Second Patent

The number and activity of rivals attracted to the steam engine and its possible improvement, some of whom had begun infringements upon the Watt patents, alarmed Messrs. Watt and Boulton so much that they decided Watt should apply for another patent, covering his important improvements since the first. Accordingly, October 25, 1781, the patent (already referred to on p. 91) was secured, "for certain new methods of producing a continued rotative motion around an axis or centre, and thereby to give motion to the wheels of mills or other machines."

This patent was necessary in consequence of the difficulties experienced in working the steam wheels or rotatory engines described in the first patent of 1769, and by Watt's having been so unfairly anticipated, by Wasborough in the crank motion.

No less than five different methods for rotatory motion are described in the patent, the fifth commonly known as the "sun and planet wheels," of which Watt writes to Boulton, January 3, 1782,

I have tried a model of one of my old plans of rotative engines, revived and executed by Mr. Murdoch, which merits being included in the specification as a fifth method; for which purpose I shall send a drawing and description next post. It has the singular property of going twice round for each stroke of the engine, and may be made to go oftener round, if required, without additional machinery.

Then followed an explanation of the sketch which he sent, and two days later he wrote, "I send you the drawings of the fifth method, and thought to have sent you the description complete, but it was late last night before I finished so far, and to-day have a headache, therefore only send you a rough draft of part."

In all of these Watt recommended that a fly-wheel be used to regulate the motion, but in the specification for the patent of the following year, 1782, his double-acting engine produced a more regular motion and rendered a fly-wheel unnecessary, "so that," he says, "in most of our great manufactories these engines now supply the place of water, wind and horse mills, and instead of carrying the work to the power, the prime agent is placed wherever it is most convenient to the manufacturer."

This marks one of the most important stages in the development of the steam engine. It was at last the portable machine it remains to-day, and was placed wherever convenient, complete in itself and with the rotative motion adaptable for all manner of work. The ingenious substitutes Watt had to invent to avoid the obviously perfect crank motion have of course all been discarded, and nothing of these remains except as proofs, where none are needed, that genius has powers in reserve for emergencies; balked in one direction, it hews out another path for itself.

While preparing the specification for this patent of 1781, Watt was busy upon another specification quite as important, which appeared in the following year, 1782. It embraced the following new improvements, the winnowing of numberless ideas and experiments that he had conceived and tested for some years previous:

1. The use of steam on the expansive principle; together with various methods or contrivances (six in number, some of them comprising various modifications), for equalising the expansive power.

2. The double-acting engine; in which steam is admitted to press the piston upward as well as downward; the piston being also aided in its ascent as well as in its descent by a vacuum produced by condensation on the other side.

3. The double-engine; consisting of two engines, primary and secondary, of which the steam-vessels and condensers communicate by pipes and valves, so that they can be worked either independently or in concert; and make their strokes either alternately or both together, as may be required.

4. The employment of a toothed rack and sector, instead of chains, for guiding the piston-rod.

5. A rotative engine, or steam-wheel.

Here we have three of the vital elements required toward the completion of the work: first, steam used expansively; second, the double-acting engine. It will be remembered that Watt's first engines only took in steam at the bottom of the cylinder, as Newcomen's did, but with this difference: Watt used the steam to perform work which Newcomen could not do, the latter only using steam to force the piston itself upward. Now came Watt's great step forward. Having a cylinder closed at the top, while the Newcomen cylinder remained open, it was as easy to admit steam at the top to press the piston down as to admit it at the bottom to press the piston up; also as easy to apply his condenser to the steam above as below, at the moment a vacuum was needed. All this was ingeniously provided for by numerous devices and covered by the patent. Third, he went one step farther to the compound engine, consisting of two engines, primary and secondary, working steam expansively independently or in concert, with strokes alternate or simultaneous. The compound engine was first thought of by Watt about 1767. He laid a large drawing of it on parchment before parliament when soliciting an extension of his first patent. The reason he did not proceed to construct it was "the difficulty he had encountered in teaching others the construction and use of the single engine, and in overcoming prejudices"; the patent of 1782 was only taken out because he found himself "beset with a host of plagiaries and pirates."

One of the earliest of these double-acting engines was erected at the Albion Mills, London, in 1786. Watt writes:

The mention of Albion Mills induces me to say a few words respecting an establishment so unjustly calumniated in its day, and the premature destruction of which, by fire, in 1791, was, not improbably, imputed to design. So far from being, as misrepresented, a monopoly injurious to the public, it was the means of considerably reducing the price of flour while it continued at work.

The "double-acting" engine was followed by the "compound" engine, of which Watt says:

A new compound engine, or method of connecting together the cylinders and condensers of two or more distinct engines, so as to make the steam which has been employed to press on the piston of the first, act expansively upon the piston of the second, etc., and thus derive an additional power to act either alternately or co-jointly with that of the first cylinder.

We have here, in all substantial respects, the modern engine of to-day.

Two fine improvements have been made since Watt's time: first, the piston-rings of Cartwright, which effectively removed one of Watt's most serious difficulties, the escape of steam, even though the best packing he could devise were used—the chief reason he could not use high-pressure steam. In our day, the use of this is rapidly extending, as is that of superheated steam. Packing the piston was an elaborate operation even after Watt's day.

It was not because Watt did not know as well as any of our present experts the advantages of high pressures, that he did not use them, but simply because of the mechanical difficulties then attending their adoption. He was always in advance of mechanical practicalities rather than behind, and as we have seen, had to retrace his steps, in the case of expansion.

The other improvement is the cross-head of Haswell, an American, a decided advance, giving the piston rod a smooth and straight bed to rest upon and freeing it from all disturbance. The drop valve is now displacing the slide valve as a better form of excluding or admitting steam.

Watt of course knew nothing of the thermo-dynamic value of high temperature without high pressure, altho fully conversant with the value of pressures. This had not been even imagined by either philosopher or engineer until discovered by Carnot as late as 1824. Even if he had known about it the mechanical arts in his day were in no condition to permit its use. Even high pressures were impracticable to any great extent. It is only during the past few years that turbines and superheating, having long been practically discarded, show encouraging signs of revival. They give great promise of advancement, the hitherto insuperable difficulties of lubrication and packing having been overcome within the last five years. Superheating especially promises to yield substantial results as compared with the practice with ordinary engines, but the margin of saving in steam over the best quadruple expansion engine cannot be great. Lord Kelvin however expects it to be the final contribution of science to the highest possible economy in the steam engine.

In the January (1905) number of "Stevens Institute Indicator," Professor Denton has an instructive rÉsumÉ of recent steam engine economics. He tells us that Steam Turbines are now being applied to Piston Engines to operate with the latter's exhaust, to effect the same saving as the sulphur dioxide cylinder; and adds

that the Turbine is a formidable competitor to the Piston Engine is mainly due to the fact that it more completely realizes the expansive principle enunciated in the infancy of steam history as the fundamental factor of economy by its sagacious founder, the immortal Watt.

Watt's favorite employment in Soho works late in 1783 and early in 1784 was to teach his engine, now become as docile as it was powerful, to work a tilt hammer. In 1777 he had written Boulton that

Wilkinson wants an engine to raise a stamp of 15 cwt. thirty or forty times in a minute. I have set Webb to work to try it with the little engine and a stamp-hammer of 60 lbs. weight. Many of these battering rams will be wanted if they answer.

The trial was successful. A new machine to work a 700 lbs. hammer for Wilkinson was made, and April 27, 1783, Watt writes that

it makes from 15 to 50, and even 60, strokes per minute, and works a hammer, raised two feet high, which has struck 300 blows per minute.

The engine was to work two hammers, but was capable of working four of 7 cwt. each. He says, with excusable pride,

I believe it is a thing never done before, to make a hammer of that weight make 300 blows per minute; and, in fact, it is more a matter to brag of than for any other use, as the rate wanted is from 90 to 100 blows, being as quick as the workmen can manage the iron under it.

This most ingenious application of steam power was included in Watt's next patent of April 28, 1784. It embraced many improvements, mostly, however, now of little consequence, the most celebrated being "parallel motion," of which Watt was prouder than any other of his triumphs. He writes to his son, November, 1808, twenty-four years after it was invented (1784):

Though I am not over anxious after fame, yet I am more proud of the parallel motion than of any other mechanical invention I have ever made.

He wrote Boulton, in June, 1784:

I have started a new hare. I have got a glimpse of a method of causing a piston-rod to move up and down perpendicularly, by only fixing it to a piece of iron upon the beam ... I think it one of the most ingenious simple pieces of mechanism I have contrived.

October, 1784, he writes:

The new central perpendicular motion answers beyond expectation, and does not make the shadow of a noise.

He says:

When I saw it in movement, it afforded me all the pleasure of a novelty, as if I had been examining the invention of another.

When beam-engines were universally used for pumping, this parallel motion was of great advantage. It has been superseded in our day, by improved piston guides and cross-heads, the construction of which in Watt's day was impossible, but no invention has commanded in greater degree the admiration of all who comprehend the principles upon which it acts, or who have witnessed the smoothness, orderly power and "sweet simplicity" of its movements. Watt's pride in it as his favorite invention in these respects is fully justified.

A detailed specification for a road steam-carriage concludes the claims of this patent, but the idea of railroads, instead of common roads, coming later left the construction of the locomotive to Stephenson.[1]

Watt's last patent bears date June 14, 1785, and was

for certain newly improved methods of constructing furnaces or fire-places for heating, boiling, or evaporating of water and other liquids which are applicable to steam engines and other purposes, and also for heating, melting, and smelting of metals and their ores, whereby greater effects are produced from the fuel, and the smoke is in a great measure prevented or consumed.

The principle, "an old one of my own," as Watt says, is in great part acted upon to-day.

So numerous were the improvements made by Watt at various periods, which greatly increased the utility of his engine, it would be in vain to attempt a detailed recital of his endless contrivances, but we may mention as highly important, the throttle-valve, the governor, the steam-gauge and the indicator. Muirhead says:

The throttle-valve is worked directly by the engineer to start or stop the engine, and also to regulate the supply of steam. Watt describes it as a circular plate of metal, having a spindle fixed across its diameter, the plate being accurately fitted to an aperture in a metal ring of some thickness, through the edgeway of which the spindle is fitted steam-tight, and the ring fixed between the two flanches of the joint of the steam-pipe which is next to the cylinder. One end of the spindle, which has a square upon it, comes through the ring, and has a spanner fixed upon it, by which it can be turned in either direction. When the valve is parallel to the outsides of the ring, it shuts the opening nearly perfectly; but when its plane lies at an angle to the ring, it admits more or less steam according to the degree it has opened; consequently the piston is acted upon with more or less force.

Papin preferred gunpowder as a safer source of power than steam, but that was before it had been automatically regulated by the "Governor." The governor has always been the writer's favorite invention, probably because it was the first he fully understood. It is an application of the centrifugal principle adapted and mechanically improved. Two heavy revolving balls swing round an upright rod. The faster the rod revolves the farther from it the balls swing out. The slower it turns the closer the balls fall toward it. By proper attachments the valve openings admitting steam are widened or narrowed accordingly. Thus the higher speed of the engine, the less steam admitted, the slower the speed the more steam admitted. Hence any uniform speed desired can be maintained: should the engine be called upon to perform greater service at one moment than another, as in the case of steel rolling mills, speed being checked when the piece of steel enters the rolls, immediately the valves widen, more steam rushes into the engine, and vice versa. Until the governor came regular motion was impossible—steam was an unruly steed.

Arago describes the steam-gauge thus:

It is a short glass tube with its lower end immersed in a cistern of mercury, which is placed within an iron box screwed to the boiler steam-pipe, or to some other part communicating freely with the steam, which, pressing on the surface of the mercury in the cistern, raises the mercury in the tube (which is open to the air at the upper end), and its altitude serves to show the elastic power of the steam over that of the atmosphere.

The indicator he thus describes:

The barometer being adapted only to ascertain the degree of exhaustion in the condenser where its variations were small, the vibrations of the mercury rendered it very difficult, if not impracticable, to ascertain the state of the exhaustion of the cylinder at the different periods of the stroke of the engine; it became therefore necessary to contrive an instrument for that purpose that should be less subject to vibration, and should show nearly the degree of exhaustion in the cylinder at all periods. The following instrument, called the Indicator, is found to answer the end sufficiently. A cylinder about an inch diameter, and six inches long, exceedingly truly bored, has a solid piston accurately fitted to it, so as to slide easy by the help of some oil; the stem of the piston is guided in the direction of the axis of the cylinder, so that it may not be subject to jam, or cause friction in any part of its motion. The bottom of this cylinder has a cock and small pipe joined to it which, having a conical end, may be inserted in a hole drilled in the cylinder of the engine near one of the ends, so that, by opening the small cock, a communication may be effected between the inside of the cylinder and the indicator.

The cylinder of the indicator is fastened upon a wooden or metal frame, more than twice its own length; one end of a spiral steel spring, like that of a spring steel-yard, is attached to the upper part of the frame, and the other end of the spring is attached to the upper end of the piston-rod of the indicator. The spring is made of such a strength, that when the cylinder of the indicator is perfectly exhausted, the pressure of the atmosphere may force its piston down within an inch of its bottom. An index being fixed to the top of its piston-rod, the point where it stands, when quite exhausted, is marked from an observation of a barometer communicating with the same exhausted vessel, and the scale divided accordingly.

Improvements come in many ways, sometimes after much thought and after many experimental failures. Sometimes they flash upon clever inventors, but let us remember this is only after they have spent long years studying the problem. In the case of the steam engine, however, a quite important improvement came very curiously. Humphrey Potter was a lad employed to turn off and on the stop cocks of a Newcomen engine, a monotonous task, for, at every stroke one had to be turned to let steam into the boiler and another for injecting the cold water to condense it, and this had to be done at the right instant or the engine could not move. How to relieve himself from the drudgery became the question. He wished time to play with the other boys whose merriment was often heard at no great distance, and this set him thinking. Humphrey saw that the beam in its movements might serve to open and shut these stop cocks and he promptly began to attach cords to the cocks and then tied them at the proper points to the beam, so that ascending it pulled one cord and descending the other. Thus came to us perhaps not the first automatic device, but no doubt the first of its kind that was ever seen there. The steam engine henceforth was self-attending, providing itself for its own supply of steam and for its condensation with perfect regularity. It had become in this feature automatic.

The cords of Potter gave place to vertical rods with small pegs which pressed upward or downward as desired. These have long since been replaced by other devices, but all are only simple modifications of a contrivance devised by the mere lad whose duty it was to turn the stop cocks.

It would be interesting to know the kind of man this precocious boy inventor became, or whether he received suitable reward for his important improvement. We search in vain; no mention of him is to be found. Let us, however, do our best to repair the neglect and record that, in the history of the steam engine, Humphrey Potter must ever be honorably associated with famous men as the only famous boy inventor.

In the development of the steam engine, we have one purely accidental discovery. In the early Newcomen engines, the head of the piston was covered by a sheet of water to fill the spaces between the circular contour of the movable piston and the internal surface of the cylinder, for there were no cylinder-boring tools in those days, and surfaces of cylinders were most irregular. To the surprise of the engineer, the engine began one day working at greatly increased speed, when it was found that the piston-head had been pierced by accident and that the cold water had passed in small drops into the cylinder and had condensed the steam, thus rapidly making a more perfect vacuum. From this accidental discovery came the improved plan of injecting a shower of cold water through the cylinder, the strokes of the engine being thus greatly increased.

The year 1783 was one of Watt's most fruitful years of the dozen which may be said to have teemed with his inventions. His celebrated discovery of the composition of water was published in this year. The attempts made to deprive him of the honor of making this discovery ended in complete failure. Sir Humphrey Davy, Henry, Arago, Liebig, and many others of the highest authority acknowledged and established Watt's claims.

The true greatness of the modest Watt was never more finely revealed than in his correspondence and papers published during the controversy. Watt wrote Dr. Black, April 21st, that he had handed his paper to Dr. Priestley to be read at the Royal Society. It contained the new idea of water, hitherto considered an element and now discovered to be a compound. Thus was announced one of the most wonderful discoveries found in the history of science. It was justly termed the beginning of a new era, the dawn of a new day in physical chemistry, indeed the real foundation for the new system of chemistry, and, according to Dr. Young, "a discovery perhaps of greater importance than any single fact which human ingenuity has ascertained either before or since." What Newton had done for light Watt was held to have done for water. Muirfield well says:

It is interesting in a high degree to remark that for him who had so fully subdued to the use of man the gigantic power of steam it was also reserved to unfold its compound natural and elemental principles, as if on this subject there were to be nothing which his researches did not touch, nothing which they touched that they did not adorn.

Arago says:

In his memoir of the month of April, Priestley added an important circumstance to those resulting from the experiments of his predecessors: he proved that the weight of the water which is deposited upon the sides of the vessel, at the instant of the detonation of the oxygen and hydrogen, is precisely the same as the weights of the two gases.

Watt, to whom Priestley communicated this important result, immediately perceived that proof was here afforded that water was not a simple body. Writing to his illustrious friend, he asks:

What are the products of your experiment? They are water, light and heat. Are we not, thence, authorised to conclude that water is a compound of the two gases, oxygen and hydrogen, deprived of a portion of their latent or elementary heat; that oxygen is water deprived of its hydrogen, but still united to its latent heat and light? If light be only a modification of heat, or a simple circumstance of its manifestation, or a component part of hydrogen, oxygen gas will be water deprived of its hydrogen, but combined with latent heat.

This passage, so clear, so precise, and logical, is taken from a letter of Watt's, dated April 26, 1783. The letter was communicated by Priestley to several of the scientific men in London, and was transmitted immediately afterward to Sir Joseph Banks, the President of the Royal Society, to be read at one of the meetings of that learned body.

Watt had for many years entertained the opinion that air was a modification of water. He writes Boulton, December 10, 1782:

You may remember that I have often said, that if water could be heated red-hot or something more, it would probably be converted into some kind of air, because steam would in that case have lost all its latent heat, and that it would have been turned solely into sensible heat, and probably a total change of the nature of the fluid would ensue.

A month after he hears of Priestley's experiments, he writes Dr. Black (April 21, 1783) that he "believes he has found out the cause of the conversion of water into air." A few days later, he writes to Dr. Priestley:

In the deflagration of the inflammable and dephlogisticated airs, the airs unite with violence—become red-hot—and, on cooling, totally disappear. The only fixed matter which remains is water; and water, light, and heat, are all the products. Are we not then authorised to conclude that water is composed of dephlogisticated and inflammable air, or phlogiston, deprived of part of their latent heat; and that dephlogisticated, or pure air, is composed of water deprived of its phlogiston, and united to heat and light; and if light be only a modification of heat, or a component part of phlogiston, then pure air consists of water deprived of its phlogiston and of latent heat?

It appears from the letter to Dr. Black of April 21st, that Mr. Watt had, on that day, written his letter to Dr. Priestley, to be read by him to the Royal Society, but on the 26th he informs Mr. DeLuc, that having observed some inaccuracies of style in that letter, he had removed them, and would send the Doctor a corrected copy in a day or two, which he accordingly did on the 28th; the corrected letter (the same that was afterward embodied verbatim in the letter to Mr. DeLuc, printed in the Philosophical Transactions), being dated April 26th. In enclosing it, Mr. Watt adds, "As to myself, the more I consider what I have said, I am the more satisfied with it, as I find none of the facts repugnant."

Thus was announced for the first time one of the most wonderful discoveries recorded in the history of science, startling in its novelty and yet so simple.

Watt had divined the import of Priestley's experiment, for he had mastered all knowledge bearing upon the question, but even when this was communicated to Priestley, he could not accept it, and, after making new experiments, he writes Watt, April 29, 1783, "Behold with surprise and indignation the figure of an apparatus that has utterly ruined your beautiful hypothesis," giving a rough sketch with his pen of the apparatus employed. Mark the promptitude of the master who had deciphered the message which the experimenter himself could not translate. He immediately writes in reply May 2, 1783:

I deny that your experiment ruins my hypothesis. It is not founded on so brittle a basis as an earthen retort, nor on its converting water into air. I founded it on the other facts, and was obliged to stretch it a good deal before it would fit this experiment.... I maintain my hypothesis until it shall be shown that the water formed after the explosion of the pure and inflammable airs, has some other origin.

He also writes to Mr. DeLuc on May 18th:

I do not see Dr. Priestley's experiment in the same light that he does. It does not disprove my theory.... My assertion was simply, that air (i.e., dephlogisticated air, or oxygen, which was also commonly called vital air, pure air, or simple air) was water deprived of its phlogiston, and united to heat, which I grounded on the decomposition of air by inflammation with inflammable air, the residuum, or product of which, is only water and heat.

Having, by experiments of his own, fully satisfied himself of the correctness of his theory, in November he prepared a full statement for the Royal Society, having asked the society to withhold his first paper until he could prove it for himself by experiment. He never doubted its correctness, but some members of the society advised that it had better be supported by facts.

When the discovery was so daring that Priestley, who made the experiments, could not believe it and had to be convinced by Watt of its correctness, there seems little room left for other claimants, nor for doubt as to whom is due the credit of the revelation.

Watt encountered the difficulties of different weights and measures in his studies of foreign writers upon chemistry, a serious inconvenience which still remains with us.

He wrote Mr. Kirwan, November, 1783:

I had a great deal of trouble in reducing the weights and measures to speak the same language; and many of the German experiments become still more difficult from their using different weights and different divisions of them in different parts of that empire. It is therefore a very desirable thing to have these difficulties removed, and to get all philosophers to use pounds divided in the same manner, and I flatter myself that may be accomplished if you, Dr. Priestley, and a few of the French experimenters will agree to it; for the utility is so evident, that every thinking person must immediately be convinced of it.

Here follows his plan: Let the

Philosophical pound consist of 10 ounces, or 10,000 grains.
the ounce " " 10 drachms or 1,000 "
the drachm " " 100 grains.

Let all elastic fluids be measured by the ounce measure of water, by which the valuation of different cubic inches will be avoided, and the common decimal tables of specific gravities will immediately give the weights of those elastic fluids.

If all philosophers cannot agree on one pound or one grain, let every one take his own pound or his own grain; it will affect nothing but doses of medicines, which must be corrected as is now done; but as it would be much better that the identical pound was used by all. I would propose that the Amsterdam or Paris pound be assumed as the standard, being now the most universal in Europe: it is to our avoirdupois pound as 109 is to 100. Our avoirdupois pound contains 7,000 of our grains, and the Paris pound 7,630 of our grains, but it contains 9,376 Paris grains, so that the division into 10,000 would very little affect the Paris grain. I prefer dividing the pound afresh to beginning with the Paris grain, because I believe the pound is very general, but the grain local.

Dr. Priestley has agreed to this proposal, and has referred it to you to fix upon the pound if you otherwise approve of it. I shall be happy to have your opinion of it as soon as convenient, and to concert with you the means of making it universal.... I have some hopes that the foot may be fixed by the pendulum and a measure of water, and a pound derived from that; but in the interim let us at least assume a proper division, which from the nature of it must be intelligible as long as decimal arithmetic is used.

He afterward wrote, in a letter to Magellan:

As to the precise foot or pound, I do not look upon it to be very material, in chemistry at least. Either the common English foot may be adopted according to your proposal, which has the advantage that a cubic foot is exactly 1,000 ounces, consequently the present foot and ounce would be retained; or a pendulum which vibrates 100 times a minute may be adopted for the standard, which would make the foot 14.2 of our present inches, and the cubic foot would be very exactly a bushel, and would weigh 101 of the present pounds, so that the present pound would not be much altered. But I think that by this scheme the foot would be too large, and that the inconvenience of changing all the foot measures and things depending on them, would be much greater than changing all the pounds, bushels, gallons, etc. I therefore give the preference to those plans which retain the foot and ounce.

The war of the standards still rages—metric, or decimal, or no change. What each nation has is good enough for it in the opinion of many of its people. Some day an international commission will doubtless assemble to bring order out of chaos. As far as the English-speaking race is concerned, it seems that a decided improvement could readily be affected with very trifling, indeed scarcely perceptible, changes. Especially is this so with money values. Britain could merge her system with those of Canada and America, by simply making her "pound" the exact value of the American five dollars, it being now only ten pence less; her silver coinage one and two shillings equal to quarter- and half-dollars, the present coin to be recoined upon presentation, but meanwhile to pass current. Weights and measures are more difficult to assimilate. Science being world-wide, and knowing no divisions, should use uniform terms. Alas! at the distance of nearly a century and a half we seem no nearer the prospect of a system of universal weights and measures than in Watt's day, but Watt's idea is not to be lost sight of for all that. He was a seer who often saw what was to come.

We have referred to the absence of holidays in Watt's strenuous life, but Birmingham was remarkable for a number of choice spirits who formed the celebrated Lunar Society, whose members were all devoted to the pursuit of knowledge and mutually agreeable to one another. Besides Watt and Boulton, there were Dr. Priestley, discoverer of oxygen gas, Dr. Darwin, Dr. Withering, Mr. Keir, Mr. Galton, Mr. Wedgwood of Wedgwood ware fame, who had monthly dinners at their respective houses—hence the "Lunar" Society. Dr. Priestley, discoverer of oxygen, who arrived in Birmingham in 1780, has repeatedly mentioned the great pleasure he had in having Watt for a neighbor. He says:

I consider my settlement at Birmingham as the happiest event in my life; being highly favourable to every object I had in view, philosophical or theological. In the former respect I had the convenience of good workmen of every kind, and the society of persons eminent for their knowledge of chemistry; particularly Mr. Watt, Mr. Keir, and Dr. Withering. These, with Mr. Boulton and Dr. Darwin, who soon left us by removing from Lichfield to Derby, Mr. Galton, and afterwards Mr. Johnson of Kenilworth and myself, dined together every month, calling ourselves the Lunar Society, because the time of our meeting was near the full-moon—in order,

as he elsewhere says,

to have the benefit of its light in returning home.

Richard Lovell Edgeworth says of this distinguished coterie:

By means of Mr. Keir, I became acquainted with Dr. Small of Birmingham, a man esteemed by all who knew him, and by all who were admitted to his friendship beloved with no common enthusiasm. Dr. Small formed a link which combined Mr. Boulton, Mr. Watt, Dr. Darwin, Mr. Wedgwood, Mr. Day, and myself together—men of very different characters, but all devoted to literature and science. This mutual intimacy has never been broken but by death, nor have any of the number failed to distinguish themselves in science or literature. Some may think that I ought with due modesty to except myself. Mr. Keir, with his knowledge of the world and good sense; Dr. Small, with his benevolence and profound sagacity; Wedgwood, with his increasing industry, experimental variety, and calm investigation; Boulton, with his mobility, quick perception, and bold adventure; Watt, with his strong inventive faculty, undeviating steadiness, and bold resources; Darwin, with his imagination, science, and poetical excellence; and Day with his unwearied research after truth, his integrity and eloquence proved altogether such a society as few men have had the good fortune to live with; such an assemblage of friends, as fewer still have had the happiness to possess, and keep through life.

The society continued to exist until the beginning of the century, 1800. Watt was the last surviving member. The last reference is Dr. Priestley's dedication to it, in 1793, of one of his works "Experiments on the Generation of Air from Water," in which he says:

There are few things that I more regret, in consequence of my removal from Birmingham, than the loss of your society. It both encouraged and enlightened me; so that what I did there of a philosophical kind ought in justice to be attributed almost as much to you as to myself. From our cheerful meetings I never absented myself voluntarily, and from my pleasing recollection they will never be absent. Should the cause of our separation make it necessary for to me remove to a still greater distance from you, I shall only think the more, and with the more regret, of our past interviews.... Philosophy engrossed us wholly. Politicians may think there are no objects of any consequence besides those which immediately interest them. But objects far superior to any of which they have an idea engaged our attention, and the discussion of them was accompanied with a satisfaction to which they are strangers. Happy would it be for the world if their pursuits were as tranquil, and their projects as innocent, and as friendly to the best interests of mankind, as ours.

That the partners, Boulton and Watt, had such pleasure amid their lives of daily cares, all will be glad to know. It was not all humdrum money-making nor intense inventing. There was the society of gifted minds, the serene atmosphere of friendship in the high realms of mutual regard, best recreation of all.

In 1786, quite a break in their daily routine took place. In that year Messrs. Boulton and Watt visited Paris to meet proposals for their erecting steam engines in France under an exclusive privilege. They were also to suggest improvements on the great hydraulic machine of Marly. Before starting, the sagacious and patriotic Watt wrote to Boulton:

I think if either of us go to France, we should first wait upon Mr. Pitt (prime minister), and let him know our errand thither, that the tongue of slander may be silenced, all undue suspicion removed, and ourselves rendered more valuable in his eyes, because others desire to have us!

They had a flattering reception in Paris from the ministry, who seemed desirous that they should establish engine-works in France. This they absolutely refused to do, as being contrary to the interests of their country. It may be feared we are not quite so scrupulous in our day. On the other hand, refusal now would be fruitless, it has become so easy to obtain plans, and even experts, to build machines for any kind of product in any country. Automatic machinery has almost dispelled the need for so-called skilled labor. East Indians, Mexicans, Japanese, Chinese, all become more or less efficient workers with a few month's experience. Manufacturing is therefore to spread rapidly throughout the world. All nations may be trusted to develop, and if necessary for a time protect, their natural resources as a patriotic duty. Only when prolonged trials have been made can it be determined which nation can best and most cheaply provide the articles for which raw material abounds.

The visit to Paris enabled Watt and Boulton to make the acquaintance of the most eminent men of science, with whom they exchanged ideas afterward in frequent and friendly correspondence. Watt described himself as being, upon one occasion, "drunk from morning to night with Burgundy and undeserved praise." The latter was always a disconcerting draught for our subject; anything but reference to his achievements for the modest self-effacing genius.

While in Paris, Berthollet told Watt of his new method of bleaching by chlorine, and gave him permission to communicate it to his father-in-law, who adopted it in his business, together with several improvements of Watt's invention, the results of a long series of experiments. Watt, writing to Mr. Macgregor, April 27, 1787, says:

In relation to the inventor, he is a man of science, a member of the Academy of Sciences at Paris, and a physician, not very rich, a very modest and worthy man, and an excellent chemist. My sole motives in meddling with it were to procure such reward as I could to a man of merit who had made an extensively useful discovery in the arts, and secondly, I had an immediate view to your interest; as to myself, I had no lucrative views whatsoever, it being a thing out of my way, which both my business and my health prevented me from pursuing further than it might serve for amusement when unfit for more serious business. Lately, by a letter from the inventor, he informs me that he gives up all intentions of pursuing it with lucrative views, as he says he will not compromise his quiet and happiness by engaging in business; in which, perhaps, he is right; but if the discovery has real merit, as I apprehend, he is certainly entitled to a generous reward, which I would wish for the honour of Britain, to procure for him; but I much fear, in the way you state it, that nothing could be got worth his acceptance.

France has been distinguished for men of science who have thus refrained from profiting by their inventions. Pasteur, in our day, perhaps the most famous of all, the liver, not only of the simple but of the ideal life, laboring for the good of humanity—service to man—and taking for himself the simple life, free from luxury, palace, estate, and all the inevitable cares accompanying ostentatious living. Berthollet preceded him. Like Agassiz, these gifted souls were "too busy to make money."

In 1792, when Boulton had passed the allotted three score years and ten, and Watt was over three score, they made a momentous decision which brought upon them several years of deep anxiety. Fortunately the sons of the veterans who had recently been admitted to the business proved of great service in managing the affair, and relieved their parents of much labor and many journeys. Fortunate indeed were Watt and Boulton in their partnership, for they became friends first and partners afterward. They were not less fortunate in each having a talented son, who also became friends and partners like their fathers before them. The decision was that the infringers of their patents were to be proceeded against. They had to appeal to the law to protect their rights.

Watt met the apparently inevitable fate of inventors. Rivals arose in various quarters to dispute his right to rank as the originator of many improvements. No reflection need be made upon most rival claimants to inventions. Some wonderful result is conceived to be within the range of possibility, which, being obtained, will revolutionise existing modes. A score of inventive minds are studying the problem throughout the civilised world. Every day or two some new idea flashes upon one of them and vanishes, or is discarded after trial. One day the announcement comes of triumphant success with the very same idea slightly modified, the modification or addition, slight though this may be, making all the difference between failure and success. The man has arrived with the key that opens the door of the treasure-house. He sets the egg on end perhaps by as obvious a plan as chipping the end. There arises a chorus of strenuous claimants, each of whom had thought of that very device long ago. No doubt they did. They are honest in their protests and quite persuaded in their own minds that they, and not the Watt of the occasion, are entitled to the honor of original discovery. This very morning we read in the press a letter from the son of Morse, vindicating his father's right to rank as the father of the telegraph, a son of Vail, one of his collaborators, having claimed that his father, and not Morse, was the real inventor. The most august of all bodies of men, since its decisions overrule both Congress and President, the Supreme Court of the United States, has shown rare wisdom from its inception, and in no department more clearly than in that regarding the rights of inventors. No court has had such experience with patent claims, for no nation has a tithe of the number to deal with. Throughout its history, the court has attached more and more importance to two points: First, is the invention valuable? Second, who proved this in actual practice? These points largely govern its decisions.

The law expenses of their suits seemed to Boulton and Watt exorbitant, even in that age of low prices compared to our own. One solicitors bill was for no less than $30,000, which caused Watt years afterward, when speaking of an enormous charge to say that "it would not have disgraced a London solicitor." When we find however, that this was for four years' services, the London solicitor appears in a different light. "In the whole affair," writes Watt to his friend Dr. Black, January 15, 1797, "nothing was so grateful to me as the zeal of our friends and the activity of our young men, which were unremitting."

The first trial ended June 22, 1793, with a verdict for Watt and Boulton by the jury, subject to the opinion of the court as to the validity of the patent. On May 16, 1795, the case came on for judgment, when unfortunately the court was found divided, two for the patent and two against. Another case was tried December 16, 1796, with a special jury, before Lord Chief Justice Eyre; the verdict was again for the plaintiffs. Proceedings on a writ of error had the effect of affirming the result by the unanimous opinion of the four judges, before whom it was ably and fully argued on two occasions.

The testimony of Professor Robison, Watt's intimate friend of youth in Glasgow, was understood to have been deeply impressive, and to have had a decisive effect upon judges and jury.

All the claims of Watt were thus triumphantly sustained. The decision has always been considered of commanding importance to the law of patents in Britain, and was of vast consequence to the firm of Watt and Boulton pecuniarily. Heavy damages and costs were due from the actual defendants, and the large number of other infringers were also liable for damages. As was to have been expected, however, the firm remembered that to be merciful in the hour of victory and not to punish too hard a fallen foe, was a cardinal virtue. The settlements they made were considered most liberal and satisfactory to all. Watt used frequently long afterward to refer to his specifications as his old and well-tried friends. So indeed they proved, and many references to their wonderful efficiency were made.

With the beginning of the new century, 1800, the original partnership of the famous firm of Boulton and Watt expired, after a term of twenty-five years, as did the patents of 1769 and 1775. The term of partnership had been fixed with reference to the duration of the patents. Young men in their prime, Watt at forty and Boulton about fifty when they joined hands, after a quarter-century of unceasing and anxious labor, were disposed to resign the cares and troubles of business to their sons. The partnership therefore was not renewed by them, but their respective shares in the firm were agreed upon as the basis of a new partnership between their sons, James Watt, Jr., Matthew Robinson Boulton and Gregory Watt, all distinguished for abilities of no mean order, and in a great degree already conversant with the business, which their wise fathers had seen fit for some years to entrust more and more to them.

In nothing done by either of these two wise fathers is more wisdom shown than in their sagacious, farseeing policy in regard to their sons. As they themselves had been taught to concentrate their energies upon useful occupation, for which society would pay as for value received, they had doubtless often conferred, and concluded that was the happiest and best life for their sons, instead of allowing them to fritter away the precious years of youth in aimless frivolity, to be followed in later years by a disappointing and humiliating old age.

So the partnership of Boulton and Watt was renewed in the union of the sons. Gregory Watt's premature death four years later was such a blow to his father that some think he never was quite himself again. Gregory had displayed brilliant talents in the higher pursuits of science and literature, in which he took delight, and great things had been predicted from him. With the other two sons the business connection continued without change for forty years, until, when old men, they also retired like their fathers. They proved to be great managers, for notwithstanding the cessation of the patents which opened engine-building free to all, the business of the firm increased and became much more profitable than it had ever been before; indeed toward the close of the original partnership, and upon the triumph gained in the patent suits, the enterprise became so profitable as fully to satisfy the moderate desire of Watt, and to provide a sure source of income for his sons. This met all his wishes and removed the fears of becoming dependent that had so long haunted him.

The continued and increasing success of the Soho works was obviously owing to the new partners. They had some excellent assistants, but in the foremost place among all of them stands Murdoch, Watt's able, faithful and esteemed assistant for many years, who, both intellectually and in manly independence, was considered to exhibit no small resemblance to his revered master and friend. Never formally a partner in Soho (for he declined partnership as we have seen), he was placed on the footing of a partner by the sons in 1810, without risk, and received $5,000 per annum. From 1830 he lived in peaceful retirement and passed away in 1839. His remains were deposited in Handsworth Church near those of his friends and employers, Watt and Boulton (the one spot on earth he could have most desired). "A bust by Chantrey serves to perpetuate the remembrance of his manly and intelligent features, and of the mind of which these were a pleasing index." We may imagine the shades of Watt and Boulton, those friends so appropriately laid together, greeting their friend and employee: "Well done, thou good and faithful servant!" If ever there was one, Murdoch was the man, and Captain Jones his fellow.

We have referred to Watt's suggestion of the screw-propeller, and of the sketch of it sent to Dr. Small, September 30, 1770. The only record of any earlier suggestion of steam is that of Jonathan Hulls, in 1736, and which he set forth in a pamphlet entitled "A Description and Draught of a Newly Invented Machine for carrying vessels or ships out of or into any Harbour, Port or River, against Wind or Tide or in a Calm"; London, 1737. He described a large barge equipped with a Newcomen engine to be employed as a tug, fitted with fan (or paddle) wheels, towing a ship of war, but nothing further appears to have been done. Writing on this subject, Mr. Williamson says:

During his last visit to Greenock in 1816, Mr. Watt, in company with his friend, Mr. Walkinshaw—whom the author some years afterward heard relate the circumstance—made a voyage in a steamboat as far as Rothsay and back to Greenock—an excursion, which, in those days, occupied a greater portion of a whole day. Mr. Watt entered into conversation with the engineer of the boat, pointing out to him the method of "backing" the engine. With a footrule he demonstrated to him what was meant. Not succeeding, however, he at last, under the impulse of the ruling passion, threw off his overcoat, and, putting his hand to the engine himself, showed the practical application of his lecture. Previously to this, the "back-stroke" of the steamboat engine was either unknown, or not generally known. The practice was to stop the engine entirely a considerable time before the vessel reached the point of mooring, in order to allow for the gradual and natural diminution of her speed.

The naval review at Spithead, upon the close of the Crimean war in 1856, was the greatest up to that time. Ten vessels out of two hundred and fifty still had not steam power, but almost all the others were propelled by the screw—the spiral oar of Watt's letter of 1770—a red-letter day for the inventor.

Watt's early interest in locomotive steam-carriages, dating from Robison's having thrown out the idea to him, was never lost. On August 12, 1768, Dr. Small writes Watt, referring to the "peculiar improvements in them" the latter had made previous to that date. Seven months later he apprises Watt that "a patent for moving wheel-carriages by steam has been taken out by one Moore," adding "this comes of thy delays; do come to England with all possible speed." Watt replied "If linen-draper Moore does not use my engine to drive his chaises he can't drive them by steam." Here Watt hit the nail on the head; as with the steamship, so with the locomotive, his steam-engine was the indispensable power. In 1786 he states that he has a carriage model of some size in hand "and am resolved to try if God will work a miracle in favor of these carriages." Watt's doubt was based on the fact that they would take twenty pounds of coal and two cubic feet of water per horse-power on the common roads.

Another of Watt's recreations in his days of semi-retirement was the improvement of lamps. He wrote the famous inventor of the Argand burner fully upon the subject in August, 1787, and constructed some lamps which proved great successes.

The following year he invented an instrument for determining the specific gravities of liquids, which was generally adopted.

One of Watt's inventions was a new method of readily measuring distances by telescope, which he used in making his various surveys for canals. Such instruments are in general use to-day. Brough's treatise on "Mining" (10th ed., p. 228) gives a very complete account of them, and states that "the original instrument of this class is that invented by James Watt in 1771."

In his leisure hours, Watt invented an ingenious machine for drawing in perspective, using the double parallel ruler, then very little known and not at all used as far as Watt knew. Watt reports having made from fifty to eighty of these machines, which went to various parts of the world.

In 1810 Watt informs Berthollet that for several years he had felt unable, owing to the state of his health, to make chemical experiments. But idle he could not be; he must be at work upon something. As he often said, "without a hobby-horse, what is life?" So the saying is reported, but we may conclude that the "horse" is here an interpolation, for the difference between "a horse" and "a hobby" is radical—a man can get off a horse.

Watt's next "hobby" fortunately became an engrossing occupation and kept him alert. This was a machine for copying sculpture. A machine he had seen in Paris for tracing and multiplying the dies of medals, suggested the other. After much labor and many experiments he did get some measure of success, and made a large head of Locke in yellow wood, and a small head of his friend Adam Smith.

Long did Watt toil at the new hobby in the garret where it had been created, but the garret proved too hot in summer and too cold in winter. March 14, 1810, he writes Berthollet and LevÈque:

I still do a little in mechanics: a part of which, if I live to complete it, I shall have the honor of communicating to my friends in France.

He went steadily forward and succeeded in making some fine copies in 1814. For one of Sappho he gives dates and the hours required for various parts, making a total of thirty-nine. Some censorious Sabbatarians discovered that the day he was employed one hour "doing her breast with 1/8th drill" was Sabbath, which in one who belonged to a strict Scottish Covenanter family, betokened a sad fall from grace. When we consider that his health was then precarious, that he was debarred from chemical experiments, and depended solely upon mechanical subjects; that in all probability it was a stormy day (Sunday, February 3, 1811), knowing also that "Satan finds mischief still for idle hands to do," we hope our readers will pardon him for yielding to the irresistible temptation, even if on the holy Sabbath day for once he could not "get off" his captivating hobby.

The historical last workshop of the great worker with all its contents remains open to the public to-day just as it was when he passed away. Pilgrims from many lands visit it, as Shakespeare's birthplace, Burns' cottage, and Scott's Abbottsford attract their many thousands yearly. We recommend our readers to add to these this garret of Watt in their pilgrimages.

[1] Sinclair's "Development of the Locomotive" tends to deprive Stephenson of some part of his fame as inventor. Much importance is attached to Hedley's "Puffing Billy," 1813, which is pronounced to have been a commercial success. Sinclair, however, credits Stephenson with doing most of all men to introduce the Locomotive. As the final verdict may admit Hedley and cannot expel Stephenson from the temple of fame, we pass the sentence as written, leaving to future disputants to adjust rival claims.