9 of 1906), pp.

677 _et seq._, which seem conclusive on this point .-- ED.] I must here leave out the description of a crowd of other experiments.
Some very interesting researches by M.Brunhes, M.Broca, M.
Colardeau, M.Villard, in France, and by many others abroad, have permitted the elucidation of several interesting problems relative to the duration of the emission or to the best disposition to be adopted for the production of the rays.

The only point which will detain us is the important question as to the nature of the X rays themselves; the properties which have just been brought to mind are those which appear essential and which every theory must reckon with.
The most natural hypothesis would be to consider the rays as ultra-violet radiations of very short wave-length, or radiations which are in a manner ultra-ultra-violet.

This interpretation can still, at this present moment, be maintained, and the researches of MM.

Buisson, Righi, Lenard, and Merrit Stewart have even established that rays of very short wave-lengths produce on metallic conductors, from the point of view of electrical phenomena, effects quite analogous to those of the X rays.