44 COMMENCES SECOND RESEARCH. 



to make the duty per I lb. of zinc superior to the duty of the 

 best steam engines per lb. of coal ; and even if this were 

 attained, the expense of the zinc and exciting fluids of the 

 battery is so great when compared with the price of coal as 

 to prevent the ordinary electro-magnetic engine being useful 

 for any but very peculiar purposes." 



Joule was then just 22 years of age. He had been 

 working intensely for three full years, devoting his whole 

 time to the research while living in his father's house. As 

 regards his object in starting this research, he had met with 

 complete failure. His papers had been obscurely published as 

 letters in Sturgeon's "Annals of Electricity" and do not seem 

 to have caught the attention of anyone capable of apprecia- 

 ting their merit, even if they have had a reader. But he shows 

 no sign of flagging. He is carried on by his interest in his 

 work and the knowledge he is acquiring. He has made him- 

 self master of the subject of magnetism, and is in many res- 

 pects in front of anyone. He has mastered the difficulties of 

 measuring 'work,' and electricity in absolute units ; and has 

 not only proved his weapons, but tasted the excitement and 

 delight of actual battle, passing the border hitherto trodden. 

 His mind, too, had been filled with philosophical thoughts by 

 the laws he had discovered, while his curiosity had been 

 excited by the unexplained incidents of his experiment. 

 He is at no loss how to proceed, for after measuring his 

 currents, and realizing the induced resistance of his machines, 

 and while yet occupied in clearing up the outstanding ques- 

 tions, such as the limits imposed by the saturation of the 

 magnets, he has already started a new research, and, this 

 time, with a purely philosophical object. 



