Manchester Memoirs, Vol. Ixv. (192 1), No. 3 7 



electro-magnetic engines, magnetic storms, polarisation of 

 platinum plates, mercurial air pumps and telescopic oscilla- 

 tions. 



In these remarkable Papers and Notes he enunciated 

 many new and important truths. His interests were many 

 and his experimental work was very beautiful ; each paper is 

 worthy of a separate lecture but it is only possible for me to 

 deal here with some of his discoveries. 



It is necessary to note the nature of Joule's training and 

 the progress of his leading experimental work. Joule's father 

 was a man of wealth and position whose sons were educated 

 at their own homes by tutors. Joule had the advantage of 

 some training, by the great Dalton, in mathematics, but 

 Dalton's illness prevented him instructing his pupil in 

 chemistry. Joule had no college or university training. He 

 was born in the year 181 8, and in the year 1838, at nineteen 

 years of age, he began his experimental work by an attempt 

 to improve Sturgeon's electro-magnetic engine. He had no 

 idea as to the nature of mechanical work, and he then saw no 

 objection to perpetual motion. In a letter written in 1839 ne 

 stated : — 



" I can hardly doubt that electro-magnetism will ulti- 

 mately be substituted for steam to propel machinery. If 

 the power of the engine is in proportion to the attractive 

 force of its magnets, and if this attraction is as the square 

 of the electric force, the economy will be in direct ratio of 

 the quantity of electricity, and the cost of working the 

 engine may be reduced ad infinitum. It is, however, yet to 

 be determined how far the effect of magnetic electricity may 

 disappoint these expectations." 



For three full years Joule experimented with the electro- 

 magnetic engine and measured the work done, the zinc con- 

 sumed in the battery and the current passing — the current 

 being measured in definite units with a galvanometer, and 

 ascertained the weight of water decomposed electrolytically ; 

 he also tested the effect of alterations in the construction and 

 winding of his electro-magnets. He exhausted the whole 

 subject in the most painstaking manner and ultimately he 

 concluded that he had failed irretrievably. In a lecture given 

 by him in the Victoria Gallery, Manchester, on February 16, 

 1 84 1, he stated : — 



" With my apparatus every pound of zinc consumed in 

 a Groves' battery produced a mechanical force (friction 



