Annual Report of the Council. 259 



. Rudolf Clausius, who died on August 24th, 1888, 

 was connected with us even more by the close relation of 

 his distinctive work with that of Dr. Joule, than by the fact 

 of his election as one of our honorary members. He was 

 born on the 2nd of January, 1822, one of the youngest of a 

 family of eighteen. For the sake of his younger brothers, 

 he felt himself bound to discontinue his studies in Berlin 

 and gain his own livelihood, first as a tutor, later as a 

 schoolmaster; ultimately graduating at Halle in 1848. In 

 1855 he was made Professor in the Polytechnicum at Zurich, 

 and in 1857 in the University of that town. In 1867 he 

 was called to Wiirzburg, and in 1869 to Bonn, where he 

 spent the rest of his life (declining invitations to Strassburg 

 and Gottingen) in the discharge of his duties and the cease- 

 less pursuit of his studies. The establishment of the 

 equivalence of heat and work by Joule and his fellow- 

 workers was the great scientific advance in Clausius' student 

 days, and it decided the direction of his life work. The 

 material theory of heat had led to no scientific result 

 comparable with Carnot's theory, and the destruction of the 

 material theory by the mechanical had left this important 

 and apparently correct result without support. Recognising 

 the inherent merits of Carnot's work, Clausius undertook 

 the examination of it from the point of view of the new 

 mechanical theory of heat, and in his first investigation on 

 the subject, presented to the Berlin Academy in 1850, he 

 showed that a new and independent principle in thermo- 

 dynamics was necessary, from which by an indirect method 

 he deduced Carnot's Theory. Considering Joule's Principle 

 of the equivalence of heat and work as the First Law, 

 Clausius' Principle of the equivalence of transfor- 

 mations, in one of its various forms, is accepted as the 

 Second Law of thermo-dynamics. Clausius has himself 

 stated it in different ways ; we give it thus: — It is incon- 

 ceivable that heat, unaided by any external agency, 



