating trivial schemes into importance, the proper subordination of objects is destroyed, and all those discriminating shades are obliterated which constitute the excellence of the picture. To all this we must add that people in these utilitarian days have neither time nor inclination to listen to long-winded descriptions of exploded projects in steam machinery, though they might like well enough to know something of the nature of those expedients if it can be told them in a few words: But they are not likely to perplex themselves with such inquiries as, who first forced water above its level by steam pressure, or solicited it to rise by a partial vacuum? and to say the truth, such inquiries appear to us of about as much importance as the researches of those learned grammarians, who spend a lifetime in restoring a dative case, or adjusting a metre or an The task, too, of resolving these frivolous problems is quite as tedious a one as that undertaken by the learned persons aforesaid; for after having ascended through history, by a most toilsome progress, to the first person guilty of disturbing the equanimity of water by steam pressure, the shade of some learned recluse who flourished in ancient times in China it may be, or Japan, will probably rise up with proofs of a still higher priority, and the idol just set up for universal adoration will be cast into the dust by this new authority, to be overthrown in its turn by the researches of subsequent enquirers. The fact appears to be, that the power of steam to raise water above its level was widely known in very ancient times, and appears to have been occasionally employed by the Greeks and Egyptians for trivial, or rather for unworthy, purposes: But it is in modern times only that steam has been adapted to ends of weight or utility, and the history of the steam engine properly begins with that application. accent. The facts with which we It is not to be expected that the historical narration on which we are about to enter should contain much that is new. must necessarily deal have often been stated before, and we believe now admit neither of much increase nor modification; but it is not impossible, we think, to set these facts in truer lights, and to deduce from them sounder conclusions than have yet been realised. It appears to us to be a vice of many commentators, that they have attached too much importance to the deeds of individual projectors, and have estimated at far too low a rate the current intelligence of the time, of which indeed the proficiency of those exalted persons is to be regarded as merely the exponent. They have set down the early progress of the steam engine as due altogether to the perspicacity and contrivance of a few solitary adventurers, without hinting that some part of it might reasonably be ascribed to that spread of information and general advancement of knowledge to which that progress is in The consequence of this fault is, that a host of truth mainly attributable. projectors are made to shine aloft like stars,' whose merit, when tested by the general information of their own time, fades into insignificance. They stand, it is true, in the van of improvement, but the elevation due to the -existing state of society is measured as a part of their intellectual stature ; and while they are each presented to the imagination like a precipice starting abruptly to the skies in solitary and awful majesty, they are in truth only to be regarded as so many heights, which, whatever be their absolute altitude, rise only a few feet above the other heights around them. It is absurd, therefore, to seek to elevate any of the early projectors of the as in the material world, the most precious productions are those which ment. But whatever be the merit that is due to these 'sons of notoriety,' it is we think divisible only among those of them who have been instrumental in working out some practically useful result. The mere men of speculation, who have suggested modes of doing things, but have never done them, are not to be ranked with those who have really accomplished something, in a case where the whole difficulty of the task lies in its practical achieveWhatever else these ingenious persons may be, they are certainly not among the number of the improvers of the steam engine; and their claims, if to be considered at all, ought in strictness to be considered as the claims of a distinct class of persons. Nor can the merit of such a class, under ordinary circumstances, be considerable, for there is nothing more easy than to originate vague ideas of improvement, though it is generally a very difficult thing to carry those ideas into successful practice. M. Arago, however, and his followers it seems, have set the steam engine down as a French invention, because Solomon de Caus first adopted the idea of steam as a motive force, and Papin suggested the application of the cylinder and piston. It would be as reasonable, in our apprehension, to set down the battle of Waterloo as a French victory, because Napoleon adopted the idea of fighting it; for the question in all such cases is, not who first adopted an ideal result, but who actually realised that result in practice. The scheme of Solomon de Caus was neither useful nor new, and Papin's project was so impracticable, that he himself abandoned it in favour of Savery's scheme. We have no evidence that either of those persons ever completed an engine of any kind. Papin's scheme, as he first proposed it, was worse than the previous project of the Marquis of Worcester, for it was without a boiler; and after several gyrations he certainly left the steam engine in as imperfect a state as if he had never meddled with the subject. If, therefore, we were disposed to retort upon M. Arago his pitiful nationality, we might with some plausibility say that his proofs only show the lamentable barrenness of the French intellect; for the very ideas which, in the minds of Englishmen, have quickly grown up to a rich maturity, and have blessed all nations with countless new enjoyments, have, when implanted in the minds of Frenchmen, invariably failed to produce any useful result. But this is idle. The steam engine happens, no doubt, to be from first to last an English invention; but that result, we conceive, is not so much to be attributed to the superior genius of the English people as to the force of circumstances, which made some such instrument as the steam engine more valuable to England than to other nations. If France had possessed valuable mines lying under water, and at the same time an abundance of coal ready to be made instrumental for their recovery, there is every reason to suppose that the steam engine would have been a French invention; and we think the consideration that our honours are the result merely of accident, ought to reconcile that ingenious people to a priority it is idle to contest. No nation can be expected to excel another nation of equal power and intelligence in every thing; and if it be the fact, as we willingly admit, that the French excel us in some things, they must be content to give us the palm in others, one of which certainly is steam engineering.-There is no end, however, of these speculations, and we fear they are neither very captivating nor very convincing; so that we shall here cut them short, and proceed without further preamble to the history of the invention. B The history of the steam engine is divisible into five great epochs. The first extends from the times of the ancients to the first effectual application of the boiler, which appears to have been accomplished by the Marquis of Worcester, and it was this single step that turned the toys of Hero and De Caus into a true and useful steam engine. The second epoch is distinguished by the employment of a vacuum as an aid to the simple pressure of the steam. The third epoch relates to the successful application of the cylinder. The fourth to the condensation of the steam by injection, to the movement of the valves by the engine, and to the various improvements in detail, which were carried into effect by Smeaton. The fifth epoch is that distinguished by the application of the condenser, and the other improvements of Watt, which brings down the history to our own times; as since the steam engine left the hand of Watt, no improvement involving a new principle has been added to the list. Under each of these heads we have a few observations to offer. FROM THE TIMES OF THE ANCIENTS TO THE INTRODUCTION OF THE FIRST FEASIBLE STEAM ENGINE. The ancients appear to have had very vague notions of the nature of steam. They believed in the existence of only four elements-fire, air, earth, and water; and thought that water was turned into air when dissipated by evaporation. Thus Plato says, "That which we now call water becomes as a stone, or solid, but being melted and diffused becomes gas or air;" and it was the prevalent notion of his time, and of many subsequent ages, that water is turned into air by heat. In consequence of this misconception, it is often difficult to understand, in the description of ancient pneumatic contrivances, whether steam or air was the moving power, and we have indeed generally to form our conclusion on this head from the nature of the arrangement. We have, however, very clear evidence that both steam, and air expanded by heat, were often used by the ancients as motive powers, and some of the expedients employed for that purpose are of considerable elegance. In a work which has been often referred to, entitled Spiritalia seu Pneumatica, written by Hero, a philosopher of Alexandria, about 130 years before the Christian era, a variety of devices are set forth for elevating liquids, and obtaining rotatory motion by means of air and steam, of which we shall only enumerate those in which it is beyond doubt steam was the agent. The first of these is a method of causing wine to flow from the hands of effigies set beside an altar, after the fire upon the altar has been lighted. A steam-tight vessel or vase, containing wine, is placed within each effigy, and the altar is made hollow, and is partly filled with water, bent pipes being conducted from the space above the water in the altar to the spaces above the wine in the vases, and other tubes again being led from beneath the level of the wine in the vases to the hands of the effigies. When, therefore, says Hero, you are about to sacrifice, you must pour into the tubes a few drops, lest they should be injured by heat, and attend to every joint, lest it leak; and so the heat of the fire mingling with the water will pass in an aerial state through these tubes to the vases, and pressing on the wine make it pass through the bent syphons, until, as it flows from the hands of the living creatures, they will appear to sacrifice as the altar continues to burn. The instrument for the production of rotatory motion is one of great ingenuity, and has all the qualities of a true and efficient steam engine, except its size. This instrument is called the Æolipile, and is identical in all its material features with the engines lately constructed by Avery in America, and Ruthven of Edinburgh, in this country. These engines are more expensive in steam than ordinary engines, and travel at an inconvenient speed; but in other respects they are quite as effectual, and their construction is extremely simple and inexpensive. The substance of Hero's recipe for the construction of an Eolipile is this. Let a boiler be set on the fire, and nearly filled with water, and let its mouth be closed by a cover which is pierced by a bent tube, whose extremity fits exactly into a hollow sphere. But at the opposite end of the diameter (of the sphere) let there be an iron axis supported from the top of the cover, and let the sphere have two bent pipes at the ends of a diameter of the sphere, perforated therewith, and bent round in opposite directions; and let the bends make right angles, and be in the plane perpendicular to the axis. Then it will follow that the boiler being heated, the vapour passing through the tubes into the sphere will rush out through the reversed pipes, and whirl the sphere round on its axis. Hero specifies another modification of this instrument for giving motion to automaton figures, so as to induce the idea of supernatural intervention among the superstitious multitude by whom the heathen temples were frequented; but here heated air, instead of steam, is made the primum mobile, in order that the inciting power may be invisible. There is no doubt that pneumatical contrivances were extensively employed by the priests in ancient times for deluding the people, and it is easy to conceive that such treatises as that of Hero, which discovered the nature of those pious frauds, must have been the occasion, at the time. of infinite scandal. The celebrated statue of Memnon, which uttered sounds every morning at sunrise, was, no doubt, indebted to some such artifice as one of those described by Hero for its mysterious power. Very few of the devices he mentions are of his own invention, but most of them existed for ages before his time, although the knowledge of their structure and mode of operation appears to have been confined chiefly to the priests. On the revival of classical learning throughout Gothic Europe the work of Hero attracted earnest attention, and several translations of it were made which afforded an early exercise to the infant art of printing. A knowledge of the expedients of the ancient mechanicians was thus widely diffused, and it was probably one of them that was reproduced in Spain in 1543 by Blasco de Garay, a sea-captain, for the propulsion of vessels. This contrivance, whatever may have been its real nature, appears to have been very effectual. Commissioners were appointed by the Emperor Charles V. to test the invention at Barcelona on the 17th of June 1543, and the result was that a ship of 200 tons burden was propelled by the machine at the rate of three miles an hour. Nothing further is known of the invention than that the vessel was propelled by paddle wheels, and that the moving force was derived from a boiler containing water, which, it was said, was liable to explode. It appears unaccountable that after the successful result realised by Garay, no further step should have been taken respecting his plan. He was rewarded by the Emperor, and promoted into a higher rank, but his ingenuity does not appear to have been ever turned to any useful account, and his scheme was never introduced into practice. The various works on mechanics, published about the close of the sixteenth century, are full of expedients for the elevation of water similar to those of Hero, but much less refined; and Baptista Porta, in his book on Pneumatics, published at Naples in 1601, incidentally makes mention of the following contrivance, not indeed as any discovery of his own, but merely as an arrangement of convenience, in an experiment for ascertaining the relative bulks of water and steam. "Construct a box of glass or tin, having a hole at the bottom through which is introduced the neck of a flask, containing one or two ounces of water, and let the neck of the flask be so luted to the bottom of the box that there be no leakage. Near the bottom of the box let a pipe ascend, but at such a distance from the bottom as to permit the water to get out, which pipe passing through the cover is to rise a short distance above it. The box is to be filled with water by an aperture which is afterwards to be closed up, steam tight. This being done, place the flask upon the fire, and as it becomes slowly heated, the water being gradually dissolved into air will press upon the water in the box, and acting forcibly against the water which issues through the pipe, will not escape: and if we continue the heat, the whole of the water subjected to it will be evaporated, and during such evaporation the air will constantly press upon the water in the box, and the water will constantly spring from it." A similar arrangement is mentioned in a work by Solomon de Caus, a native of Normandy, or at all events a Frenchman; not for the philosophical purpose mentioned by Porta, but merely as an illustration that water might be raised above its level by fire, a truth known from the remotest antiquity. The work of De Caus, to which we have referred, is entitled Les Raisons des Forces Mouvantes avec diverses Machines tant utiles que plaisantes, Paris, 1623. This work is dated Heidelberg, 1615, and the first edition appears to have been published at Frankfort: it contains the following among several other theorems of equal insignificance:—“ Take a ball of copper well soldered at every part; it must have a vent-hole to put in the water, and also a tube which is soldered to the top of the ball, the end of which approaches near to the bottom of the ball without touching it. After filling this ball with water through the vent-hole, stop it close and put it on the fire; then the heat striking against the ball will cause all the water to pass through the tube." De Caus also mentions a scheme of a solar fountain, but it, as well as the preceding, are merely clumsy imitations of some of the contrivances described by Hero. He gives the following illustration of the great force of steam:-"Take a ball of copper of one or two feet diameter, and one inch thick, which being filled with water by a small hole subsequently stopped by a peg, so that neither air nor water can escape, it is certain that if the said ball be put over a great fire so that it may become very hot, it will cause so violent a compression, that the ball will be shattered in pieces." The great force of steam, however, was very well known to the ancients, who even went the length of ascribing earthquakes to pent up vapours, generated by subterranean heat; and for ages the lime burners of Italy had been obliged to be careful of introducing hollow limestones into their kilns, as the water within them, when converted by the heat into steam, caused dangerous explosions. M. Arago, however, tells us that the ideas of the ancients respecting the force of steam had never reached any thing like the numerical appreciation realised by such experiments as those of De Caus. We confess that we are at a loss to understand wherein this numerical appreciation can consist, for although De Caus or Rivault may have ascertained that steam will burst a certain ball or bomb, they never ascertained what sort of ball or bomb steam will not burst, so that they did not establish any limit to the power of steam, but only showed that it is capable of very powerful effects. This, however, was known long previously; and in attributing to the force of pent up steam even such stupendous commotions as earthquakes-the upraising of continents and rending asunder of mountains-the ancients must have had at least quite as magnificent ideas of the force of that mighty agent as is to be afforded by the bursting of a ball or bomb, and we cannot perceive in what way an experiment establishes any thing which only proves that the power of an agent is adequate to the production of effects far more paltry than are known to be within the range of its capacity. A contrivance for obtaining a rotatory motion from steam is described by Giovanni Branca, in a work published at Rome in 1629, entitled Le Machine; volume nuovo et di multo artificio da fare effetti maravigliosi Preliminary Discourse. The Marquis of Worcester, Discovery of the Atmospheric Pressure. si tanto spiritali quanto di animale operatione. This contrivance consists of a wheel furnished with boards set round its periphery, after the manner of an undershot water wheel, against which a jet of steam proceeding from a boiler is made to impinge, thereby forcing the wheel into revolution. An engine on this plan would necessarily be very ineffectual, and would indeed be greatly inferior to the Æolipile of Hero, for although it is undoubtedly the fact that the power of steam issuing from an orifice is expended in giving velocity to its own particles, and ought therefore, theoretically speaking, to be again surrendered by those particles during impact, yet this result cannot be realised in practice, and the great velocity at which the wheel requires to travel, makes the scheme perilous and impossible. Mr. Pilbrow, however, has during the past year revived this species of engine, and has taken out a patent for the particular arrangement he proposes. His engine is described and delineated in the first volume of THE ARTIZAN, and the causes are there pointed out, with considerable fulness of detail, which must prohibit its success. The whole of the contrivances we have hitherto enumerated are mere mechanical toys, and although not incapable of useful applications, they appear only to have been employed to excite the wonder of the ignorant, and were never used for any serious purpose. To this judgment indeed the machinery of Blasco de Garay is an exception, for in that case, if the reports which have reached us may be relied upon, a useful result was undoubtedly realised. Yet this result contributed nothing to the success subsequently reached, and is rather an episode in the history of steam improvement, than a link in the chain of progress. The trial of De Garay's machinery indeed was a mere experiment, a successful one it is true, but one nevertheless which was barren in its effects, for in a few years all recollection of the achievement had become obliterated, and the contrivance, whatever might be its merits, was certainly never reduced to successful practice. It appears extremely probable that the machinery employed by De Garay was merely the ancient olipile on a superior scale of magnitude, for the low state of the mechanical arts in his time, and the small mechanical refinement to be expected of a sea-captain, equally discourage the idea that he should have reached any very exquisite or difficult kind of mechanism. It is idle, however, to speculate on such a subject, and we must therefore rest content with the certainty that the scheme of this enterprising person was never brought into practice, and that up to the epoch at which we have now arrived no useful application of steam power to the purposes of life had been accomplished. The next name on our list is the Marquis of Worcester, who in 1663 published a pamphlet addressed to King Charles II. and the English Parliament, entitled "A Century of the Names and Scantlings of the Marquis of Worcester's Inventions," with the view to obtain the aid of government for their prosecution. Among many ingenious and some fantastic and preposterous devices, we have the following fire water-work, "An admirable and most forcible way to drive up water by fire; not by drawing or sucking it upwards, for that must be as the philosopher calleth it 'infra sphæram activitatis,' which is but at such a distance, but this way hath no bounder if the vessel be strong enough; for I have taken a piece of whole cannon, whereof the end was burst, and filled it three quarters full of water, stopping and screwing up the open end, as also the touch-hole, and making a constant fire under it; within twenty-four hours it burst, and made a great crack, so that having a way to make my vessels so that they are strengthened by the force within them, and the one to fill after the other, I have seen the water run like a constant fountain stream, forty feet high. One vessel of water rarefied by fire driveth up forty of cold water, and a man that tends the work has but to turn two cocks that one vessel of water being consumed another begins to force and re-fill with cold water, and so successively; the fire being tended and kept constant, which the self-same person may likewise abundantly perform in the interim between the necessity of turning the said cocks." This is the first feasible scheme for raising water by steam power that history records, and it is in that application that the modern steam engine had its origin. Previous projectors had in no way improved upon the expedients described by Hero, and indeed in by far the majority of cases the movement had been retrograde; but in the Marquis of Worcester's contrivance we have an engine of respectable efficacy applied to a weighty purpose, and from his time the progress onward has never been interrupted, but improvement has followed upon improvement, until the steam-engine has become what we now find it. It is idle to say that the Marquis of Worcester's project was only a reproduction of that of De Caus. The instrument of De Caus was a mere toy, not intended, and certainly not adapted for any purpose of practical utility, whereas the Marquis of Worcester enumerates many important practical uses, to which his engine might be applied, and many of them it certainly would have been perfectly competent to compass. In another part of his Century he says that his water work "is by many years' experience and labour so advantageously by me contrived, that a child's force bringeth up an hundred foot high, an incredible quantity of water, even two foot diameter, so naturally, that the work will not be heard into the next room, and with so great ease and geometrical symmetry, though it work day and night from one end of the year to the other, it will not require forty shillings' reparation to the whole engine, nor hinder one day's work, and not only with little charge to drain all sorts of mines, and furnish cities with water though never so high seated, as well as to keep them sweet, running through several streets, and so performing 3 the work of scavengers, as well as furnishing the inhabitants with sufficient water for their private occasions." It appears very clear from these descriptions that the Marquis of Worcester not only had succeeded in making a powerful and effective engine, but had arrived at a very just conception of the important ends such a machine may be made to fulfil. None of the contrivances before his time were provided with means to make their action continuous, and the instrument of De Caus, so far from being adapted to raise water from a mine, or for the supply of towns, had merely the power of emptying itself of the boiling water with which it was filled. Indeed, it appears undeniable that the Marquis of Worcester was the first person, so far as our present knowledge extends, by whom "a water-commanding engine" of any power or utility was constructed, and he seems to have brought his contrivance to nearly all the perfection of which that species of engine is susceptible. There is no evidence that he made use of the atmospheric pressure as an aid to the final effect, but he seems perfectly conscious of the applicability of that agency, and indeed speaks as if such an application was very well understood in his time. We are not aware that there is any drawing extant of this machine; and the various hypothetical delineations of it that we have seen err, we think, in representing it as provided with only one boiler, for there could not in this kind of engine have been any feedpump, and in the absence of that instrument two boilers must have been indispensable to make the action of the engine continuous. Besides the description says, that "one vessel of water being consumed another begins to force, and refill with cold water," which we take to mean that when the water of one boiler was evaporated it was filled up with cold water, and the other was in the meanwhile put into operation; the water in the boiler last filled having again become hot before that in the other was exhausted. One of these engines appears to have been set up to draw water out of the Thames at Vauxhall, and is thus spoken of by Cosmo de Medici, who inspected it in 1653. "It raises water more than 40 geometrical feet by the power of one man only, and in a very short space of time will draw up four vessels of water through a tube or channel not more than a span in width, on which account it is considered to be of greater service to the public than the other machine near Somerset House," which last was one driven by two horses. We should be disposed to infer from this account, that the principle of the atmospheric pressure was employed in this engine, for it is difficult to see by what power, other than suction, the necessary rapidity of motion could be given to the water in the pipe leading from the river to the engine, and which would appear to be smaller than the pipes applied in other cases. We have now, then, brought the history of the steam engine down to the point at which its application to purposes of utility begins, and we believe most of our readers will concur with us in the opinion that the Marquis of Worcester's "water-commanding engine" was the first machine moved by fire of efficacy and permanence. To it, indeed, the pedigree of the modern steam engine is easily traceable, while between the epochs of Lord Worcester and of Hero nothing appears to have been contrived of novelty or merit in this department of ingenuity. We are not disposed, however, to attach any great merit even to Lord Worcester's contrivance, for it is deducible, without any great stretch of the imagination, from the schemes of Hero; and indeed there is very little doubt that the ancients would have realised a very effectual steam engine if they only had possessed mines that required to be drained, and coal to bestow on such a purpose. It is to the force of circumstances chiefly that the superior proficiency of the present age in such devices is to be ascribed; and we hold it vicious in principle to confound this impelling power with the ingenuity appertaining to particular inventors, and which nature dispenses with wonderful uniformity to all generations. FROM THE INTRODUCTION OF THE FIRST USEFUL STEAM ENGINE TO THE APPLICATION OF THE PRINCIPLE OF A VACUUM. We have already hinted our belief that the method of raising water by the action of the vacuum, or to speak more properly, by the atmospheric pressure, was not unknown to the Marquis of Worcester, and that in one of his engines erected at Vauxhall that agency was probably employed. We have no proof, however, that such was the case; and in the description of his engine in the "Century of Inventions," he certainly disclaims the use of a vacuum, at least as a chief agent. In the engine of Captain Savery, however, of which we must now say something, the plan of a vacuum is introduced with much effect, and instead of the water in his engine being forced up all the way by steam pressure, the receivers, or forcing vessels, are situated thirty feet above the level of the water, to which height the water is drawn by the vacuum created within them. As the principle of the atmospheric pressure is one which bears much upon this inquiry, it may be worth while to say a few words respecting it. It was maintained by the greater number of the ancient philosophers that the existence of a vacuum was impossible, and was abhorrent to nature. Galileo was the first to suspect that the horror attributed to nature was imaginary, or was at least confined within limits of no very wide range, for on the application of a pump to a very deep well sunk by the Grand Duke of Tuscany at Florence, it was found that the water would not rise more than thirty-two feet, leaving the upper part of the pipe empty, from which Galileo inferred that nature's horror of a vacuum |