COMMEMORATION OF PROF. HENRY A. ROWLAND. 741 



years, previous to this time, however, he had hern busily engaged on 

 what proved to be, in its influence upon his future career, the most 

 important work of his life. To climb the ladder of reputation and 

 success by simple, easy steps might have contented Rowland, but it 

 would have been quite out of harmony with his hold spirit, hi- extraor- 

 dinary power of analysis, and his quick recognition of the relation of 

 things. By the aid of apparatus entirely of his own construction and 

 by methods of his own devising, he had mad.' an investigation both 

 theoretical and experimental of the magnetic permeability and the 

 maximum magnetization of iron, steel, and nickel, a subject in which 

 he had been interested in his boyhood. On dune it. L873, in a letter 

 to his sister, he say-: "1 have just sent oil' the results of my experi- 

 ments to the publisher and expect considerable from it: not. however, 

 filthy lucre, but good, substantial reputation." What he (lid gel from 

 it, at first, was only disappointment and discouragement, li wasmore 

 than once rejected because it was not understood, and finally he ven- 

 tured to send it to Clerk Maxwell, in England, by whose keen insight 

 and profound knowledge of the subject it was instantly recognized and 

 appraised at its full value. Regretting that the temporary suspension 

 of meetings made it impossible for him to present the paper at once to 

 the Royal Society, Maxwell said he would do the next best thine-, which 

 was to send it to the Philosophical Magazine for immediate publication, 

 and in that journal it appeared in August, L873, Maxwell himself hav- 

 ing corrected the proofs to avoid delay. The importance of the paper 

 was promptly recognized by European physicists, and abroad, if not 

 at home, Rowland at once took high rank as an investigator. 



In this research he unquestionably anticipated all others in the dis- 

 covery and announcement of the beautifully simple law of the mag- 

 netic circuit, the magnetic analogue of Ohm's law. and thus laid the 

 foundation for the accurate measurement and study of magnetic per- 

 meability, the importance of which, both in theory and practice during 

 recent years, it is difficult to overestimate. It has always seemed to 

 me that when consideration is given to his age. his training, and the 

 conditions under which his work was done, this early paper gives a 

 better measure of Rowdand's genius than almost any performance of 

 his riper } r ears. During the next year or two he continued to work 

 along the same lines in Troy, publishing not many, but occasional. 

 additions to and developments of his first magnetic research. There 

 was also a paper in which he discussed Kohlrausch's determination of 

 the absolute value of the Siemens unit of electrical resistance, fore- 

 shadowing the important part which he was to play in later years in 

 the final establishment of standards for electrical measurement. 



In 1875, having been appointed to the prof essorship of physics in 

 the Johns Hopkins University, the faculty of which was just then 

 being organized, he visited Europe, spending the better part of a year 



