M. Gutton and a note by M. Mascart have
reanimated the confidence of those who hoped that such a scholar as M.
Blondlot could not have been deluded by appearances. However, these
last proofs in favour of the existence of the rays have themselves
been contested, and have not succeeded in bringing conviction to
everyone.

It seems very probable indeed that certain of the most singular
conclusions arrived at by certain authors on the subject will lapse
into deserved oblivion. But negative experiments prove nothing in a
case like this, and the fact that most experimenters have failed where
M. Blondlot and his pupils have succeeded may constitute a
presumption, but cannot be regarded as a demonstrative argument. Hence
we must still wait; it is exceedingly possible that the illustrious
physicist of Nancy may succeed in discovering objective actions of the
N rays which shall be indisputable, and may thus establish on a firm
basis a discovery worthy of those others which have made his name so
justly celebrated.

According to M. Blondlot the N rays can be polarised, refracted, and
dispersed, while they have wavelengths comprised within .0030 micron,
and .0760 micron--that is to say, between an eighth and a fifth of
that found for the extreme ultra-violet rays. They might be, perhaps,
simply rays of a very short period. Their existence, stripped of the
parasitical and somewhat singular properties sought to be attributed
to them, would thus appear natural enough. It would, moreover, be
extremely important, and lead, no doubt, to most curious applications;
it can be conceived, in fact, that such rays might serve to reveal
what occurs in those portions of matter whose too minute dimensions
escape microscopic examination on account of the phenomena of
diffraction.

From whatever point of view we look at it, and whatever may be the
fate of the discovery, the history of the N rays is particularly
instructive, and must give food for reflection to those interested in
questions of scientific methods.

Sec. 6. THE ETHER AND GRAVITATION

The striking success of the hypothesis of the ether in optics has, in
our own days, strengthened the hope of being able to explain, by an
analogous representation, the action of gravitation.

For a long time, philosophers who rejected the idea that ponderability
is a primary and essential quality of all bodies have sought to reduce
their weight to pressures exercised in a very subtle fluid. This