ERASMUS DARWIN LEAVITT. 841 



which, with the Lehrbuch above referred to, form a monumentar 

 record of scientific activity. To pass tliis in review is hardly practi- 

 cable within the space of a short memorial sketch. He has made- 

 contributions to many branches of physical research, and through the 

 " Lehrbuch" and the great variety of apparatus which bears his name,, 

 his relation to his chosen science, both in his own country and abroad, 

 has been of the most intimate kind. Rather by way of illustration 

 than with any purpose of presenting an adequate review of his scientific 

 work, certain of his papers may be cited. 



In the category of precise physical measurements we may notice 

 first of all his determination of the ohm and a considerable number of 

 papers upon the measurement of the earth's magnetic constants. 

 In the course of these latter studies new methods and new apparatus 

 were developed many of which are still fully equal to the most exacting 

 requirements of modern quantitative science. The determination, 

 in association with his brother Wilhelm, of the electrochemical equiva- 

 lent of silver also finds a place in this period of his activity. 



The name of Kohlrausch is perhaps most familiarly associated with 

 the work on electrical conductivity in solutions which owes its founda- 

 tion (the applicability of Ohm's Law to conductors of the second class) 

 and much of its modern development (the theory of polarization, 

 dissociation, and ionic conductivity) to the work of Kolilrausch and 

 his pupils, ainong whom were included Arrhenius, Barus, Nernst, and 

 many others hardly less distinguished. 



Arthur L. Day. 



ERASMUS DARWIN LEAVITT (1836-1916) 



Fellow of Class I, Section 4, 187S. 



Erasmus Darwin Leavitt was born at Lowell, Mass. on October 27, 

 1836, and died in Cambridge, Mass. on March 11, 1916. He was 

 named for his father, who was given the name because of his father's 

 admiration for Darwin's grandfather. 



The public schools of Lowell furnished young Leavitt his education 

 up to the age of fourteen. After that he educated himself for the 

 profession of mechanical engineer, supplementing his work in various 

 machine shops with long and patient study far into the night. To 



