13 



NOTE ON THE MAGNETIC EFFECT OF ELECTRIC 

 CONVECTION 



[Philosophical Magazine [5], VII, 442, 443, 18791 



JOHNS HOPKINS UNIVERSITY, BALTIMORE, April 8, 1878. 

 To the Editors of the Philosophical Magazine and Journal. 



GENTLEMEN: Some three years since, while in Berlin, I made some 

 experiments on the magnetic effect of electric convection, which have 

 since been published in the ' American Journal of Science ' for Jan- 

 uary, 1878. But previous to that, in 1876, Professor Helmholtz had 

 presented to the Berlin Academy an abstract of my paper, which has 

 been widely translated into many languages. But, although Helm- 

 holtz distinctly says, " Ich bemerke dabei, das derselbe den Plan f iir 

 seine (Rowland's) Versuche schon gefasst und vollstandig iiberlegt 

 hatte, als er in Berlin ankam, ohne vorausgehende Einwirkung von 

 meiner Seite," yet nevertheless I now find that the experiment is being 

 constantly referred to as Helmholtz's experiment and that if I get 

 any credit for it whatever, it is merely in the way of carrying out 

 Helmholtz's ideas, instead of all the credit for ideas, design of appar- 

 atus, the carrying out of the experiment, the calculation of results, and 

 everything which gives the experiment its value. 



Unfortunately for me, Helmholtz had already experimented on the 

 subject with negative results; and I found, in travelling through Ger- 

 many that others had done the same. The idea occurred in nearly 

 the same form to me eleven years ago; but as I recognized that the 

 experiment would be an extremely delicate one, I did not attempt it 

 until I could have every facility, which Helmholtz kindly gave me. 



Helmholtz kindly suggested a more simple form of commutator than 

 I was about to use, and also that I should extend my experiments so 

 as to include an uncoated glass disk as well as my gilded vulcanite 

 ones; but all else I claim as my own, the method of experiment in all 

 its details, the laboratory work, the method of calculation indeed every- 

 thing connected with the experiment in any way, as completely as if it had 

 been carried out in my own laboratory 4000 miles from the Berlin labor- 

 atory. Yours truly, H. A. ROWLAND. 



