November 7, 1884.] 



SCIENCE. 



431 



of heat as a mode of motion. He was the 

 first to propose the use of an absolute thermo- 

 dynamic scale for the measurement of tempera- 

 ture ; and, in his paper on the electrodynamic 

 qualities of metals, he presented his discovery 

 of the electrical convection of heat, and of a 

 great number of important relations between 

 thermal and electric properties of matter. 

 Perhaps the most striking of the results to 

 which his studies 

 in thermodynamics 

 led him was the 

 theory of the dissi- 

 pation of energy. 



The almost ran- 

 dom list of papers 

 which we gave 

 above was designed 

 to illustrate the va- 

 riety, rather than 

 the importance, of 

 Sir William Thom- 

 son's work ; but it 

 is hardly necessary 

 to say that many 

 of his researches 

 on subjects very 

 wide apart have 

 been profound and 

 important. His 

 great investi- 

 gations on the sub- 

 ject of vortex mo- 

 tion, to which he 

 has devoted much 

 attention for so 

 man}- years, his researches on the tides, 



his 



contributions to hydrodynamics, his researches 

 on the physical condition of the earth, have all 

 been of signal importance ; and the highly 

 original method of attacking the problem of 

 the wave- theory of light, of which he gave 

 some account in his recent Johns-Hopkins lec- 

 tures, has long been occupying his mind, and 

 ma}' fairly be expected to give rise, in the not 

 very distant future, to results rivalling in value 

 any of his former discoveries. 



Besides his contributions to the advance- 



ment of pure science, Sir William Thomson" 

 has been the originator of improvements and 

 inventions of the highest immediate practical 

 utility. The most prominent of his services 

 of this character have been those connected 

 with submarine telegraphy. Space does not 

 permit our entering into details : but it may be 

 mentioned, that he discovered the law of the 

 'retardation of signals,' which was the chief 



preliminary diffi- 

 culty to be faced 

 by those consider- 

 ing the feasibility 

 of using a cable 

 stretching u n d e r 

 the ocean, from 

 the old to the new 

 world ; that, to 

 meet this difficulty, 

 he invented the 

 ' mirror galvanom- 

 eter,' which, when 

 the cable of 1858 

 came to be laid, 

 was employed dur- 

 ing the brief period 

 of its successful 

 operation; and 

 that, when this ca- 

 ble broke, on ac- 

 count of difficulties 

 and imperfections 

 connected with its 

 submersion, he de- 

 voted himself with 

 signal success to 

 improving the construction of cables, and 

 the mechanical arrangements for their sub- 

 mersion. 



The very great benefits conferred upon the 

 world by the labors of Thomson and others, 

 who contributed to overcoming the difficulties 

 which were so triumphantly surmounted in 

 1866, were recognized by the bestowal upon 

 them of the honor of knighthood. Other 

 important improvements in telegraphy are 

 due to him, but we must omit mention of 

 them. 



