THE supreme hour of Watt's life was now about to strike. He had become deeply interested in the subject of steam, to which Professor Robison had called his attention, Robison being then in his twentieth year, Watt three years older.

Robison's idea was that steam might be applied to wheel carriages. Watt admitted his ignorance of steam then. Nevertheless, he made a model of a wheel carriage with two cylinders of tin plate, but being slightly and inaccurately made, it failed to work satisfactorily. Nothing more was heard of it. Robison soon thereafter left Glasgow. The demon Steam continued to haunt Watt. He, who up to this time had never seen even a model of a steam engine, strangely discovered in his researches that the university actually owned a model of the latest type, the Newcomen engine, which had been purchased for the use of the natural philosophy class. One wonders how many of the universities in Britain had been so progressive. That of Glasgow seems to have recognised at an early day the importance of science, in which department she continues famous. The coveted and now historical model had been sent to London for repairs. Watt urged its prompt return and a sum of money was voted for this purpose. Watt was at last completely absorbed in the subject of steam. He read all that had been written on the subject. Most of the valuable matter those days was in French and Italian, of which there were no translations. Watt promptly began to acquire these languages, that he might know all that was to be known. He could not await the coming of the model, which did not arrive until 1763, and began his own experiments in 1761. How did he obtain the necessary appliances and apparatus, one asks. The answer is easy. He made them. Apothecaries' vials were his steam boilers, and hollowed-out canes his steam-pipes. Numerous experiments followed and much was learnt. Watt's account of these is appended to the article on "Steam and the Steam Engine" in the "Encyclopdia Britannica," ninth edition.

Detailed accounts of Watt's numerous experiments, failures, difficulties, disappointments, and successes, as one after the other obstacles were surmounted, is not within the scope of this volume, these being all easily accessible to the student, but the general reader may be interested in the most important of all the triumphs of the indefatigable worker—the keystone of the arch. The Newcomen model arrived at last and was promptly repaired, but was not successful when put in operation. Steam enough could not be obtained, although the boiler seemed of ample capacity. The fire was urged by blowing and more steam generated, and still it would not work; a few strokes of the piston and the engine stopped. Smiles says that exactly at the point when ordinary experimentalists would have abandoned the task, Watt became thoroughly aroused. "Every obstacle," says Professor Robison,"was to him the begin" fling of a new and serious study, and I knew he would not quit it until he had either discovered its worthlessness or had made something of it." The difficulty here was serious. Books were searched in vain. No one had touched it. A course of independent experiments was essential, and upon this he entered as usual, determined to find truth at the bottom of the well and to get there in his own way. Here he came upon the fact which led him to the stupendous result. That fact was the existence of latent heat, the original discoverer of which was Watt's intimate friend, Professor Black. Watt found that water converted into steam heated five times its own weight of water to steam heat. He says:

Being struck with this remarkable fact (effect of latent heat), and not understanding the reason of it, I mentioned it to my friend, Dr. Black, who then explained to me his doctrine of latent heat, which he had taught some time before this period (1764); but having myself been occupied with the pursuits of business, if I had heard of it I had not attended to it, when I thus stumbled upon one of the material facts by which that beautiful theory is supported.

Here we have an instance of two men in the same university, discovering latent heat, one wholly ignorant of the other's doings; fortunately, the later discoverer only too glad to acknowledge and applaud the original, and, strange to say, going to him to announce the discovery he had made. Watt of course had no access to the Professor's classes, and some years before the former stumbled upon the fact, the theory had been announced by Black, but had apparently attracted little attention. This episode reminds us of the advantages Watt had in his surroundings. He breathed the very "atmosphere" of scientific and mechanical investigation and invention, and had at hand not only the standard books, but the living men who could best assist him.

What does latent heat mean? we hear the reader inquire. Let us try to explain it in simple language. Arago pronounced Black's experiment revealing it as one of the most remarkable in modern physics. Water passed as an element until Watt found it was a compound. Change its temperature and it exists in three different states, liquid, solid, and gaseous—water, ice and steam. Convert water into steam, and pass, say, two pounds of steam into ten pounds of water at freezing point and the steam would be wholly liquified, i. e., become water again, at 212°, but the whole ten pounds of freezing water would also be raised to 212° in the process. That is to say two pounds of steam will convert ten pounds of freezing water into boiling water, so great is the latent heat set free in the passage of steam to lower temperatures at the moment when the contact of cold surfaces converts the vapor from the gaseous into the liquid state. This heat is so thoroughly merged in the compound that the most delicate thermometer cannot detect a variation. It is undiscoverable by our senses and yet it proves its existence beyond question by its work. Heat which is obtained by the combustion of coal or wood, lies also in water, to be drawn forth and utilised in steam. It is apparently a mere question of temperature. The heat lies latent and dead until we raise the temperature of the water to 212°, and it is turned to vapor. Then the powerful force is instantly imbued with life and we harness it for our purposes.

The description of latent heat which gave the writer the clearest idea of it, and at the same time a much-needed reminder of the fact that Watt was the discoverer of the practically constant and unvarying amount of heat in steam, whatever the pressure, is the following by Mr. Lauder, a graduate of Glasgow University and pupil of Lord Kelvin, taken from "Watt's "Discoveries of the Properties of Steam."

It is well to distinguish between the two things, Discovery and Invention. The title of Watt the Inventor is world-wide, and is so just and striking that there is none to gainsay. But it is only to the few that dive deeper that Watt the Discoverer is known. When his mind became directed to the possibilities of the power of steam, he, following his natural bent, began to investigate its properties. The mere inventor would have been content with what was already known, and utilised such knowledge, as Newcomen had done in his engine. Watt might have invented the separate condenser and ranked as a great inventor, but the spirit of enquiry was in possession of him, and he had to find out all he could about the nature of steam.

His first discovery was that of latent heat. When communicating this to Professor Black he found that his friend had anticipated him, and had been teaching it in lectures to his students for some years past. His next step was the discovery of the total heat of steam, and that this remains practically constant at all pressures. Black's fame rests upon his theory of latent heat; Watt's fame as the discoverer of the total heat of steam should be equally great, and would be no doubt had his role of inventor not overshadowed all his work.

This part of Watt's work has been so little known that it is almost imperative to-day to give some idea of it to the general reader. Suppose you take a flask, such as olive oil is often sold in, and fill with cold water. Set it over a lighted lamp, put a thermometer in the water, and the temperature will be observed to rise steadily till it reaches 212', where it remains, the water boils, and steam is produced freely. Now draw the thermometer out of the water, but leaving it still in the steam. It remains steady at the same point-212°. Now it requires quite a long time and a large amount of heat to convert all the water into steam. As the steam goes off at the same temperature as the water, it is evident a quantity of heat has escaped in the steam, of which the thermometer gives us no account. This is latent heat.

Now, if you blow the steam into cold water instead of allowing it to pass into the air, you will find that it heats the water six times more than what is due to its indicated temperature. To fix your ideas: suppose you take 100 lbs. of water at 60°, and blow one pound of steam into it, making 101 lbs., its temperature will now be about 72°, a rise of 12°. Return to your 100 lbs. of water at 60° and add one pound of water at 212° the same temperature as the steam you added, and the temperature will only he raised about 2°. The one pound of steam heats six times more than the one pound of water, both being at the same temperature. This is the quantity of latent heat, which means simply hidden heat, in steam.

Proceeding further with the experiment, if, instead of allowing the steam to blow into the water, you confine it until it gets to some pressure, then blow it into the water, it takes the same weight to raise the temperature to the same degree. This means that the total heat remains practically the same, no matter at what pressure.

This is James Watt's discovery, and it led him to the use of high-pressure steam, used expansively.

Even coal may yet be superseded before it is exhausted, for as eminent an authority as Professor Pritchett of the Massachusetts Institute of Technology has said in a recent address:

Watt's invention and all it has led to is only a step on the way to harnessing the forces of nature to the service of man. Do you doubt that other inventions will work changes even more sweeping than those which the steam engine has brought?

Consider a moment. The problem of which Watt solved a part is not the problem of inventing a machine, but the problem of using and storing the forces of nature which now go to waste. Now to us who live on the earth there is only one source of power—the sun. Darken the sun and every engine on the earth's surface would soon stop, every wheel cease to turn, and all movement cease. How prodigal this supply of power is we seldom stop to consider. Deducting the atmospheric absorption, it is still true that the sun delivers on each square yard of the earth's surface, when he is shining, the equivalent of one horse-power working continuously. Enough mechanical power goes to waste on the college campus to warm and light and supply all the manufactories, street railroads and other consumers of mechanical power in the city. How to harness this power and to store it—that is the problem of the inventor and the engineer of the twentieth century, a problem which in good time is sure to be solved.

Who shall doubt, after finding this secret source of force in water, that some future Watt is to discover other sources of power, or perchance succeed in utilising the superabundant power known to exist in the heat of the sun, or discover the secret of the latent force employed by nature in animals, which converts chemical energy directly into the dynamic form, giving much higher efficiencies than any thermo-dynamic machine has to-day or probably ever can have. Little knew Shakespeare of man's perfect power of motion which utilises all energy! How came he then to exclaim "What a piece of work is man; how infinite in faculty; "in form and moving how express and admirable"? This query, and a thousand others, have arisen; for we forget Arnold's lines to the Master:

"Others abide our question. Thou art free.
We ask and ask—thou srnilest and art still."

Man's "moving" is found more "express and admirable" than that of the most perfect machine or adaptation of natural forces yet devised. Lord Kelvin says the animal motor more closely resembles an electro-magnetic engine than a heat engine, but very probably the chemical forces in animals produce the external mechanical effects through electricity and do not act as a thermo-dynamic engine.

The wastage of heat energy under present methods is appalling. About 65 per cent, of the heat energy of coal can be put into the steam boiler, and from this only 15 per cent, of mechanical power is obtained. Thus about nine-tenths of the original heat in coal is wasted. Proceeding further and putting mechanical power into electricity, only from 2 to 5 per cent, is turned into light; or, in other words, from coal to light we get on an average only about one-half of i per cent, of the original energy, a wastage of ninety-nine and one-half of every hundred pounds of coal used. The very best possible with largest and best machinery is a little more than one pound from every hundred consumed.

When Watt gave to the steam-engine five times its efficiency by utilising the latent heat, he only touched the fringe of the mysterious realm which envelops man. Burbank, of the spineless cactus and new fruits, who has been delving deep into the mysteries, tells us:

The facts of plant life demand a kinetic theory of evolution, a slight change from Huxley's statement that, "Matter is a magazine of force," to that of matter being force alone. The time will come when the theory of "ions" will be thrown aside, and no line left between force and matter."

Professor Matthews, he who, with Professor Loeb at Wood's Hole, is imparting life to sea-urchins through electrical reactions, declares "that certain chemical substances coming together under certain conditions are "bound to produce life. All life comes through the it of universal laws." We are but young in all this mysterious business. What lies behind and probably near at hand may not merely revolutionise material agencies but human preconceptions as well. "There are more things in Heaven and Earth than are ever dreamt of in your Philosophy."

Latent Heat was a find indeed, but there remained another discovery yet to make. Watt found that no less than four-fifths of all the steam used was lost in heating the cold cylinder, and only one-fifth performed service by acting on the piston. Prevent this, and the power of the giant is increased fourfold. Here was the prize to contend for. Win this and the campaign is won. First then, what caused the loss? This was soon determined. The cylinder was necessarily cooled at the top because it was open to the air, and also cooled below in condensing the charge of steam that had driven the piston up in order to create a vacuum, without which the piston would not descend from top to bottom, to begin another upward stroke. A jet of cold water was introduced to effect this. How to surmount this seemingly insuperable obstacle was the problem that kept Watt long in profound study.

Many plans were entertained, only to be finally rejected. At last the flash came into that teeming brain like a stroke of lightning. Eureka! he had found it. Not one scintilla of doubt ever intruded thereafter. The solution lay right there and he would invent the needed appliances. His mode of procedure, when on the trail of big game, is beautifully illustrated here. When he found the root of the defect which rendered the Newcomen engine impracticable for general purposes, he promptly formulated the one indispensable condition which alone met the problem, and which the successful steam-engine must possess. He abandoned all else for the time as superfluous, since this was the key of the position. This is the law he then laid down as an axiom—which is repeated in his specification for his first patent in 1769: "To make a perfect steam it was necessary that the cylinder should be always as hot as the steam which entered it, and that the steam should be cooled below 100 degrees to exert "its full powers."

Watt describes how at last the idea of the "separate "condenser," the complete cure, flashed suddenly upon his mind:

I had gone to take a walk on a fine Sabbath afternoon, early in 1765. I had entered the green by the gate at the foot of Charlotte Street and had passed the old washing-house. I was thinking upon the engine at the time, and had gone as far as the herd's house, when the idea came into my mind that as steam was an elastic body it would rush into a vacuum, and if a communication were made between the cylinder and an exhausted vessel it would rush into it, and might be there condensed without cooling the cylinder. I then saw that I must get rid of the condensed steam and injection-water if I used a jet as in Newcomen's engine. Two ways of doing this occurred to me. First, the water might be run off by a descending pipe, if an offlet could be got at the depth of thirty-five or thirty-six feet, and any air might be extracted by a small pump. The second was to make the pump large enough to extract both water and air. . . . I had not walked farther than the golf-house when the whole thing was arranged in my mind.

Professor Black says, "This capital improvement flashed upon his mind at once and filled him with "rapture." We may imagine "Then felt he like some watcher of the skies "When a new planet sweeps into his ken."

A new world had sprung forth in Watt's brain, for nothing less has the steam engine given to man. One reads with a smile the dear modest man's deprecatory remarks about the condenser in after years, when he was overcome by the glowing tributes paid him upon one occasion and hailed as having conquered hitherto uncontrollable steam. He stammered out words to the effect that it came in his way and he happened to find it; others had missed it; that was all; somebody had to stumble upon it. That is all very well, and we love thee, Jamie Watt (he was always Jamie to his friends), for such self-abnegation, but the truth of history must be vindicated for all that. It proclaims, Thou art the man; go up higher and take your seat there among the immortals, the inventor of the greatest of all inventions, a great discoverer and one of the noblest of men!

In this one change lay all the difference between the Newcomen engine, limited to atmospheric pressure, and the steam engine, capable of development into the modern engine through the increasing use of the tremendous force of steam under higher pressures, and improved conditions from time to time.

Watt leads the steam out of the cylinder and condenses it in a separate vessel, leaving the cylinder hot. He closes the cylinder top and sends a circular piston (hitherto all had been square) through it, and closely stuffs it around to prevent escape of steam. The rapidity of the "strokes" gained keeps the temperature of the cylinder high; besides, he encases it and leaves a space between cylinder and covering filled with steam. Thus he fulfils his law: "The cylinder is kept as hot as the "steam that enters." "How simple!" you exclaim. "Is "that all? How obviously this is the way to do it!" Very true, surprised reader, but true, also, that no condenser and closed cylinder, no modern steam engine.

On Monday morning following the Sabbath flash, we find Watt was up betimes at work upon the new idea. How many hours' sleep he had enjoyed is not recorded, but it may be imagined that he had several visions of the condenser during the night. One was to be made at once; he borrowed from a college friend a brass syringe, the body of which served as a cylinder. The first condenser vessel was an improvised syringe and a tin can. From such an acorn the mighty oak was to grow. The experiment was successful and the invention complete, but Watt saw clearly that years of unceasing labor might yet pass before the details could all be worked out and the steam engine appear ready to revolutionise the labor of the world. During these years, Professor Black was his chief adviser and encouraged him in hours of disappointment. The true and able friend not only did this, but furnished him with money needed to enable him to concentrate all his time and strength upon the task.

Most opportunely, at this juncture, came Watt's marriage, to his cousin Miss Miller, a lady to whom he had long been deeply attached. Watt's friends are agreed in stating that the marriage was of vast importance, for he had not passed untouched through the days of toil and trial. Always of a meditative turn, somewhat prone to melancholy when without companionship, and withal a sufferer from nervous headaches, there was probably no gift of the gods equal to that of such a wife as he had been so fortunate as to secure. Gentle yet strong in her gentleness, it was her courage, her faith, and her smile that kept Watt steadfast. No doubt he, like many other men blessed with an angel in the household, could truly aver that his worrying cares vanished at the doorstep.

Watt had at last, what he never had before, a home. More than one intimate friend has given expression to the doubt whether he could have triumphed without Mrs. Watt's bright and cheerful temperament to keep him from despondency during the trying years which he had now to encounter. Says Miss Campbell:

I have not entered into any of the interesting details my mother gave me of Mr. Watt's early and constant attachment to his cousin Miss Miller ; but she ever considered it as having added to his enjoyment of life, and as having had the most beneficial influence on his character. Even his powerful mind sank occasionally into misanthropic gloom, from the pressure of long-continued nervous headaches, and repeated disappointments in his hopes of success in life. Mrs. Watt, from her sweetness of temper, and lively, cheerful disposition, had power to win him from every wayward fancy; to rouse and animate him to active exertion. She drew out all his gentle virtues, his native benevolence and warm affections.

From all that has been recorded of her, we are justified in classing Watt with Bassanio.

"It is very meet
He live an upright life,
For having such a blessing in his lady,
He finds the joys of heaven here on earth;
And if on earth he do not merit it,
In reason he should never come to heaven."

Watt knew and felt this and let us hope that, as was his duty, he let Mrs. Watt know it, not only by act, but by frequent acknowledgment.

Watt did not marry imprudently, for his instrument-making business had increased, as was to have been expected, for his work soon made a reputation as being most perfectly executed. At first he was able to carry out all his orders himself; now he had as many as sixteen workmen. He took a Mr. Craig as a partner, to obtain needed capital. His profits one year were $3,000. The business had been removed in 1760 to new quarters in the city, and Watt himself had rented a house outside the university grounds. Having furnished it, Watt brought his young wife and installed her there, July, 17 64. We leave him there, happy in the knowledge that he is to be carefully looked after, and, last but not least, steadily encouraged and counselled not to give up the engine. As we shall presently see, such encouragement was much needed at intervals.

The first step was to construct a model embodying all the inventions in a working form. An old cellar was rented, and there the work began. To prepare the plan was easy, but its execution was quite another story. Watt's sad experience with indifferent work had not been lost upon him, and he was determined that, come what may, this working model should not fail from imperfect construction. His own handiwork had been of the finest and most delicate kind, but, as he said, he had "very little experience of mechanics "in great." This model was a monster in those days, and great was the difficulty of finding mechanics capable of carrying out his designs. The only available men were blacksmiths and tinsmiths, and these were most clumsy workmen, even in their own crafts. Were Watt to revisit the earth to-day, he would not easily find a more decided change or advance over 1764, in all that has been changed or improved since then, than in this very department of applied mechanics. To-day such a model as Watt constructed in the cellar would be simple work indeed. Even the gasoline or the electric motor of to-day, though complicated far beyond the steam model, is now produced by automatic machinery. Skilled workmen do not have to fashion the parts. They only stand looking on at machinery—itself made by automatic tools—performing work of unerring accuracy. Had Watt had at his call only a small part of the inventor's resources of our day, his model steam engine might have been named the Minerva, for Minerva-like, it would have sprung forth complete, the creature of automatic machinery, the workmen meanwhile smilingly looking on at these slaves of the mechanic which had been brought forth and harnessed to do his bidding by the exercise of godlike reason.

The model was ready after six months of unceasing labor, but notwithstanding the scrupulous fastidiousness displayed by Watt in the workmanship of all the parts, the machine, alas, "snifted at many openings." Little can our mechanics of to-day estimate what "perfect joints" meant in those days. The entire correctness of the great idea was, however, demonstrated by the trials made. The right principle had been discovered; no doubt of that. Watt's decision was that "it must be followed to an issue." There was no peace for him otherwise. He wrote (April, 1765) to a friend, "My whole thoughts are bent on this machine. I can "think of nothing else." Of course not; he was hot in the chase of the biggest game hunter ever had laid eyes on. He had seen it, and he knew he had the weapons to bring it down. A larger model, free as possible from defects which he felt he could avoid in the next, was promptly determined upon. A larger and better shop was obtained, and here Watt shut himself up with an assistant and erected the second model. Two months sufficed, instead of six required for the first. This one also at first trial leaked in many directions, and the condenser needed alterations. Nevertheless, the engine accomplished much, for it worked readily with ten and one-half pounds pressure per square inch, a decided increase over previous results. It was still the cylinder and its piston that gave Watt the chief trouble. No wonder the cylinder leaked. It had to be hammered into something like true lines, for at that day so backward was the art that not even the whole collective mechanical skill of cylinder-making could furnish a bored cylinder of the simplest kind. This is not to be construed as unduly hard upon Glasgow, for it is said that all the skill of the world could not do so in 1765, only one hundred and forty years ago. We travel so fast that it is not surprising that there are wiseacres among us quite convinced that we are standing still.

We may be pardoned for again emphasising the fact that it is not only for his discoveries and inventions that Watt is to be credited, but also for the manual ability displayed in giving to these "airy nothings "of the brain, a local habitation and a name," for his greatest idea might have remained an "airy nothing," had he not been also the mechanician able to produce it in the concrete. It is not, therefore, only Watt the inventor, 'Watt the discoverer, but also Watt, the manual worker, that stands forth. As we shall see later on, he created a new type of workmen capable of executing his plans, working with, and educating them often with his own hands. Only thus did he triumph, laboring mentally and physically. Watt therefore must always stand among the benefactors of men, in the triple capacity of discoverer, inventor, and constructor.

The defects of the cylinder, though serious, were clearly mechanical. Their certain cure lay in devising mechanical tools and appliances and educating workmen to meet the new demands. An exact cylinder would leave no room for leakage between its smooth and true surface and the piston; but the solution of another difficulty was not so easily indicated. Watt having closed the top of the cylinder to save steam, was debarred from using water on the upper surface of the piston as Newcornen did, to fill the interstices between piston and cylinder and prevent leakage of steam, as his piston was round and passed through the top of the cylinder. The model leaked badly from this cause, and while engaged trying numerous expedients to meet this, and many different things for stuffing, he wrote to a friend, "My old White Iron it is dead." This being the one he had trained to be his best mechanic, was a grievous loss in those days. Misfortunes never come singly; he had just started the engine after overhauling it, when the beam broke. Discouraged, but not defeated, he battled on, steadily gaining ground, meeting and solving one difficulty after another, certain that he had discovered how to utilise steam.