SKETCH OF DR. JAMES P. JOULE. 107 



Prof. Tyndall, although the English champion of Mayer's claims, 

 did ample justice to his own countryman, as the following passage 

 shows : " It is to Mr. Joule, of Manchester, that we are almost wholly 

 indebted for the experimental treatment of this subject. With his 

 mind lirmly fixed on a principle, and undismayed by the coolness with 

 which his first labors appear to have been received, he persisted for 

 years in his attempts to prove the invariability of the relation be- 

 tween heat and ordinary mechanical force. He placed water in a suit- 

 able vessel, agitated it by paddles moved by measurable forces, and 

 determined the elevation of temperature ; he did the same with mer- 

 cury and sperm-oil. He caused disks of cast-iron to rotate against 

 each other, and measured the heat produced by their friction. He 

 urged water through capillary tubes, and measured the heat thus gen- 

 erated. The results of his experiments leave no doubt upon the mind 

 that, under all circumstances, the absolute amount of heat produced 

 by a definite amount of mechanical force is fixed and invariable." 



For this great scientific achievement the Royal Medal of the Royal 

 Society was awarded to Mr. Joule in 1852 ; and eight years later, when 

 men of science began more fully to apprehend the great value of the 

 discovery, he was presented also with the Copley Medal of the Royal 

 Society. On that occasion. Sir Edward Sabine, the president, allud- 

 ing to the former award, used the following words : " Both awards re- 

 fer to the same experiments, and are substantially for the same great 

 step in natural philosophy. You are all aware that a great principle 

 has been added to the sum of human knowledge — one fruitful in con- 

 sequences in a thousand ways, and which, being accepted among un- 

 disputed truths, is now embodied, without question, alike in the most 

 wide-ranging speculations and the most matter-of-fact practice. The 

 award of two medals for the same researches is an exceedingly rare 

 proceeding in our society, and rightly so. The council have, on this 

 occasion, desired to mark by it, in the most emphatic matter, their 

 sense of the special and original character and liigh desert of Mr. 

 Joule's discovery. No words of mine could add to the value of the 

 award." 



Dr. Joule has figured but little in the fields of popular science, hav- 

 ing only given a few lectures to the people in Manchester, and pub- 

 lished no book, as we are aware, of any kind. But his contributions 

 to scientific periodicals and the transactions of learned societies are 

 very numerous, and give the results of prolonged and incessant origi- 

 nal investigations, extending through many years. He became a 

 Fellow of the Royal Society in 1 850, received the degree of B. C. L. 

 from Oxford, of LL. D. from the Universities both of Dublin and of 

 Edinburgh, is a corresponding member of the Institute of France, 

 and was President-elect of the British Association for the Advance- 

 ment of Science, which met at Bradford last year. 



