VIADUCT, NEAR WATFORD, BIRMINGHAM RAIL-ROAD.
VIADUCT, NEAR WATFORD, BIRMINGHAM RAIL-ROAD.
THESTEAM ENGINE.
THE
STEAM ENGINE.
HERO OF ALEXANDRIA.
HERO OF ALEXANDRIA.
[Pg003]TOCINX
THE STEAM ENGINE, A SUBJECT OF POPULAR INTEREST.—THE OBJECT OF THIS WORK.—DISPUTES RESPECTING THE INVENTION.—HERO.—DE GARAY.—DE CAUS.—BRANCA.—MARQUIS OF WORCESTER.—PHYSICAL PRINCIPLES.—ELASTIC AND INELASTIC FLUIDS.—THEIR PROPERTIES.—APPLICATION OF THESE PRINCIPLES TO THE ENGINES OF HERO, DE CAUS, AND LORD WORCESTER.—SIR SAMUEL MORLAND.—PAPIN.—ATMOSPHERIC PRESSURE.—THE WEIGHT OF AIR.—LESS AT GREATER HEIGHTS.—BAROMETER.—PRESSURE OF AIR.—ELASTIC FORCE OF AIR AND GASES.—FORCE PRODUCED BY A VACUUM.—COMMON PUMP.—RAREFACTION BY HEAT.—PAPIN'S METHODS OF PRODUCING A VACUUM.—HIS DISCOVERY OF THE CONDENSATION OF STEAM.—SAVERY.
(1.)That the history of the invention of a piece of mechanism, and the description of its structure, operation, and[Pg004]uses, should be capable of being rendered the subject matter of a volume, destined not alone for the instruction of engineers or machinists, but for the information and amusement of the public in general, is a statement which at no very remote period would have been deemed extravagant and incredible.
Advanced as we are in the art of rendering knowledge popular, and cultivated as the public taste is in the appreciation of the expedients by which science ministers to the uses of life, there is still perhaps but one machine of which such a proposition can be truly predicated: it is needless to say that that machine is theSTEAM ENGINE. There are many circumstances attending this extraordinary piece of mechanism which impart to it an interest so universally felt. Whether we regard the details of its structure and operation, the physical principles which it calls into play, and the beautiful contrivances by which these physical principles are rendered available;—or, passing over thesemeans, we direct our attention to theendswhich they attain, we are equally filled with astonishment and admiration. The history of the steam engine offers to our notice a series of contrivances which, for exquisite and refined ingenuity, stand without any parallel in the annals of mechanical science. These admirable inventions, unlike other results of scientific inquiry, have also this peculiarity, that, to understand their excellence and to perceive their beauty, no previous or subsidiary knowledge is necessary, save what may be imparted with facility and clearness in the progress of the explanation and development of the machine itself. A simple and clear exposition, divested of needless technicalities and aided by well-selected diagrams, is all that is necessary to render the construction and operation of the steam engine, in all its forms, intelligible to persons of plain understanding and moderate information.
But if the contrivances by which this vast power is brought to bear on the arts and manufactures, be rendered attractive by their great mechanical beauty, how much more imposing will the subject become when the effects which the steam engine has produced upon the well-being of the human race are considered. It has penetrated the crust of the earth, and drawn from beneath it boundless treasures[Pg005]of mineral wealth, which, without its aid, would have been rendered inaccessible; it has drawn up, in measureless quantity, the fuel on which its own life and activity depend; it has relieved men from their most slavish toils, and reduced labour in a great degree to light and easy superintendence. To enumerate its present effects, would be to count almost every comfort and every luxury of life. It has increased the sum of human happiness, not only by calling new pleasures into existence, but by so cheapening former enjoyments as to render them attainable by those who before could never have hoped to share them: the surface of the land, and the face of the waters, are traversed with equal facility by its power; and by thus stimulating and facilitating the intercourse of nation with nation, and the commerce of people with people, it has knit together remote countries by bonds of amity not likely to be broken. Streams of knowledge and information are kept flowing between distant centres of population, those more advanced diffusing civilisation and improvement among those that are more backward. The press itself, to which mankind owes in so large a degree the rapidity of their improvement in modern times, has had its power and influence increased in a manifold ratio by its union with the steam engine. It is thus that literature is cheapened, and, by being cheapened, diffused; it is thus that Reason has taken the place of Force, and the pen has superseded the sword; it is thus that war has almost ceased upon the earth, and that the differences which inevitably arise between people and people are for the most part adjusted by peaceful negotiation.
Deep as the interest must be with which the steam engine will be regarded in every civilised country, it presents peculiar claims upon the attention of the people of Great Britain. Its invention and progressive improvement are the work of our own time and our own country; it has been produced and matured almost within the last century, and is the exclusive offspring of British genius, fostered and sustained by British enterprise and British capital.
The steam engine is a mechanical contrivance, by which coal, wood, or other fuel is rendered capable of executing any[Pg006]kind of labour.Coalsare by it made to spin, weave, dye, print and dress silks, cottons, woollens, and other cloths; to make paper, and print books upon it when made; to convert corn into flour; to express oil from the olive, and wine from the grape; to draw up metal from the bowels of the earth; to pound and smelt it, to melt and mould it; to forge it; to roll it, and to fashion it into every desirable form; to transport these manifold products of its own labour to the doors of those for whose convenience they are produced; to carry persons and goods over the waters of rivers, lakes, seas, and oceans, in opposition alike to the natural difficulties of wind and water; to carry the wind-bound ship out of port; to place her on the open deep ready to commence her voyage; to throw its arms around the ship of war, and place her side by side with the enemy; to transport over the surface of the deep persons and information, from town to town, and from country to country, with a speed as much exceeding that of the ordinary wind, as the ordinary wind exceeds that of a common pedestrian.
Such are the virtues, such the powers, which the steam engine has conferred uponCOALS. The means of calling these powers into activity are supplied by a substance which nature has happily provided in unbounded quantity in every part of the earth; and though it has no price, it has inestimable value: this substance isWATER.
A pint of water may be evaporated by two ounces of coals. In its evaporation it swells into two hundred and sixteen gallons of steam, with a mechanical force sufficient to raise a weight of thirty-seven tons a foot high. The steam thus produced has a pressure equal to that of common atmospheric air; and by allowing it to expand, by virtue of its elasticity, a further mechanical force may be obtained, at least equal in amount to the former. A pint of water, therefore, and two ounces of common coal, are thus rendered capable of doing as much work as is equivalent to seventy-four tons raised a foot high.
The circumstances under which the steam engine is worked on a railway are not favourable to the economy of fuel. Nevertheless a pound of coke burned in a locomotive engine[Pg007]will evaporate about five pints of water. In their evaporation they will exert a mechanical force sufficient to draw two tons weight on the railway a distance of one mile in two minutes. Four horses working in a stage-coach on a common road are necessary to draw the same weight the same distance in six minutes.
A train of coaches weighing about eighty tons, and transporting two hundred and forty passengers with their luggage, has been taken from Liverpool to Birmingham, and back from Birmingham to Liverpool, the trip each way taking about four hours and a quarter, stoppages included. The distance between these places by the railway is ninety-five miles. This double journey of one hundred and ninety miles is effected by the mechanical force produced in the combustion of four tons of coke, the value of which is about five pounds. To carry the same number of passengers daily between the same places by stage-coaches on a common road, would require twenty coaches and an establishment of three thousand eight hundred horses, with which the journey in each direction would be performed in about twelve hours, stoppages included.
The circumference of the earth measures twenty-five thousand miles; and if it were begirt with an iron railway, such a train as above described, carrying two hundred and forty passengers, would be drawn round it by the combustion of about thirty tons of coke, and the circuit would be accomplished in five weeks.
In the drainage of the Cornish mines the economy of fuel is much attended to, and coals are there made to do more work than elsewhere. A bushel of coals usually raises forty thousand tons of water a foot high; but it has on some occasions raised sixty thousand tons the same height. Let us take its labour at fifty thousand tons raised one foot high. A horse worked in a fast stage-coach pulls against an average resistance of about a quarter of a hundred weight. Against this he is able to work at the usual speed through about eight miles daily: his work is therefore equivalent to one thousand tons raised one foot. A bushel of coals consequently, as used in Cornwall, performs as much labour as a day's work of one hundred such horses.[Pg008]
The great pyramid of Egypt stands upon a base measuring seven hundred feet each way, and is five hundred feet high, its weight being twelve thousand seven hundred and sixty millions of pounds. Herodotus states, that in constructing it one hundred thousand men were constantly employed for twenty years. The materials of this pyramid would be raised from the ground to their present position by the combustion of about four hundred and eighty tons of coals.
The Menai Bridge consists of about two thousand tons of iron, and its height above the level of the water is one hundred and twenty feet. Its mass might be lifted from the level of the water to its present position by the combustion of four bushels of coal.
The enormous consumption of coals produced by the application of the steam engine in the arts and manufactures, as well as to railways and navigation, has of late years excited the fears of many as to the possibility of the exhaustion of our coal-mines. Such apprehensions are, however, altogether groundless. If the present consumption of coal be estimated at sixteen millions of tons annually, it is demonstrable that the coal-fields of this country would not be exhausted for many centuries.
But in speculations like these, the probable, if not certain progress of improvement and discovery ought not be overlooked; and we may safely pronounce that, long before such a period of time shall have rolled away, other and more powerful mechanical agents will supersede the use of coal. Philosophy already directs her finger at sources of inexhaustible power in the phenomena of electricity and magnetism. The alternate decomposition and recomposition of water, by magnetism and electricity, has too close an analogy to the alternate processes of vaporisation and condensation, not to occur at once to every mind: the development of the gases from solid matter by the operation of the chemical affinities, and their subsequent condensation into the liquid form, has already been essayed as a source of power. In a word, the general state of physical science at the present moment, the vigour, activity, and sagacity with which researches in it are prosecuted in every civilised[Pg009]country, the increasing consideration in which scientific men are held, and the personal honours and rewards which begin to be conferred upon them, all justify the expectation that we are on the eve of mechanical discoveries still greater than any which have yet appeared; and that the steam engine itself, with the gigantic powers conferred upon it by the immortal Watt, will dwindle into insignificance in comparison with the energies of nature which are still to be revealed; and that the day will come when that machine, which is now extending the blessings of civilisation to the most remote skirts of the globe, will cease to have existence except in the page of history.
(2.)The object of the present volume will be to deliver, in an easy and familiar style, an historical view of the invention of the steam engine, and an exposition of its structure and operation in the various forms in which it is now used, and of its most important applications in the arts of life, especially in transport by land and water. It is hoped that the details of these subjects may be rendered easily intelligible to all persons of ordinary information, whether urged by that natural and laudable spirit of inquiry awakened by contemplating effects on the material and social condition of our species, so rapid and so memorable as those which have followed the invention of the steam engine, and by the pleasure which results from the perception of the numerous instances of successful contrivances and beautiful applications of science to art which it unfolds,—or impelled by the exigencies of trade or profession to acquire an acquaintance with a machine on which, more than any other, the prosperity of our commercial and manufacturing interests depends. It will be our aim to afford to the former class all the information which they can require; and, if this work be not as comprehensive in its scope, and as minute in its details, as some of the latter may wish, it will at least serve as an easy and convenient introduction to other works more voluminous, costly, and detailed, but less elementary in their matter, and less familiar in their style.
In explaining the different forms of steam engine which have been proposed in the course of the progressive improvement[Pg010]of that machine from its early rude and imperfect state to its present comparatively perfect form, it will be necessary to advert to various physical phenomena and mechanical principles, which, however obvious to those who are conversant with matters of science, must necessarily be at least imperfectly known by the great majority of our readers. To refer for information on such topics to other works on Mechanics and general Physics, would be with most readers ineffectual, and with all unsatisfactory. In former editions of the present work, we consigned these necessary general principles of physics and mechanics to a preliminary chapter; but it appears, on the whole, more convenient not to remove the exposition of the principle from the place where its application is required. We shall therefore pause as we proceed, where these difficulties occur, to give such explanation and illustration as may seem best suited to render them intelligible and interesting to the unscientific reader.
The history of the arts and manufactures affords no example of any invention the credit for which has been claimed by so many different nations and individuals as that of the steam engine. The advocates of the competitors for this honour have urged their pretensions, and pressed their claims, with a zeal which has occasionally outstripped the bounds of discretion, and the contest has not unfrequently been tinged with prejudices, national and personal, and characterised by a degree of asperity altogether unworthy of so noble a cause, and beneath the dignity of science.
"When a question is clearly proposed, it is already half resolved." Let us see whether a careful attention to this maxim will aid us in the investigation of the origin of the steam engine. The source of the power of that machine is found in the following natural phenomena.
Such are the natural phenomena in which are found the original sources of all steam power. In some forms of steam engine one of these is used, and in some another, and in some the application of all of them is combined; but in no existing form of steam engine whatever is there any other source of mechanical power.
Neither these nor any other natural forces can be appliedimmediatelyto any useful purpose. The interposition of mechanism is indispensable; on the invention and contrivance of that mechanism depends altogether the useful application of these natural forces.
The world owes the steam engine then partly todiscovery, and partly toinvention.
He that discovered the fact, that mechanical force was produced in the conversion of water into steam, must be justly held to be a sharer in the merit of the steam engine, even though he should never have practically applied his discovery. The like may be said of him who first discovered the source of the mechanical power arising from the expansion of steam.
The discoverer of the fact, that steam being reconverted into water greatly contracted its dimensions, and thereby produced a vacuum, is likewise entitled to a share of the credit.[Pg012]
The mechanism by which these natural forces have been rendered so universally available as a moving power, is very various and complicated, and cannot be traced to one inventor. "If a watchmaker," says M. Arago, "well instructed in the history of his art, were required to give a categorical answer to the question, Who has invented watches? he would remain mute; but the question would be divested of much of its difficulty if he were required separately to declare who discovered the use of the main spring, the different forms of escapement, or the balance wheel." So it is with the steam engine. It is a combination of a great variety of contrivances, distinct from each other, which are the production of several inventors. If, however, one name more than the rest be entitled to special notice; ifheis entitled to the chief credit of the invention who by the powers of his mechanical genius has imparted to the steam engine that form, and conferred upon it those qualities, on which mainly depends its present extensive utility, and by which it has become an agent of transcendant power, spreading its beneficial effects throughout every part of the civilised globe, then the universal voice will, as it were by acclamation, award the honour to one individual, whose pre-eminent genius places him far above all other competitors, and from the application of whose mental energies to this machine may be dated those grand effects which render it a topic of interest to all for whom the progress of civilisation has any attractions. Before the era rendered memorable by the discoveries ofJames Watt, the steam engine, which has since become an object of such universal interest, was a machine of extremely limited power, inferior in importance and usefulness to most other mechanical agents used as prime movers; but, from that epoch, it is scarcely necessary here to state, that it became a subject not of British interest only, but one having an important connection with the progress of the human race.
Hero of Alexandria, 120 B. C.
Fig. 1.
Fig. 1.
(3.)The discovery of the fact, that a mechanical force is produced when water is evaporated by the application of heat,[Pg013]must be considered as the first capital step in the invention of the steam engine. It is recorded in a work entitledSpiritalia seu Pneumatica, that Hero of Alexandria contrived a machine, 120 years before the Christian era, which was moved by the mechanical force of the vapour of water. The principle of this machine admits of easy explanation: When a fluid issues from any vessel in which it is confined, that vessel suffers a force equal to that with which the fluid escapes from it, and in the opposite direction. If water issues from an orifice, a pressure is produced behind the orifice corresponding to the force with which the water escapes. If a man discharge a gun, the gases produced by the explosion of the powder issue with a certain force from the muzzle, and his shoulder is driven backwards by the recoil with a corresponding force. If the muzzle, instead of being presented forwards, were turned at right angles to the length of the gun, then, as the gases of explosion would escape sideways, the recoil would likewise take place sideways, and the shooter, instead of being driven backward, would be made to spin round as a dancer pirouettes. This was the principle of Hero's steam engine. A small globe or ball was placed on pivots atAandB(fig.1.), on which it was capable of revolving: steam was supplied through one of these pivots from one of the tubesD C E F, which communicated with the boiler. This steam filled the globeA I B K, and also the armsI HandK G. A lateral orifice, represented atG, near the end of these arms, allowed the steam to escape in a jet, and the reaction, producing a recoil, had a tendency to drive the arm round. A small orifice atH, on the other side of the tube, produced a like effect. In the same manner, any convenient number of arms might be provided, surrounding the globe and communicating with its interior like the spokes of a wheel. Thus these arms, having lateral orifices for the escape of the steam, all placed so that the recoil may[Pg014]tend to turn the globe in the same direction, a rotatory motion might be communicated to any machinery which it was desired to move.
After having been allowed to slumber for nearly two thousand years, this machine has recently been revived, and engines constructed similar to it are now working in these countries. In the proper place we shall describe Avery's Rotatory Engine, which it will be seen is, not only in its principle, but almost in its details, the machine ofHero of Alexandria.
Although the elastic force of steam was not reduced to numerical measure by the ancients, nor brought under control, nor applied to any useful purpose, yet it appears to have been recognised in vague and general terms. Aristotle, Seneca, and other ancient writers, accounted for earthquakes by the sudden conversion of water into steam within the earth. This change, according to them, was effected by subterranean heat. Such tremendous effects being ascribed to steam, it can scarcely be doubted that the Greeks and Romans were acquainted with the fact, that water in passing into vapour exercises considerable mechanical power. They were aware that the earthquakes, which they ascribed to this cause, exerted forces sufficiently powerful to extend the natural limits of the ocean; to overturn from their foundations the most massive monuments of human labour; to raise islands in the midst of seas; and to heave up the surface of the land of level continents so as to form lofty mountains.
Such notions, however, resulted not as consequences of any exact or scientific principles, but from vague analogies derived from effects which could not fail to have been manifested in the arts, such as those which commonly occurred in the process of casting in metal the splendid statues which adorned the temples, gardens, and public places of Rome and Athens. The artisan was liable to the same accidents to which modern founders are exposed, produced by the casual presence of a little water in the mould into which the molten metal is poured. Under such circumstances, the sudden formation of steam of an extreme pressure produces, as is well known, explosions attended with destructive effects. The Grecian[Pg015]and Roman artisans were subject to such accidents; and the philosopher, generalising such a fact, would arrive at a solution of the grander class of phenomena of earthquakes and volcanoes.
Before natural phenomena are rendered subservient to purposes of utility, they are often made to minister to the objects of superstition. The power of steam is not an exception to this rule. It is recorded in the Chronicles, that upon the banks of the Weser the ancient Teutonic gods sometimes marked their displeasure by a sort of thunderbolt, which was immediately succeeded by a cloud that filled the temple. An image of the godBusterich, which was found in some excavations, clearly explains the manner in which this prodigy was accomplished by the priests. The head of the metal god was hollow, and contained within it a pot of water: the mouth, and another hole, above the forehead, were stopped by wooden plugs; a small stove, adroitly placed in a cavity of the head under the pot, contained charcoal, which, being lighted, gradually heated the liquid contained in the head. The vapour produced from the water, having acquired sufficient pressure, forced out the wooden plugs with a loud report, and they were immediately followed by two jets of steam, which formed a dense cloud round the god, and concealed him from his astonished worshippers.[1]
Among other amusing anecdotes showing the knowledge which the ancients had of the mechanical force of steam, it is related that Anthemius, the architect of Saint Sophia, occupied a house next door to that of Zeno, between whom and Anthemius there existed a feud. To annoy his neighbour, Anthemius placed on the ground floor of his own house several close digesters, or boilers, containing water. A flexible tube proceeded from the top of each of these, which was conducted through a hole made in the wall between the houses, and which communicated with the space under the floors of the rooms in the house of Zeno. When Anthemius desired to annoy his neighbour, he lighted fires under his boilers, and the steam produced by them rushed in such quantity and with[Pg016]such force under Zeno's floors, that they were made to heave with all the usual symptoms of an earthquake.[2]
Blasco de Garay, A. D. 1543.
(4.)In the year 1826, M. de Navarrete published, in Zach's Astronomical Correspondence, a communication from Thomas Gonzales, Director of the royal archives of Simancas, giving an account of an experiment reported to have been made in the year 1543, in which a vessel was propelled by a machine having the appearance of a steam engine.
Blasco de Garay, a sea captain, proposed in that year to the Emperor Charles V. to propel vessels by a machine which he had invented, even in time of calm, without oars or sails. Notwithstanding the apparent improbability attending this project, the Emperor ordered the experiment to be made in the port of Barcelona, and the 17th of June, 1543, was the day appointed for its trial. The commissioners appointed by Charles V. to attend and witness the experiment were Don Henry of Toledo, Don Pedro of Cardona, the treasurer Ravago, the vice chancellor and intendant of Catalonia, and others. The vessel on which the experiment was made was the Trinity, 200 tons burthen, which had just discharged a cargo of corn at Barcelona. Garay concealed the nature of his machinery, even from the commissioners. All that could be discovered during the trial was, that it consisted of a large boiler containing water, and that wheels were attached to each side of the vessel, by the revolution of which it was propelled. The commissioners having witnessed the experiment, made a report to the king, approving generally of the invention, particularly on account of the ease and promptitude with which the vessel could be put about by it.
The treasurer Ravago, who was himself hostile to the project, reported that the machine was capable of propelling a vessel at the rate of two leagues in three hours; but the other commissioners stated that it made a league an hour at the least, and that it put the vessel about as speedily as would be accomplished with a galley worked according to the common[Pg017]method. Ravago reported that the machinery was too complicated and expensive, and that it was subject to the danger of the boiler bursting.
After the experiment was made, Garay took away all the machinery, leaving nothing but the framing of wood in the arsenals of Barcelona.
Notwithstanding the opposition of Ravago, the invention was approved, and the inventor was promoted and received a pecuniary reward, besides having all his expenses paid.
From the circumstance of the nature of the machinery having been concealed, it is impossible to say in what this machine consisted; but as a boiler was used, it is probable, though not certain, that steam was the agent. There have been various machines proposed, of which a furnace and boiler form a part, and in which the agency of steam is not used. The machine of Amontons furnishes an example of this. It is most probable that the contrivance of Garay was identical with that of Hero. The low state of the arts in Spain in the sixteenth century would be incompatible with the construction of any machine requiring great precision of execution. But the simplicity of Hero's contrivance would have rendered its construction and operation quite practicable. As to the claims to the invention of the steam engine advanced by the advocates of De Garay, founded on the above document, a refutation is supplied by the admission, that though he was rewarded and promoted by the government of the day, in consequence of the experiment, and although the great usefulness of the contrivance in towing ships out of port, &c., was admitted, yet it does not appear that a second experiment was ever tried, much less that the machine was ever brought into practical use.
Solomon de Caus, 1615.
(5.)Solomon De Caus was engineer and architect to Louis XIII., king of France, before the year 1612. In that year he entered the service of the Elector Palatine, who married the daughter of King James I., with whom he came to England. He was there employed by the Prince of Wales in ornamenting the gardens of his house at Richmond.[Pg018]During his sojourn in England he composed and published at London, in the same year, a Treatise on Perspective. This person was the author of a work entitled, "Les Raisons des Forces Mouvantes, avec diverses Machines tant utiles que plaisantes," which was apparently composed at Heidelburg, but published at Franckfort, in 1615. The same work was subsequently republished in Paris in 1623.
The treatise commences with definitions of what were then considered the four elements: earth, air, fire, and water. Air is defined to be a cold, dry, and light element, capable of compression, by which it may be rendered very violent. He says, "The violence will be great when water exhales in air by means of fire, and that the said air is enclosed: as, for example, take a ball of copper of one or two feet diameter, and one inch thick, which being filled with water by a small hole, which shall be strongly stopped with a peg, so that neither air nor water can escape, it is certain that if we put the said ball upon a great fire, so that it will become very hot, that it will cause a compression so violent, that the ball will burst in pieces, with a noise like a petard."
The effect which is here described is due to the combined pressure of the heated air contained in the ball and the high pressure steam raised from the water, but much more to the latter than to the former. It is evident, however, from the language of De Caus, that he ascribes the force entirely to the air, and seems to consider that the force of the air proceeded from the water which exhaled in it.
The first theorem is, "that the parts of the elements mix together for a time, and then each returns to its place" (the elements here referred to being apparently air and water). Upon this subject the following is an example: "Take a round vessel of copper, soldered close on every side, and with a tube, whereof one end approaches nearly to the bottom of the vessel, and the other end, which projects on the outside of the vessel, has a stop-cock; there is also a hole in the top of the vessel, with a plug to stop it. If this vessel will contain three pots of water, then pour in one pot of water, and place the vessel on the fire about three or four minutes, leaving the hole open; then take the vessel off the[Pg019]fire, and a little after pour out the water at the hole, and it will be found that a part of the said water has been evaporated by the heat of the fire. Then pour in one pot of water as before, and stop up the hole and the cock, and put the vessel on the fire for the same time as before; then take it off, and let it cool of itself, without opening the plug, and after it is quite cold pour out the water, and it will be found exactly the same quantity as was put in. Thus we see that the water which was evaporated (the first time that the vessel was put on the fire) is returned into water the second time when that vapour has been shut up in the vessel, and cooled of itself."
In the description of these experiments, the processes of evaporation and condensation are obscurely indicated; but there is no intimation that the author possessed any knowledge of the elastic force of steam. His theorem is, that the parts of the element water mix for a time with the parts of the element air; that fire causes this mixture, and that on removing the fire, and dissipating the heat, then the parts of the water mixed with air return to their proper place, forming again part of the water. There is no indication of achange of propertyof the water in passing into vapour. It is difficult to conceive, if De Caus had been aware that the vapour of water possessed the same violent force which he distinctly and in terms ascribes to air, or if he had been aware that in effect the vapour of the water produced by the fire was a fluid, possessing exactly the same mechanical qualities, and producing the same mechanical effects as air, that he would not have expressed himself clearly on the subject.
He proceeds to give another demonstration that heat will cause the particles of water to mix with those of air.
"After having put the measure of water into the vessel, and shut the vent-hole, and opened the cock, put the vessel on the fire, and put the pot under the cock; then the water of the vessel, raising itself by the heat of the fire, will run out through the cock; but about one sixth or one eighth part of the water will not run out, because the violence of the vapour which causes the water to rise proceeds from the[Pg020]said water; which vapour goes out through the cock after the water with great violence. There is also another example in quicksilver, or mercury, which is a fluid mineral, but being heated by fire, exhales in vapour, and mixes with the air for a time; but after the said vapour is cooled, it returns to its first nature of quicksilver. The vapour of water is much lighter, and therefore it rises higher," &c. &c.
In this second demonstration there appears to be some obscure indication of the force of steam in the words "because of the violence of the vapour which causes the water to rise," &c.
The fifth theorem is the following:—
"Water will mount by the help of fire higher than its level," which is explained and proved in the following terms:—
Fig. 2.
Fig. 2.
"The third method of raising water is by the aid of fire. On this principle may be constructed various machines: I shall here describe one. Let a ball of copper markedA; well soldered in every part, to which is attached a tube and stop-cock markedD, by which water may be introduced; and also another tube markedB C, which will be soldered into the top of the ball, and the lower endCof which shall descend nearly to the bottom of the ball without touching it. Let the said ball be filled with water through the tubeD, then shutting the stop-cockD, and opening the stop-cock in the vertical tubeB C, let the ball be placed upon a fire the heat acting upon the said ball will cause the water to rise in the tubeB C."
In the apparatus as here described, the space enclosed in the boiler above the surface of the water is filled with air. By the action of the fire, two effects are produced: first, the air enclosed above the water, being heated, acquires increased elasticity, and presses with a corresponding force on the surface of the water. By this means a column of water will be driven up the tubeA Bat such a height as will balance the elasticity of the heated air confined in the boiler; but besides[Pg021]this the water contained in the boiler being heated, will produce steam, which being mixed with air contained in the boiler, will likewise press with its proper elasticity on the surface of the water, and will combine with the air in raising a column of water in the tubeA B. In the above description of the machine, the force which raises the water in the tubeA Bis ascribed to the fire, no mention being made of the water, or of the vapour or steam produced from it having any agency in raising the water in the tubeA B.
Antecedently to the date of this invention, the effect of heat in increasing the elastic force of air was known, and so far as the above description goes, the whole operation might be ascribed to the air by a person having no knowledge whatever of the elasticity of steam. M. Arago, however, who, on the grounds of this passage in the work of De Caus, claims for him a share of the honour of the invention of the steam engine, contends that the agency of steam in this apparatus was perfectly known to De Caus, although no mention is made of steam in the above description, because in the second demonstration above quoted he uses the words, "the violence of the vapour which causes the water to rise proceeds from the said water; which vapour goes out from the cock after the water with great violence." By these words M. Arago considers that De Caus expresses the quality of elasticity proper to the vapour, and that the context justifies the inference, that to this elasticity he ascribed the elevation of the water in the tubeC B.
There appears to be some uncertainty attending the birthplace of De Caus. In theBiographie Universellehe is said to have been born and to have died in Normandy. M. Arago assigns Dieppe, or its neighbourhood, as his birthplace.
There was another engineer and architect, Isaac De Caus, a native of Dieppe, who published a work in folio, entitled "Nouvelle Invention de Lever l'Eau plus haut que sa Source, avec quelque Machines mouvantes, par le Moyen de l'Eau, et un Discours de la Conduite d'Icelle." This volume is without a date, but from the nature of its contents it would appear to have been published before the work of Solomon De Caus already cited. The drawings and machines described in both[Pg022]are exactly the same; but the definitions and theorems quoted above on raising water by fire are not given in the work of Isaac. It seems, therefore, that Solomon De Caus re-published, with additions, the work of Isaac De Caus. From the same birthplace being assigned to both these authors, as well as from the similarity of their pursuits, it is likely they were members of the same family, and from their christian names they were probably Jews.
The work cited above, was dedicated to Louis XIII., and in the dedication Solomon De Caus calls himself the subject of that monarch; and in the privilege prefixed to the work he is designated, "Our well-beloved Solomon De Caus, master engineer, being at present in the service of our dear and well-beloved cousin, the Prince Elector Palatine, has made known to us," &c.—"we, desiring to gratify the said De Caus, he being our subject," &c.
It is therefore certain, whatever may have been the birthplace of De Caus, that he was at least a subject of France. The circumstance of his work being written in French, though published beyond the Rhine, is also an argument in favour of his being a native of that country.
Giovanni Branca, 1629.
(6.)Giovanni Branca of Loretto in Italy, an engineer and architect, proposed to work mills of different kinds by steam issuing from a large æolopile, and blowing against the vanes of a wheel. Branca was the author of many ingenious mechanical inventions, a collection of which he dedicated to M. Cenci, the governor of Loretto. These were published in a work printed at Rome in 1629. It is a thin quarto, entitled "Le Machine volume nuovo, et di molto artificio da fare effetti maravigliosi tanto Spiritali quanto di Animale Operatione, arichito di bellissime figure. Del Sig. Giovanni Branca, Cittadino Romano. In Roma, 1629." The work contains sixty-three engravings, accompanied by descriptions in Italian and Latin. Branca's steam engine, represented in the twenty-fifth plate, consists of a wheel furnished with flat vanes upon its rim, like the boards of a paddle wheel. The steam is produced in a close vessel, and made to issue with violence from the extremity[Pg023]of a pipe directed against the vanes, and causes the wheel to revolve. This motion being imparted by the usual mechanical contrivances, any machinery may be impelled by it. Different useful applications of this power are contained in the work, viz. pestles and mortars for pounding materials to make gunpowder, and rolling stones for grinding the same; machines for raising water by buckets, for sawing timbers, for driving piles, &c. &c.
This method of applying the force of steam has no analogy to any application of steam in modern engines.
Edward Somerset, Marquis of Worcester, 1663.
(7.)Of all the names which figure in the early annals of steam, by far the most remarkable is that of the Marquis of Worcester, who has left a description of a machine in a work, entitled "The Scantling of One Hundred Inventions," which has been generally in this country considered as giving him a right to the honour of having been the inventor of the steam engine.
Lord Worcester having been engaged on the side of the Royalists in the civil wars of the revolution, lost his fortune, and went to Ireland, where he was imprisoned. He escaped from thence, and reached France; from that country he ventured to London, as a secret agent of Charles II., but was detected, and imprisoned in the Tower, where he remained until the restoration, when he was set at liberty. Tradition has connected the invention of the steam engine with the following anecdote:—One day, during his imprisonment, Lord Worcester observed the lid of the pot in which his dinner was being cooked, suddenly forced upwards by the vapour of the water which was boiling in it. Reflecting on this, it occurred to him that the same force which raised the cover of the pot might be rendered, when properly applied, a useful and convenient moving power. After he recovered his liberty, he accordingly proceeded to carry into effect this conception. The contrivance to which he was ultimately led is described in the following terms in the sixty-eighth invention, in the work above named:—
"I have invented an admirable and forcible way to drive[Pg024]up water by fire; not by drawing or sucking it upwards, for that must be, as the philosopher terms it,infra sphœrum activitatis, which is but at such a distance. But this way hath no bounder if the vessels be strong enough. For I have taken a piece of whole cannon whereof the end was burst, and filled it three quarters full of water, stopping and screwing up the broken end, as also the touch-hole, and making a constant fire under it; within twenty-four hours, it burst and made a great crack. So that, having a way to make my vessels so that they are strengthened by the force within them, and the one to fill after the other, I have seen the water run like a constant fountain stream forty feet high. One vessel of water rarefied by fire driveth up forty of cold water, and a man that tends the work has but to turn two cocks; that one vessel of water being consumed, another begins to force and refill with cold water, and so successively; the fire being tended and kept constant, which the self-same person may likewise abundantly perform in the interim between the necessity of turning the said cocks."
Since the date of the publication of the "Century of Inventions" was the year 1663, the experiments here mentioned must have been made before that year. The description of the machine here given, as well as others in the same work, was intended by the author, not to convey a knowledge of the nature of the mechanism which he used, but only to express the effects produced, and to indicate the physical principle on which they depended. It should also be observed, that an air of mystery was thrown by Worcester over the accounts of all the machines which he described; and therefore any obscurity in the above description ought not to be regarded as an evidence against his claim to the discovery of the mechanical agency of steam, so far as that agency is indicated by the effects said by him to be produced. The above account is, however, sufficiently distinct and explicit to enable any one possessing a knowledge of the mechanical qualities of steam to perceive the general nature of the machine described. To render this machine, and that of De Caus, previously described, intelligible to those who are not familiar with physical science, we must here explain some general principles on which their agency depends.[Pg025]