precautions, and the constancy of the results is an absolute guarantee of their worth.
From my communication of May 11, 1903, and from what precedes, it is clear that, from the beginning of my researches on "N" rays, I had succeeded in recording their action on the spark by an objective method.
On a New Species of "N" Rays (February 29, 1904).
Observations made during a very complex experiment, which I owe to Dr. Th. Guidloz, led me to suspect the existence of a variety of "N" rays, which, instead of increasing, on the contrary, diminished the glow of a feeble luminous source. I undertook to search for rays of this type amongst those emitted by a Nernst lamp. While previously studying the spectrum of this emission, produced by an aluminium prism, I had not met with such radiations. I consequently thought that there were reasons for studying anew, and still more minutely, the feebly deviated part of the spectrum. On
