James Prescott Joule by Lord Kelvin
James Prescott Joule Portrait
The unveiling, last December, of a statue of Dr. James Prescott Joule, at Manchester, England, has given that city the possession of a work of art which will ever remain an ornament and an honor to it.
Joule’s work began in Manchester, was carried on in Manchester, and finished in Manchester. It began very early, when he was only nineteen years of age. He was not altogether a self-taught man in science. After a good ordinary school education, he had the inestimable benefit of the personal teaching of Dalton in chemistry. He and his elder brother Benjamin were favorite pupils of Dalton. They went to his house in the rooms of the Literary and Philosophical Society of Manchester for regular daily lessons, and were a little disappointed at first when they found that Dalton, instead of introducing them straight away to the grandeur of the atomic theory of chemistry, kept them to the grindstone, forced them to do their additions correctly, and held-up to them, as something essentially necessary for them to learn, the practice of trigonometry and the logarithmic tables. James Joule and his brother got great good from that early severe, almost hard, training by Dalton. They were both full of original brightness and acuteness in their observations. They went through the country, even before they came to be pupils of Dalton, making memoranda of what they saw and heard, an aurora borealis or a wonderful thunderstorm, or sounds of artillery or lightning, they could not tell which. Some of their journals they afterward showed to Dalton, who thought so well of their descriptions that in one instance he was able to say to them, “Those sounds you heard were not human artillery but they were the thunder of an outburst of lightning at sea forty miles south of Holyhead.”
The two brothers continued pupils of Dalton until the failure of his health; but for a year after that, and no doubt to the very end, they continued to receive ideas from that great man. It must not be thought that Dalton only taught them arithmetic and trigonometry. I rather emphasize that point with an eye perhaps to the young men who aspire to follow in Joule’s footsteps, and upon whom I wish to impress the conviction that it was hard work, early begun and persevered in and conscientiously carried out. That is the foundation of all great works, whether in literature, philosophy or science, or in doing good to the world in any possible way. In electricity and electro-magnetism Joule, I think I may say, was wholly self-taught. All he knew he learned from his own reading — from reading in text books and in Sturgeon’s Annals of Electricity, and also from conferences with Sturgeon himself. The Literary and Philosophical Society of Manchester has the distinguished honor of having been the cradle of Joule’s scientific childhood when it was Dalton’ s home, and of being afterward Joule’s life-long scientific harbor. From those early days he kept constantly in touch with that society.
Many of his most important papers were first given to the world there, and during the last years of his life he was an exceedingly regular, it might almost be said a constant, attendant at the meetings of the Society. An interesting and sympathetic memoir of Joule, with much important scientific information and judgment regarding his work, by Professor Osborne Reynolds, constitutes the sixth volume of the fourth series of its ” Memoirs and Proceedings.”
A great surprise that came out very early in Joule’s work was burning without heat — an absolutely novel idea which Joule developed most wonderfully and most magnificently by his experiments on the generation of heat in the voltaic battery. Joule was the first to develop the idea, and it came to him not as a bright flash of genius, but as the demonstrated result of years of hard, measuring, calculating work. This burning without heat was a fundamental idea that pervaded all Joule’s work. A few year’s later he expanded it in an admirable way.
About 1844, in a joint paper by himself and Scoresby, “On the Mechanical Powers of Electro-magnetism, Steam and Horses,” he brought out the startling but truly philosophical idea that when a man or any other animal walked uphill, only a part of the heat of combustion of his food was developed, and that it was only when the body was quiescent, or walking about on a level, or going downhill that the chemical attraction between the food and the oxygen dissolved in the blood developed its whole energy in animal heat. He showed, further, that a horse or a man employed in doing mechanical work against resistance was more economical of fuel than was any steam engine hitherto realized. This was a very far-reaching idea, and seemed to hold out prospects of greatly advancing the efficiency of the steam engine. That promise has not been lost.
It is due to Joule more than to any other individual that the great improvement of surface condensation is now universal, although it was very rarely practiced before 1860 or 1862. Between 1855 and 1862, Joule and I had a small steam engine fitted up in the stable of his father’s house, Oakfield, for use in our joint investigations on the thermic effects on fluids in motion. To that little steam engine Joule applied a surface condenser on an entirely new principle and plan, which gave us such good results that, starting from it, he undertook a special investigation on the surface-condensation of steam with the assistance of a grant from the Royal Society for the purpose. The results of this very elaborate investigation, communicated to the Royal Society on December 13, 1860, and published in The Philosophical Transactions, have proved to be of enormous practical importance. They led directly and speedily to the present practical method of surface-condensation, which is one of the most valuable improvements of the steam engine, especially for marine use, since the time of Watt.
But I have not yet touched upon Joule’s great fundamental discovery, the discovery which is first in every one’s mouth when asked what was Joule’s work? — The Mechanical Equivalent of Heat. It was not merely by a chance piece of experiment or of guessing that he stumbled on a result which was afterwards found to be of great value. It was measurement, rigorous experiment and observation, and philosophic thought all round the field of physical science that made the discovery possible to him. Very early, however, in his working time Joule brought out the mechanical equivalent of heat, and in a paper at the British Association at Cork, in 1843, published afterwards in The Philosophical Magazine, he gave the number “770.” Six years later a second determination gave him a result about 1/3 per cent, larger, and twenty-nine years later he completed a third determination. The result of this final investigation of Joule’s is 772.43 Manchester foot-pounds for the quantity of heat required to warm from 60° to 61° Fahrenheit, one pound of water weighed in vacuum, which is about 1/20 per cent, greater than the result of 1849 expressed in the same term.
In the year 1824 a great theory was originated by a very young man, who died only a few years later — Sadi Carnot, son of the Republican War Minister and uncle of the late president of the French Republic. It was he who made “Carnot’s theory” a household word throughout the world of science. Carnot’s theory gave an important fundamental principle regarding the development of motive power from heat. Joule’s work, on the other hand, so far as the mechanical equivalent was concerned, was the generation of heat by mechanical work. It was quite the middle of the century before Carnot’s theory began to attract attention; but Joule was early made acquainted with it, and after fighting a little against it, as differing from his own theory, he, of all others, took it up in the most hearty manner. I can never forget the British Association at Oxford in the year 1847, when in one of the sections I heard a paper read by a very unassuming young man who betrayed no consciousness in his manner that he had a great idea to unfold. I was tremendously struck with the paper. I at first thought that it could not be true, because it was different from Carnot’s theory, and immediately after the reading of the paper I had a few words of conversation with the author, James Joule, which was the beginning of our forty years’ acquaintance and friendship. On the evening of the same day that very valuable institution of the British Association, its conversazione, gave us opportunity for a good hour’s talk and discussion over all that either of us knew of thermodynamics. I gained ideas which had never entered my mind before, and I thought I too suggested something worthy of Joule’s consideration when I told him of Carnot’s theory.
Then and there in the Radcliffe Library, Oxford, we parted, both of us, I am sure, feeling that we had much more to say to one another and much matter for reflection in what we had talked over that evening. But what was my surprise a fortnight later when, walking down the Valley of Chamounix, I saw in the distance a young man walking up the road towards me and carrying in his hand something which looked like a stick, but which he was using neither as an Alpenstock nor as a walking stick. It was Joule with a long thermometer in his hand, which he would not trust by itself in the char-a-banc coming slowly up the hill behind him lest it should get broken. But there comfortably and safely seated on the char-a-banc was his bride — the sympathetic companion and sharer in his work of after years. He had not told me in Section A or in the Radcliffe Library that he was going to be married in three days, but now in the valley of Chamounix, he introduced me to his young wife.
We appointed to meet again a fortnight later at Martigny to make experiments on the heat of a waterfall (Sallanches) with that thermometer; and afterwards we met again and again and again, and from that time, indeed, remained close friends till the end of Joule’s life. I had the great pleasure and satisfaction for many years, beginning just forty years ago, of making experiments along with Joule, which led to some important results in respect to the theory of thermodynamics. This is one of the most valuable recollections of my life, and is, indeed, as valuable a recollection as I can conceive in the possession of any man interested in science. Joule’s initial work was the very foundation of our knowledge of the steam engine and steam power. Taken along with Carnot’s theory it has given the scientific foundation on which all the great improvements since the year 1850 have been worked out, not in a haphazard way but on a careful philosophical basis. James Watt had anticipated to some degree in his compound engine and his expansive system the benefits now realized, but he was before his time in that respect and he had not the complete foundation which Joule’s mechanical equivalent and Carnot’s theory have since given for the improvement of the steam engine.