PRELIMINARY NOTICE 



THE present volume contains the memoirs 

 on the subject of " N " rays, communicated to 

 the Academy of Sciences by Prof. R. Blondlot. 

 The papers have been reprinted exactly as 

 they were originally published in the Comptes 

 Rendus of the Academy. The notes at the 

 end were added later, with the object of throw- 

 ing light on certain points which were obscure 

 at the time the papers were communicated to 

 the Academy. 



The title of the first memoir in this collec- 

 tion, "On the Polarization of ' X ' Rays," will 

 hardly cause astonishment when it is realized 

 that the study of the " X " rays led the author 

 to recognize the existence of radiations of a 

 totally different character. To these he gave 

 the name of " N " rays. Before the distinction 

 of these two kinds of radiation was made, 



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