VICE-PRESIDENT OF THE SOCIETY. 141 



method suggested by Thomson, that of forcing air along 

 a pipe with a very narrow neck in it, and measuring the 

 temperature on each side of the neck, was adopted, and 

 after two years' work, gave a cooling effect perfectly con- 

 sistent with the deviation from Boyle's law for air, hydrogen, 

 and carbonic acid. 



The experimental research was very severe, and involved 

 much larger apparatus than anything Joule had previously 

 used, the final results being obtained in the Salford 

 Brewery, only by the aid of a steam engine developing three 

 horse-power, and even then the greatest differences of tem- 

 perature with air were very small. 



As both the research and the method employed were 

 suggested by Sir William Thomson, it is, here, chiefly 

 interesting as showing how Joule was occupied during the 

 years 1852 and 1853, and as affording an instance of the 

 unique powers he displayed in thermal mensuration. 



In June, 1850, Joule visited Mr. Tappenden in London ; 

 and was admitted a Fellow of the Royal Society by the 

 Earl of Rosse, being introduced by Dr. Forbes. In July, 

 with his wife, baby, nurse, and sister, he went to Edinburgh 

 to the British Association. 



Joule held the office of Secretary in this Society from 

 1846 to 1850. His colleague during the last three years 

 was Mr. E. W. Binney, with whom the friendship thus 

 begun became very intimate, and lasted to Mr. Binney's 

 death in 1881. In 1850 Joule vacated the office of Secretary 

 on being elected one of the four Vice-Presidents, Sir 

 William Fairbairn being another Vice-President, and Eaton 

 Hodgkinson President. The interest Joule took in the 

 work of the Society during these years was a subject on 

 which Mr. Binney often remarked in later years. 



