Chapter 5

The many varieties of the world's manufactures--one might almost call them wonders--are now so numerous, that to bring any particular one in a single form before this meeting is a matter of no easy nature. To-night, however, I have ventured to single out, and have the pleasure of bringing before you, the steam-engine, as the prime mover at present of our workshops and manufactories, as also the grand motive power of our railways, now so different from the time when the great Stephenson was said to be mad, because he thought it possible to drive a train at fifteen miles an hour. For the first serviceable use of this grand machine we are indebted to the great James Watt. He it was who first wrought it so as to be under the useful and entire control of man, from what it was in the time of Hero of Alexandria, about 120 years before Christ. Our engineers have, since Watt's time, improved upon it year by year, till at the present day, instead of having to go in a mail-coach from London to Edinburgh, which formerly took fifty hours, we now go in the express train in ten, a distance of 420 miles. If beyond this ten hours, we grumble, and ask guards, porters, &c., at the various stations, "What has made the train so late to-day?" forgetting that just before the railways were first opened, the great Stephenson was urged not to say too much as to the supposed power of the locomotive, in case the cause of railways might be damaged. This was only some forty years ago, and it shows us how times are changed, for in the present day we consider thirty miles an hour anything but a fast train.

The history of the steam-engine is a subject on which so much has been written in books and magazines now before the public, that what I am about to offer, though pretending nothing new, yet I hope may be looked upon as containing something useful as well as instructive, both to the practical and the amateur mechanic. I shall therefore, in as small a compass as possible, trace the steam-engine from its first and early stages up to its present perfect state as our grand motive power. The first mention made of the vapour of water, as formed by the action of heat upon it, is found to be as far back as 120 B.C., when one Hero of Alexandria employed this vapour for the purpose of driving a machine. It is a well-known fact that when water is brought up to a certain degree of heat, called the boiling-point, that it sends forth a vapour, the elastic properties of which, when in an open vessel, are not perceived--as, for instance, in a common pan--yet if the vessel is closed or shut up at the top, you will find that the vapour acquires such a degree of elastic force, that, if not allowed to escape by fair means, it would soon make a way or vent for itself by bursting whatever vessel it was contained in. Steam is thus highly elastic, but when separated from the fluid out of which it is generated, it does not possess a greater elastic force than the same quantity of air. If, for example, a vessel is filled with steam only at 212°, it may be brought to a red heat without fear of bursting; but if water is also in the vessel, each additional quantity of heat causes a fresh quantity of steam to be generated, which adds its elastic force to that of the steam already in the vessel, till the constantly accumulating force at last bursts the vessel.

This elastic vapour is called steam, and it is by this that that most beautiful machine, the steam-engine, is driven. As you all know, by this vapour or air--for it is invisible till it loses part of its heat--enormous power is obtained in a small compass, and the labour of man reduced to nothing compared with former ages. Many men laboured to perfect machinery to be worked by this vapour of water, and many came near the mark; but it remained for the great Watt, at the Soho Works, Birmingham, to bring the engine to its useful and working state, for though discovered as a motive power 120 B.C., it was yet reserved for this truly great man to be what may be termed the inventor of the steam-engine.

In 120 B.C., Hero of Alexandria made a machine to be driven by steam. It consisted of a hollow sphere into which the steam was admitted; projecting from the sphere were two arms, from which the steam escaped by three holes on the side of _each_ arm opposite to that of the direction of its revolution, which, by removing the power from off the one part of _each_ arm, caused it to revolve in the direction opposite to that of the hole that allowed the steam to escape. This kind of engine has been for some years in use by Mr. Ruthven of Edinburgh. There are others who have followed very closely on Hero's plan in more ways than one; for instance, it is the common Barker's mill, though with this difference, that his mill is driven by water instead of steam: Avery, also, made a steam-engine almost exactly the same. I may here, perhaps, just be allowed to mention what a little water and coal will produce, as it will show at once from whence our power is derived. "A pint of water may be evaporated by two ounces of coal; in its evaporation it swells to 216 gallons of steam, with a mechanical force equal to raising a weight of thirty-seven tons one foot high." A pound of coal in a locomotive will evaporate about five pints of water, and in their evaporation these will exert a force equal to drawing two tons on a railway a distance of one mile in two minutes. A train of eighty tons weight will take 240 passengers and luggage from Liverpool to Birmingham and back, each journey about four and a quarter hours; this double journey of 190 miles being effected by the combustion of one and a half tons of coke, worth about twenty-four shillings. To perform the same work by common road would require twenty coaches, and an establishment of 3800 horses, with which the journey would be performed each way in about twelve hours, stoppages included. So much for the advantages of steam.

The Romans are supposed to have had some knowledge of the power of steam. Among amusing anecdotes, showing the knowledge the ancients had of steam, it is told that Anthemius, the architect of Saint Sophia, lived next door to Zeno. There existed a feud between them, and to annoy his neighbour, Anthemius had some boilers placed in his house containing water, with a flexible tube which he could pass through a hole in the wall under the floor of Zeno's dwelling; he then lit a fire, which soon caused steam to pass through the tube in such a quantity as to make the floors to heave as if by an earthquake. But to return. We next come to Blasco de Garay (A.D. 1543), who proposed to propel a ship by the power of steam. So much cold water seems to have been thrown on his engine, that it must have condensed all his steam, as little notice is taken of it except that he got no encouragement. We find that it has also been used by some of the ancients in connection with their deities. Rusterich, one of the Teutonic gods, which was found in an excavation, proves how the priests deceived the people. The head of this one was made of metal and contained a pot of water. The mouth and another hole in the forehead being stopped by wooden plugs, a fire of charcoal was lighted under this pot of water, and at length the steam drove out the plugs with a great noise, and the god was shrouded in a mist of steam which concealed him from his astonished worshippers.

In 1629, Giovanni Branca of Loretto in Italy, an engineer and architect, proposed to work mills and other machinery by steam blowing against vanes, much in the same way as water does in turning a wheel. The waste of steam in such a plan is so obvious, that it is not to be wondered at that it did not produce any great results, as we all know that the moment we let steam out of his case, the case is all up with him, and he dies a natural death. He is a most delicate yet powerful agent, and requires to be kept warm in all weathers--this fact does not seem to have struck Mons. Branca when he let him out of his boiler.

The next person we come to, and perhaps the first of any note, is the Marquis of Worcester in 1663 (died 1667). He was a man who seems, as far as history tells us, to have taken a great interest in furthering the advancement of steam. He was not contented with one invention, but published a book entitled "A Century of Inventions," and in this work he describes a means of raising water by the pressure of steam. The Marquis appears to have been a politician as well as an inventor, as we find he was 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. Escaping to France, from thence he returned to London as a secret agent of Charles II., but was detected and imprisoned in the Tower, where he remained till the Restoration, when he was set at liberty. One day, while in prison, he observed the lid of the pot in which his dinner was being prepared lifted up by the vapour of the water boiling inside. Reflecting on this, he turned his mind to the matter, and thought that this vapour, if rightly applied, might be made a useful moving power. He thus describes his invention in his 68th Article: "I have contrived an admirable way to drive up water by fire, not by drawing or sucking it upwards, thirty-two feet. But this way hath no bounds, if the vessels be strong enough." He then goes on to say, that "having a way to make his vessels, so that they are strengthened by the force within, I have seen the water run like a constant stream forty feet high. One vessel rarified by fire driveth forty of cold water, and one being consumed, another begins to force, and refill with cold water, and so on successively, the fire being kept constant. The engineman having only to turn two cocks, so as to connect the steam with the one or the other vessel."

In this engine, if it can be called an engine, we see that the Marquis had a good idea of the power of steam, but he had none, you will observe, as to the action of the condensation which would immediately take place when the steam from the boiler was brought into contact with the cold water to be raised. Therefore this plan would be most expensive, on account of the great loss of steam by condensation. It was, however, quite able to produce the effect, though only equal to raising 20 cubic feet of water, or 1250 lbs., one foot high by one pound of coal, or about the two-hundredth part of the effect of a good steam-engine. After this, of course, it proved of no avail; but still we may say that the Marquis of Worcester was among the first who tried to make, and did do so, steam a moving power.

Our next is Denys Papin (died 1710), a native of Blois, in France, who was mathematical professor at Marpurg. To him is due the discovery of one of the qualities of steam--its condensation, so as to produce a vacuum, to the proper management of which our modern engines owe much of their efficacy. Papin seems to have been the first who conserved the idea of the cylinder and piston, which he made to act on atmospheric principles--that is to say, he took a cylinder with a piston moving up and down in it, and found that by removing the air from under the piston in the cylinder, that the pressure of the atmosphere would drive it down to the bottom of the cylinder: this he performed by admitting steam, and then condensing it rapidly, so causing the required vacuum. The pressure of the atmosphere is as near as may be 16 lbs. on every square inch of surface on the globe: this is obviously the weight of the columns of air extending from that square inch of surface upwards to the top of the atmosphere. This force is thus measured: Take a glass tube 32 inches long, open at one end and closed at the other; provide also a basin full of mercury; let the tube be filled with mercury and inverted into the basin. The mercury will then fall in the tube, till it gets to that height which the atmosphere will sustain. This is nothing more than the barometer used in all our houses. If the action of the tube be equal to a square inch, the weight of the column of mercury in the tube would be exactly equal to the weight of the atmosphere on each square inch of surface. Thus Papin discovered a great step in the steam-engine, though it was not much acted on for some years; he was also the first who proposed to drive ships with paddles worked by steam.

We now come to Thomas Savory, who got a patent in 1698 for a method of condensing steam to form a vacuum. Savory describes his discovery in this way:--Having drank a flask of wine at a tavern, he flung the empty flask on the fire, and then called for a basin of water to wash his hands. A little wine remained in the flask, which of course soon boiled, and it occurred to him to try what effect would be produced by putting the mouth of the flask into the cold water. He did this, and in a moment the cold water rushed up and filled the flask, this being caused by the steam being condensed and leaving a vacuum, which Nature abhors, and rather than permit this the water rushed up and took the place formerly occupied by the now condensed steam. We see by this in how simple a way great ends are produced, and in the age in which this happened, the result may be indeed be said to have produced a great end. The engine of Savory was used for some years as a machine to raise water. The principle of his engine was just as I have stated, and consisted of two cases and other various parts, and this engine possessed advantages over that of the Marquis of Worcester in sucking up the water as well as forcing.

Savory's engine consisted of two steam vessels connected to a boiler by tubes; a suction pipe, or that pipe which leads from a pump of the present day to the well, and communicating with each of the steam vessels by valves opening upwards; a pipe going from these steam vessels to any required height to which the water is to be raised. The steam vessels were connected to this pipe by other valves, also opening upwards, and by pipes. Over the steam vessels was placed a cistern, which was kept filled with _cold_ water. From this proceeded a pipe with a stopcock. This cistern was termed the condensing cistern, and the pipe could be brought over each steam vessel alternately from the boiler. Now, suppose the tubes to be filled with common air, and the regulator placed so that one tube and the boiler are made to communicate, and the other tube and the boiler closed, steam will fill one of the steam vessels through one tube; at first it will condense quickly, but erelong the heat of the steam will impart its heat to the metal of the vessel, and it will cease to condense. Mixed with the heated air, it will acquire a greater force than the air outside the valve, which it will force open, and drive out the mixture of air and steam, till all the air will have passed from the vessel, and nothing but the vapour of water remain. This done, a cock is opened, and the water from the cistern is allowed to flow over the outside of the steam vessel, first having stopped the further supply of steam from it; this produced the immediate condensation of the steam contained in it, by the temperature being brought down again by the cold water, and the condensation thus produced caused a vacuum inside the vessel. The valve will then be kept closed by the atmosphere outside, and the pressure of the air on the surface of the water in the well or reservoir will open another valve, force the water up the pipe, till, after one or two exhaustions--if I may so term it--it will at last reach the second vessel. Thus far the atmosphere has done all the work, but at last the water fills the vessel, and then comes the forcing point. Now the power of the steam itself is used to drive the water up the pipe. The steam is again let into the vessel, now filled in whole, or at least in great part, with water; at first it will, as before, condense rapidly, but soon the surface of the water will get heated, and as hot water is lighter than cold, it will keep on the surface, and the pressure of the steam from the boiler will drive all the water from the vessel up the pipe. When it is empty the cock is again opened, and the steam, which the vessel by this time only contains, is again condensed, and the same process which I have just described is again commenced and carried out, thus making Savory's engine a complete pump by the aid of the vapour of water as raised by fire.

Savory had the honour of showing this engine to His Majesty William III. at Hampton Court Palace, and to the Royal Society. He proposed the following uses, which perhaps may as well be mentioned, as they show how little was then known of the real value of the power of steam:--1. To raise water to drive mill-wheels--fancy erecting a steam engine now, of say fifty horse-power, to raise water to turn a wheel of say thirty; 2. To supply palaces and houses with water; 3. Towns with water; 4. Draining marshes; 5. Ships; 6. Draining mines. There is one more thing I may mention as curious, that though the steam he used must have been of a high pressure, he did not use a safety-valve, though it had been invented about the year 1681 by Papin. The consumption of fuel was enormous in Savory's engine, as may easily be perceived from the great loss of steam by condensation. Nevertheless, it was on the whole a good and a workable engine, as we find the following said of it by Mr. Farey:--"When comparison is made between Captain Savory's engine and those of his predecessors, the result will be favourable to him as an inventor and practical engineer. All the details of his invention are made out in a masterly style, so as to make it a real workable engine. His predecessors, the Marquis of Worcester, Sir S. Morland, Papin, and others, only produced outlines which required to be filled up to make them workable."

I must not detain you much longer before I proceed to the great Watt, but I will just name Newcomen, who invented an engine with a cylinder, and introduced a beam, to the other end of which he fixed a pump rod like a common or garden pump. He made the weight of the pump and beam to lift the piston, and then let the steam enter below the piston and condensed it by a jet of water, thus causing a vacuum, when the pressure of the atmosphere drove the piston from the top to the bottom of the cylinder and lifted the pump rods in the usual way. There were various cocks to be opened and shut in the working of this engine for the right admission of steam and water at the required moments, a task which was performed by boys who were termed cock-boys. I will now mention an instance which, though in practice not to be imitated, yet was one of those happy accidents which sometimes turn out for the best. One of these boys, like many, more fond of play than work, got tired of turning these cocks day by day, and conceived the idea of making the engine do it for itself. This idle boy--we will not call him good-for-nothing, as he proved good for a great deal in one way--was named Humphrey Potter, and one day he fixed strings to the beam, which opened and shut the valves, and so allowed him to play, little thinking this was one of the greatest boons he could possibly have bestowed on the world at large, for by so doing he rendered the steam-engine a self-acting machine.

We now come to a period which was destined to advance the cause of steam to a far greater extent--in fact, the time which rendered the steam-engine the useful and valuable machine it now is. This is the time of James Watt. This great man, be it said to the credit of Scotland, was born in Greenock, on the Clyde, on the 19th January 1736. His grandfather was a farmer in Aberdeenshire, and was killed in one of the battles of Montrose. His father was a teacher of mathematics, and was latterly chief magistrate of Greenock. James Watt, the celebrated man of whom I now speak, was a very delicate boy, so much so, that he had to leave school on account of his health, and was allowed to amuse himself as he liked. This he did in a scientific way, however, as an aunt of his said to him one day: "Do you know what you have been doing? You have taken off and put on the lid of the teapot repeatedly; you have been holding spoons and saucers over the steam, and trying to catch the drops of water formed on them by it. Is it not a shame so to waste your time?" Mrs. Muirhead, his aunt, was little aware that this was the first experiment in the way which afterwards immortalised her nephew.

In 1775 Watt was sent to London to a mathematical instrument maker, but could not stay on account of his health, and soon afterwards came back to Glasgow. He then got rooms in the College, and was made mathematical instrument maker to the University, and he afterwards opened a shop in the town. He was but twenty-one years of age when he was appointed to this post in the College, and his shop became the lounge of the clever and the scientific. The first time that his attention was directed to the agency of steam as a power was in 1734, when a friend of his, Mr. Robinson, who had some idea of steam carriages, consulted him on the subject,--little is said of this, however. In 1762 Watt tried some experiments on high-pressure steam, and made a model to show how motion could be obtained from that power; but did not pursue his experiments on account of the supposed danger of such pressure. He next had a model of Newcomen's engine, which would not work well, sent him to repair. Watt soon found out its faults, and made it work as it should do. This did not satisfy him, and setting his active mind to work, he found in the model that the steam which raised the piston had of course to be got rid of. This, as a natural consequence, caused great loss of heat, as the cylinder had to be cooled so as to condense the steam; and this led him at last, after various plans, to adopt a separate vessel to condense this steam. Of course, if you wish to save fuel, it is necessary that the steam should enter a heated cylinder or other vessel, or else all the steam is lost,--or in other words, condensed,--that enters it, until it has from its own heat imparted so much to the cylinder as to raise it to its own temperature, when it will no longer condense, and not till then does it begin to exert its elastic power to produce motion. This was the great object gained by James Watt, when, after various experiments, he gave up the idea altogether of condensing steam in its own or working cylinder, and then made use of a separate vessel, now called the condenser.

The weight of steam is about 1800 times less than water. I may here perhaps mention also that water will boil at 100 degrees Fahr. in vacuo, whereas in atmosphere it takes 212 degrees to boil. There is also a thing perhaps worth knowing to all who wish to get the most stock out of bones, &c., that if they are boiled in a closed vessel, that is to say, under a pressure of steam, a very large increase in quantity of the stock will be produced, because the heat is increased. A cubic inch of water, evaporated under _ordinary_ atmospheric pressure, will be converted into a cubic foot of steam; and a cubic inch of water, evaporated as above, gives a mechanical force equal to raising about a ton a foot high.