August 29, 1884.] 



SCIENCE. 



163 



the highest flights of modern mathematics. 

 Moreover, the lecturer on the great doctrine 

 of the conservation of energy will find that this 

 book is founded upon this doctrine, and opens 

 with its fundamental equations. Lord Ray- 

 leigh pointed out, before the appearance of 

 this treatise, the use of a peculiar function, ex- 

 pressing the law of decay, so to speak, and 

 subsidence of 

 impulses in 

 any system or 

 configuration ; 

 and although 

 he probably 

 saw its chief 

 employment 

 was in the dis- 

 cussion of the 

 dissipation, 

 and frittering 

 into heat, of 

 sound - vibra- 

 tions in any 

 complicated 

 system, yet he 

 probably saw, 

 in common 

 with Maxwell, 

 that the dissi- 

 pation func- 

 tion could be 

 employed i n 

 electricity to 

 express the os- 

 cillation and 

 change of elec- 

 trical i n d u c- 

 tion - currents, 

 also, into other forms of energy. The intelli- 

 gent reader of Rayleigh's ' Theory of sound ' 

 has a great intellectual pleasure in tracing in 

 it the methods of reciprocit}^ of similitudes, the 

 illustrations of the conservation of energy, and 

 must rise from its perusal with a clearer notion 

 than he has had before of the unity of physi- 

 cal forces, of the great modern truth of the 

 equivalence between work and heat. 



Since Lord Rayleigh has become director 



of the Cavendish laboratory, he has organ- 

 ized its scientific work, and has made it a 

 centre of physical investigation as well as 

 of instruction. His determinations of the 

 ohm, which were presented to the Paris con- 

 ference of electricians, 1883-84, were gener- 

 ally regarded as the most accurate, and formed 

 the basis of the unit of electrical resistance now 



formally adopt- 

 ed. He has 

 lately investi- 

 gate d the 

 methods of ob- 

 taining a prac- 

 tical unit of the 

 strength of an 

 electrical cur- 

 rent, and has 

 shown that the 

 method by the 

 deposition of 

 silver is capa- 

 ble of a high 

 degree of ac- 

 curacy. It 

 will be seen 

 that he unites 

 unusual quali- 

 ties for direct- 

 or of physical 

 science, great 

 mathemat i c a 1 

 ability, and 

 the power to 

 execute and 

 supervise sci- 

 entific investi- 

 gation. 



Lord Ra3 T leigh's countenance will soon be- 

 come familiar to every American man of 

 science ; and we hope that even the uneducated 

 American will learn to see in him, not the lord 

 of the manor of Terling and the patron of 

 two livings, but a peer of the distinguished 

 school of mathematicians of Cambridge, Eng., 

 the pre-eminence of which, in mathematical 

 science, American centres of learning can 

 honor, but not dispute. 



