244 Intelligence and Miscellaneous Articles. 



their discoverer, and to the phenomena brought forward on Thursday 

 week at the Royal Society, and on the evening of the following day 

 at the Royal Institution, the lecturer proposes to apply the term 

 calorescence. 



It was the discovery, more than three years ago, of a substance 

 opake to light, and almost perfectly transparent to radiant heat — 

 a substance which cut the visible spectrum of the electric light sharply 

 off at the extremity of the red, and left the ultra-red radiation almost 

 untouched — that led the lecturer to the foregoing results. They lay 

 directly in the path of his investigation, and it was only the diversion 

 of his attention to subjects of more immediate interest, that prevented 

 him from reaching, much earlier, the point which he has now at- 

 tained. On this, however, the lecturer could found no claim, and 

 the idea of rendering ultra-red rays visible, though arrived at inde- 

 pendently, does not by right belong to him. The right to a scientific 

 idea or discovery is secured by the act of publication ; and, in virtue 

 of such an act, priority of conception as regards the conversion of 

 heat-rays into light-rays, belongs indisputably to Dr. Akin. At the 

 Meeting of the British Association, assembled at Newcastle in 1863, 

 he proposed three experiments, by which he intended to solve this 

 question. He afterwards became associated with an accomplished 

 man of science, Mr. Griffith, of Oxford, and jointly with him pur- 

 sued the inquiry. Two out of the three experiments proposed at 

 Newcastle are, the lecturer believed, impracticable ; but the third, 

 though not yet executed, may nevertheless be capable of execu- 

 tion. In that third Dr. Akin proposed to converge the rays of the 

 sun by a concave mirror, to cut off the light by " proper absorbents," 

 and to bring platinum-foil into the focus of invisible rays. It is 

 quite possible that, had he possessed the instrumental means at the 

 lecturer's disposal, or had he been sustained as the lecturer had been, 

 both by the Royal Society and the Royal Institution, Dr. Akin might 

 have been the first to effect the conversion of the dark heat-rays 

 into luminous ones. For many years the idea of forming an intense 

 focus of invisible rays had been perfectly clear before the lecturer's 

 mind, and in 1862 he published experiments upon the subject. He 

 had then discovered the properties of iodine, and had made use of 

 this substance as an absorbent, in the manner subsequently proposed 

 by Dr. Akin. The effects observed by him in 1862 at the focus of 

 invisible rays, were such as no previous experimenter had witnessed, 

 and no experimenter could have observed them without being driven 

 to the results which formed the subject of the evening's discourse. 

 Still publication is the sole test of scientific priority, and it cannot 

 be denied that Dr. Akin was the first to propose definitely to change 

 the refrangibility of the ultra-red rays of the spectrum, by causing 

 them to raise platinum-foil to incandescence. 



XXXV. Intelligence and Miscellaneous Articles. 



ON THE HEATING OF THE GLASS PLATE OF THE LEYDEN JAR BY 

 THE DISCHARGE. BY DR. WERNER SIEMENS. 



A S it seemed probable to me that the glass plate of the Leyden jar 

 -£*■ must be heated by the charge and discharge, I arranged an ap- 



