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.