Chapter 7

The following may be taken as a brief summary of Professor Riedler's conclusions: Recent improvements in central station practice have resulted in an increased efficiency of about 30 per cent. in the compressors, but this benefit can only be realized when the new station is in operation. That the small and very imperfect air engines in use on the system give an efficiency of 50 per cent., while with ordinary steam engines driven by air an efficiency of 80 per cent. can be reached with a very small expenditure of fuel for heating the air before admitting it into the motor. That special attention should be given to the improvement of air engines, and that with increased initial pressures at the central station the distance of the transmission can be very considerably augmented. Finally, Professor Riedler claims that power can be transmitted by compressed air more conveniently and more economically than by any other means.

* * * * *

[Continued from SUPPLEMENT, No. 802, page 12810.]

THE BUILDERS OF THE STEAM ENGINE--THE FOUNDERS OF MODERN INDUSTRIES AND NATIONS.[1]

[Footnote 1: An address delivered at the Centennial Celebration of the American Patent System, Washington, April, 1891.]

By Dr. R.H. THURSTON, Director of Sibley College, Cornell University.

Papin, Worcester, Savery, were the authors of the period of application of the power of steam to useful work in our later days. The world was, in their time, just waking into a new life under the stimulus of a new freedom that, from the time of Shakespeare, of Newton, and of Gilbert, the physicist, has steadily become wider, higher, and more fruitful year by year. All the modern sciences and all the modern arts had their reawakening with the seventeenth century. Every aspect of freedom for humanity came into view in those days of a new birth. Both the possibility of the introduction of new sciences and of new arts and the power of utilizing all new intellectual and physical forces came together. The steam engine could not earlier have taken form, and, taking form, it could not have promoted the advance of civilization in the earlier centuries. The invention becoming possible of development and application, the promotion of the arts and of all forms of human activity became a possible consequence of its final successful introduction into the rude arts that it was to so effectively promote and improve.

But the work of these inventors was in itself but little more important than that of the Greek inventor of the steam ælopile, for each brought forward a machine which was, from a business point of view, utterly impracticable, and which, in each case, only served to show that a better device might prove useful and lead the way to its introduction. The merit of the inventors of the eighteenth century was that they were _able_ to lead the way, to point out the path to success, to furnish evidence of the value of the coming, crowning invention. The "fire engines," as they were then called, of these now famous men were merely contrivances by the use of which the pressure of confined steam of high tension could be brought to act on the surface of a mass of confined water, forcing it downward into pipes through which it was led off and upward to a higher level; and thus a mine could be drained, ineffectively and expensively to be sure, but vastly more satisfactorily than by the animal power of the time. The machine of Savery was the best of all; but that was only a somewhat improved and manageable rearrangement of the engines of Papin and Worcester. And, after all, Papin, the greatest man of science perhaps of his time, died in poverty; Worcester languished in prison his whole life, and the later efforts of his widow brought nothing by way of a return for his invention; nor did either they or their successor, Morland, make the introduction of the engine either general or remunerative.

Savery, coming on the stage at more nearly the right time to seize upon an opportunity, gained more than either of his predecessors; but we have no evidence that he ever acquired any large compensation or met with any remarkable business success in the introduction of the rude engine which bore his name; nor did Desaguliers, the great philosopher, or even Smeaton, the great engineer, of the later years of that century, make any great success of it. It was reserved for Watt to reap the harvest. But, though he so effectively reaped where his predecessors had sown, Watt is not the greatest of the inventors of the steam engine, if we rate his standing by the magnitude of the improvement which marked his reconstruction of the engine.

It was NEWCOMEN who made the modern steam engine.

When Newcomen came forward the labors of Worcester in Great Britain had sufficed to attract the attention of all intelligent men to the character of the problem to be solved, and to convince them of its importance and promise. The work of Savery had shown the practicability of the solution of the problem, both in mechanics and finance. He succeeded, though under great disadvantages and comparatively inefficiently. Once the task had been performed, though ever so rudely, the rest came easily and promptly. The defects of the Savery system were at once recognized; its great wastes of heat and of steam were noted, and the fact that they were inherent in the system itself was perceived. A complete change of type of machine was obviously requisite; it was this which constituted the greatest invention in the whole history of the steam engine, from Hero's time to our own; and to Newcomen we owe more than to any other man who ever lived, the value of the invention itself being considered, and the importance of the services of its introducer being left out of consideration. No such complete and vital improvement and modification of the machine has ever been effected by any other man, Watt and Corliss not excepted. Newcomen and his comrade Calley--we do not know how the honors should be divided--produced the modern steam engine. Its predecessor, the Savery engine, had been a mere steam "squirt." Newcomen constructed an engine. Savery built a simple combination of cylindrical or ellipsoidal vessels which wastefully and at once performed all the several offices of engine, pump, condenser, and boiler; Newcomen divided the several elements among as many parts, each especially adapted to the performance of its task in the most effective manner--the condenser excepted; for that was Watt's principal invention--and thus produced the first steam engine in the modern sense of that term.

It was Newcomen, not Watt, who gave us the train of mechanism that we now call the steam engine. It is to Newcomen, rather than Watt, that we owe the highest honors as an inventor in this series of the most important of all the products of the inventive genius of mankind. Newcomen brought into existence a new, the modern, type of engine, and effected the greatest revolution that has been recorded in the history of the arts. Without Newcomen, there might have been no Watt; without Watt, there very possibly may not even yet have been brought into existence that giant of our time, whose mighty powers are employed more effectively than ever those of Aladdin's genii, in building palaces, in transporting men and material, in doing the work of the whole world; promoting the welfare of the race, in a single century, more than had all the forces of matter and mind together in the whole previous history of the world. Newcomen laid down a foundation beneath our whole economic system, out of sight, almost, but the essential base, nevertheless, on which Watt and his successors have carried up the great superstructure which seems to us to-day so imposing; which is so tremendous in magnitude, importance, and result. If to any one man could be assigned the credit, it is Newcomen who is to be considered the inventor of the steam engine.

James Watt, indisputably the great inventor that he was, found the steam engine ready to his hand, applied himself to its improvement, and made it substantially what it is to-day. His most important work, the most unique service performed by him, was, however, that of its adaptation and introduction to do the work of the world. James Watt was the inaugurator of the era of refinement of the machine already invented, and the greatest of its builders and distributors. His inventions were all directed to the improvement of its details, and his labors to its introduction and its application to the myriad tasks awaiting it. By the hands of Watt it was made to pump water, to spin, to weave, to drive every mill; and he it was who gave it the form demanded by Stephenson, by Fulton, by the whole industrial world, for use on railway and steamboat, and in mill and factory, throughout the civilized countries of the globe. It was this great mechanic who showed how it might be made to do its work with least expense, with highest efficiency, with greatest regularity, with utmost concentration of power.

The grand secret of his success was historical and economic, as much as scientific and mechanical. He brought out his inventions just when the world was economically and historically ready for them. The age of authority was past, that of freedom was come; the period of political and ecclesiastical tyranny was gone by, and that of the spontaneous development of man was arrived. The great invention was offered to a world ready and needing it, and, more than all, competent, for the first time in history, to make and use it.

James Watt was himself a product of the modern scientific spirit. He was a man so constituted mentally that he could apply scientific methods to problems which his logical and clairvoyant mind could readily and exactly formulate the instant he was led to their consideration in the natural course of his progress. He was the ideal great inventor and mechanic. With inventive genius he combined strong common sense--not always a quality distinguishing the inventor--clear perception, breadth of view, and scientific method and spirit in the treatment of every question. His natural talent was re-enforced by an experience and an environment which led him to develop these ways and this mental habit. His trade was that of an instrument maker, his position was that of custodian and repairer of the apparatus of Glasgow University. He had for his daily companions and stimulus the great men and ozonized atmosphere of that famous institution. He kept pace with advancing science, and was imbued, both naturally and through contact with its promoters, with that ambition and those aspirations which are the life element of all progress, whether scientific or other. He was aware of the nature of the problems seeking solution at the time, and familiar with the state of his own art and that of the great mechanicians about him. Everything was favorable to his progress, so soon as he should be given an opportunity to take a step in advance and to come into sight at the front. The man and the time were both ready, and all conditions, internal and external, social and personal, were favorable to his development.

The invention upon which Watt was to improve was at his hand. A word in regard to its status at the moment will throw some light upon that of Watt and his creation. Newcomen had, as we have seen, produced the modern type of steam engine as an original and wholly novel invention. But this machine, marvelous as an advance upon pre-existing forms of the steam engine, was still, as seen in the light of recent knowledge and experience, exceedingly defective. The purpose of a steam engine is to convert into usefully applicable power the hidden energy of fuel, stored ages ago in the earth, by transformation, through the action of vegetation, from the original form, the heat of the sun, into an available form for reconversion, through thermodynamic operations. In this process of reconversion, whatever the nature of the machine used in the operation, there are invariably wastes, both of heat required for conversion into power and of the power thus produced. That machine which effects the most complete transmutation of the heat supplied it into mechanical power, which wastes the least amount of heat supplied and of power produced, is the best engine, and constitutes an advance over every other.

It was this reduction of wastes that made the Newcomen engine so much superior to that of Savery. The latter was by far the simpler and less costly construction; but its enormous losses, both of heat and of power, mainly the former, however, made it an extravagant expenditure of money to buy and use it. The Newcomen engine, costly and cumbrous, comparatively, nevertheless wasted so much less heat and steam and fuel that no one could afford to buy the cheaper machine. Before considering what Watt accomplished, we may find it profitable to examine into the nature of the wastes which characterized this later and better machine on which he effected his improvements.

The Newcomen engine consisted of a steam boiler, a steam cylinder, a beam and a set of pumps. By making the boiler do its work separately, the engine acting independently, and the pumps as a detached portion of the mechanism, this inventor had reduced to an enormous extent those wastes of heat and of steam and of fuel which were unavoidable in the older machines in which all these parts were represented by a single vessel, or by two at most, in each element. In the Savery engine, the steam entering first heated up the interior of the working vessel to its own temperature, and held it at that temperature in spite of the cooling influence of the water present. This consumed large quantities of heat. It then was compelled to surrender probably much greater quantities still to the water itself, coming in direct contact as it did with its surface. If the water was agitated, either by the currents produced during its ingress or by the impact of the steam entering the vessel, this heating action penetrated to considerable depths and perhaps even warmed the whole mass very far above its initial temperature. This constituted another and a very serious loss. Then, again, as the water was gradually driven out of the containing vessel by the steam pressing on its surface, new portions of the vessel and new masses of water were continually brought in contact with the hot steam, taking its full temperature, and thus, often, probably, finally heating the whole mass of the forcing vessel, and a large proportion of the water as well, up to the temperature, approximately at least, of the steam itself. Thus in many instances, if not always, vastly more heat and steam were wasted, in this undesirable heating of water and forcing vessel, than were usefully employed in the legitimate work of raising the water to a higher level. In fact, in some cases in which these quantities were measured, the wastes were one hundred times as much as the work done. One per cent. of the heat supplied did the work; while ninety-nine per cent. was thrown away. One dollar or one shilling expended for fuel to do the work was accompanied by an expenditure of ninety-nine dollars or shillings thrown away, because of the imperfections of the system and machine. The whole history of the development of the steam engine has been one of gradual reduction of these wastes; until to-day, our best engines only compel us to spend five dollars for wastes to each dollar paid out for useful work. A business man would think that amply extravagant, however, and the man of science is continually seeking methods of evading these losses, a large proportion of which are now apparently unavoidable in heat engines, by finding some new system of heat and energy transformation.

Watt was the instrument maker and repairer at Glasgow University in the year 1763. His companions were, among others, the professors of natural philosophy and of mathematics in the university. Their conversation and their frequent presentation of practical and scientific questions and problems stimulated his naturally inquiring and inventive mind to the pursuit of a thousand interesting and promising schemes for the improvement of existing methods and machinery. Dr. Robison, then a student, suggested the invention of a steam carriage for use on common roads, and the young mechanician at once began experiments that, resulting in nothing at the time, were nevertheless continued, in one or another form, until all modern applications of steam came into view. Dr. Black taught Watt chemistry, then a newly constructed science, and led him on to the discovery, finally made by them independently, of the fact and the magnitude of the latent heat of steam; the discovery coming of a series of scientifically planned and accurately conducted investigations, such as the man of science of to-day would deem creditable. The treatises of Desaguliers and others on physics gave Watt a knowledge of that domain of natural phenomena which stood him in good stead later, when he attempted to apply its principles to the reduction of the wastes of the steam engine.

It was while at Glasgow University, working under such influences and in such an atmosphere of intellectual activity, that the accident of the Newcomen model engine needing repair brought to the mind of Watt the opportunity which, availed of at once, made him famous and gave the world its greatest aid, its most powerful servant. The observing mind of the great mechanic immediately noted its defects, sought their causes, found their remedy. He discovered, at once, that the quantity of steam entering the cylinder of the little engine has four times the volume of the cylinder receiving it: in other words, three-fourths of that steam must be condensed immediately on entrance. This meant, evidently, that only one-fourth of the steam supplied was utilized, and even then inefficiently, in doing its work. The reason of this was as easily seen, immediately the fact was revealed. As Watt himself expressed it, the causes of this loss, causes which would obviously be exaggerated in a small engine, were: "First, the dissipation of heat by the cylinder itself, which was of brass and both a good conductor and a good radiator. Secondly, the loss of heat consequent upon the necessity of cooling down the cylinder at every stroke in producing the vacuum. Thirdly, the loss of power due to the pressure of vapor beneath the piston, which was a consequence of the imperfect method of condensation." This much determined, the next step looked toward the confirmation of his conclusions and the remedy of the defects.

To meet the first difficulty he made a cylinder of wood, soaked in oil and baked, a non-conducting and non-radiating material. Then he was able to determine with some accuracy the quantities of steam and injection water used in the engine; and a comparison with the original cylinder and its operation showed that not only four times the quantity of steam, but also four times the amount of injection water was used as was necessary, assuming wastes checked. Further scientific research on the part of Watt gave him measures of specific heats of the metals and of wood, the specific volumes of steam at various working pressures, the evaporative efficiency of boilers, the pressures and temperatures of steam in the boiler under specified conditions, the quantities of steam and of water required for the operation of his little condensing engine.

Then came his enunciation of the grand principle of economy in the construction and operation of the steam engine: "Keep the cylinder as hot as the steam which enters it," as he expressed it. This was Watt's guiding principle, as it has been that of all his successors in the improvement of the economic performance of the steam engine and of all other heat engines. The great source of waste is the dispersion of heat, uselessly, which should be applied to the production of work by its transformation, thermodynamically, into the latter form of energy. The second form of waste is that of power thus produced in the unprofitable work of moving the parts of the engine itself; and the third is that of heat by transfer, without transformation, by conduction and radiation to surrounding bodies. In modern engines, the latter is but three or five per cent., in the best cases; the second waste constitutes perhaps ten per cent.; while the first of these losses amounts very usually to seventy per cent., of which last one-third or one-fourth is of the kind discovered by Watt, the rest being the thermodynamic waste incident to all known methods of operation of heat engines, and apparently unavoidable. In our very best and largest engines, the waste found by Watt to constitute three fourths of all heat supplied has been brought down to ten per cent., a fact which well exemplifies the advances made since his time of apprenticeship by himself and his successors of this nineteenth century. The steam engine of to-day, in its most successful operation, gives us twenty-five times as much power from a pound of coal as did the engine that the great inventor sought to improve: this is the magnificent fruit of that one discovery of James Watt, and of application of the simple principle which he so concisely and clearly stated.

The method adopted by Watt to secure a remedy, so far as practicable, of this defect of the older machine was as simple and as perfect as was the principle which it embodied. He first removed from the cylinder the prime source of its wastes; providing a separate condenser, and thus avoiding the repeated chilling of its surfaces by the cold water used in condensing the steam at exhaust, and also permitting its strokes to be made with far greater frequency, thus giving less time for cooling by the influence of the remaining vapors after condensation. He next went still further, and provided the cylinder with a closed top, keeping out the air, and a "jacket" of hot boiler steam to _keep_ it as hot as the steam which entered it. These were the two great improvements which converted the first real steam engine into an economical form of heat engine and essentially finished the work so grandly begun by Newcomen and Calley. These changes gave us the modern steam engine; and these are Watt's first and greatest, but by no means only, contributions to the production of the modern world with all its comforts, its luxuries and its opportunities for material, intellectual and moral advancement of individual and of race. His work was to this extent complete in 1765.