THE SORTING DEMON OF 

 MAXWELL. 



^Abstract of a Friday evening Lecture before the Royal 

 Institution of Great Britain, February 28, 1879 (Proc. 

 R. I. vol. ix. p. 113).] 



THE word- "demon," which originally in Greek 

 meant a supernatural being, has never been 

 properly used as signifying a real or ideal per- 

 sonification of malignity. 



Clerk Maxwell's "demon" is a creature of 

 imagination having certain perfectly well defined 

 powers of action, purely mechanical in their 

 character, invented to help us to understand the 

 " Dissipation of Energy " in nature. 



He is a being with no preternatural qualities, 

 and differs from real living animals only in 

 extreme smallness and agility. He can at 



