SKETCH OF RUDOLF CLAUSIUS. 121 



never allowed to lose sight of the essential meaning of the symbols 

 employed. . . . Any one wishing to gain a general acquaintance, 

 thorough as far as it goes, with the subject, can scarcely do so 

 with the expenditure of less time and labor than are required for 

 the perusal of this book. As a mathematical study the book may 

 replace some of the luxuriant growths of modern geometry and 

 analysis with great advantage to the brains of the student." 



In his later years Clausius was interested principally in the 

 study of the questions raised by dynamo-electric machines. He 

 published a theory of dynamo-motors in " La Lumiere elec- 

 trique," in 1884, in which he sought to fix more general equations, 

 resting on more solid theories than those in use ; but, notwith- 

 standing his memoir is marked by his peculiar qualities, the theo- 

 ries have not been accepted, and have only been partly, if at all, 

 confirmed by late researches. Yet it is to him that we owe a brill- 

 iant and clear exposition, and one of the first that was made, of 

 certain phenomena of self-induction. 



The Franco-German War occurred while Prof. Clausius was at 

 Bonn. Although he was not liable to draft in the general mobiliza- 

 tion, he was engaged in the ambulance service, and diligently inter- 

 ested himself in the care of the wounded. After the war was over, 

 the German Government decorated him with the order of the Iron 

 Cross, and the French with that of the Legion of Honor. The rea- 

 son of the French awarding such a distinction upon an eminent 

 German at such a time, when resentments still lively enough were 

 at their height, is most probably to be found in the fact that he 

 did not observe distinctions of nationality in his attentions. The 

 incident affords a striking illustration of the effect of scientific 

 studies in widening the range of thought and sympathy. 



Prof. Clausius is described by M. Langlois as having been a 

 teacher of remarkable clearness and simplicity in his explana- 

 tions. His instruction was marked by a particular care to keep 

 always within the limits of true physical principles. While he 

 was remarkably versed in mathematical methods, he always kept 

 the physical notations in the minds of his readers, and never 

 allowed himself to be carried by his analyses into the regions of 

 too vague conceptions. Mr. G. W. de Tunzelmann agrees with 

 this conclusion in his obituary sketch in " Nature," saying that 

 Clausius formed a center of attraction at Bonn, " not only as a 

 great investigator, but as a teacher of almost unrivaled ability. 

 The secret of his powers as a teacher may easily be guessed from 

 the study of his published papers and treatises." The greater 

 part of his work, the writer adds, had the additional advantage of 

 being effected by the aid of comparatively simple analysis. 



Prof. Clausius was elected a foreign member of the Royal So- 

 ciety in 1868, and received its Copley medal in 1879. 



