366 JAMES CLERK MAXWELL. [CHAP. XII. 



and bilateral deflection of a galvanometer, affording a 

 possible explanation of Dr. Schuster's result. The 

 investigation proved that when a unit current passes 

 through a conductor of a square centimetre section, 

 its resistance does not differ from its value for in- 

 definitely small currents by 0*000,000,001 per cent. 



1873-9. The scene of these congenial labours was sur- 

 rounded with manifold associations, which his love 

 for Cambridge intensified. He had pleasant inter- 

 course with many persons there, and after a while 

 resumed the habit of occasional essay writing. Under 

 the name of Ernus (or pic-nic) a club of older 

 men was formed, differing little apparently from the 

 "Apostles," except in the greater seriousness of the 

 discussions. Dr. Lightfoot (now Bishop of Durham) 

 and Professors Hort and Westcott were members of 

 this little circle of congenial spirits. Maxwell's 

 contributions, containing his matured thoughts on 

 various speculative questions; will be found in Chapter 

 XIII. It may be remarked generally that the most 

 marked feature of his later life was an ever-increasing 

 soberness of spirit, and a deepening inward repose, 

 which took nothing from the brightness of his com-, 

 panionship, but rather kept fresh the inexhaustible 

 springs of cheerfulness and humorous mirth in him. 

 The beginnings of such " life in earnest " may be 

 traced far back, but are most obviously perceptible 

 in his third year at Cambridge (1853), 1 in the summer 



How readily his thoughts took a serious turn, even in the earlier 



