THE N KAYS OF M. BLONDLOT. 



By C. G. Abbot. 



[The so-called "N rays," recently described by M. Blondlot and 

 others, have too respectable an introduction to the scientilic pul)lic in 

 the Comptes Rendus of the Institute of France (from which this paper 

 has l)een 'chiefly abstracted) and have attracted too wide attention to 

 justify an omission of all notice of them in this place. It never- 

 theless seems proper to state here that the experiments on which they 

 rest are not universally deemed conclusive, and that final judgment 

 upon them ma}' 1)e suspended until the appearance of still further 

 evidence. — Note by S. P. Langlev.] 



DISCOVERY. 



In the early part of the year 10(»3 M. Blondlot, professor of physics 

 at the University of Nancy, was carrying on some studies of the X 

 rays to discover if these could be polarized. He found that a con- 

 venient method of recognizing- the presence and possil)le polarization 

 of these rays consisted in the employment of a small electric spark- 

 ing device. Two sharpened wires, communicating inductively with 

 the terminals of a Kuhmkorff coil, were so nearly approached that 

 feeble sparks continually passed between them, and upon bringing 

 this sparking de^•ice near a source of X rays the luminosity of the 

 sparks was found to increase. M. Blondlot at first thought he 

 detected by his experiments a considerable degree of polarization in 

 the X rays, but a little later he decided that it was not the X ra3^s 

 themselves which gave the appearance of polarization, but a new kind 

 of rays heretofore unrecognized. In his first experiments with these 

 rays their source was a Crookes tube provided with a thin covering of 

 aluminum to cut off the light. The rays which traversed the aluminum 

 then passed through a ivctangular opening in a sheet of lead and fell 

 upon the little sparking device already mentioned. It was found that 

 only when the line of sparks Hew in a certiiin direction, as compared 

 with the slit in the leaden sheet, could the maxinuun brightness be 

 observed, and this direction for maximum brightn(\ss was altered Avhen 

 a substance which rotates the plane of polarization of light was intro- 

 duced. 



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