226 Prof. Tyndall on the History of Calorescence. 



sciousness at the time that such an engagement existed, and that 

 anger now supplies him with a power of memory which in his 

 calmer moments he did not enjoy. 



I went to Switzerland early in July, and from Pontresina 

 wrote to my assistant, describing the apparatus I had intended 

 to employ, and desiring him to have it prepared for me. One 

 portion of it consisted simply of the substitution of a rock-salt 

 lens for the glass one of the electric lamp, and a rock-salt cell 

 for the glass one that I had used in 1862. With this arrange- 

 ment I executed the experiments "on luminous and obscure 

 radiation " described in the November Number of the Philoso- 

 phical Magazine. Nay, abandoning the rock-salt altogether, 

 and employing a glass lens of somewhat shorter focus than that 

 made use of in 1862, with a battery of sixty cells, I obtained 

 all the results with the electric lamp there described. In not 

 the slightest particular does this arrangement differ from that 

 which I had employed two years and three-quarters previously. 

 We have the same source of rays, the same mode of conver- 

 gence, and the same absorbent to intercept the luminous por- 

 tion of the radiation. And yet it is from this, my own ground, 

 which I had taken up practically before he had perused the 

 " little German treatise which first taught him what had been 

 done w on the subject of fluorescence, that Dr. Akin would fence 

 me out. 



Experiments on combustion could not decide the question of 

 ray-transmutation. "Intimately connected" they assuredly 

 were, — so intimately, indeed, that the man who could neglect to 

 pass immediately from the one to the other, would be unfit for 

 the vocation of a natural philosopher. Was I, then, out of con- 

 sideration for Dr. Akin, to keep my platinum-foil or my silver- 

 leaf away from the focus of dark rays, lest it should become in- 

 candescent there ? My duty to science ruled otherwise ; and 

 as no bond or promise existed to contravene that duty, I resolved 

 not to let the autumn pass as Dr. Akin had the summer, without 

 making some attempt to realize my ideas. He had already tried, 

 failed, and announced his failure. Still, however, wishing to 

 treat him with the utmost consideration, I resolved, while for- 

 warding the work of science, to leave the chance of prior publica- 

 tion open to Dr. Akin. I determined to hold back whatever 

 results I might obtain until he would be either able to precede 

 me, or could so far merge his individual interests in the larger 

 interests of science, as to be willing to see the results published. 

 This he deems an unusual proceeding on my part, and so it as- 

 suredly was. But from first to last my proceeding towards him 

 was unusual. In relation to any other man it would have been 



