om, in short, should the invention of wireless telegraphy more
particularly be attributed?" he should certainly first give the name
of Hertz, the genius who discovered the waves, then that of Marconi,
who was the first to transmit signals by the use of Hertzian
undulations, and should add those of the scholars who, like Morse,
Popoff, Sir W. Preece, Lodge, and, above all, Branly, have devised the
arrangements necessary for their transmission. But he might then
recall what Voltaire wrote in the _Philosophical Dictionary_:

"What! We wish to know what was the exact theology of Thot, of
Zerdust, of Sanchuniathon, of the first Brahmins, and we are ignorant
of the inventor of the shuttle! The first weaver, the first mason, the
first smith, were no doubt great geniuses, but they were disregarded.
Why? Because none of them invented a perfected art. The one who
hollowed out an oak to cross a river never made a galley; those who
piled up rough stones with girders of wood did not plan the Pyramids.
Everything is made by degrees and the glory belongs to no one."

To-day, more than ever, the words of Voltaire are true: science
becomes more and more impersonal, and she teaches us that progress is
nearly always due to the united efforts of a crowd of workers, and is
thus the best school of social solidarity.

CHAPTER VIII

THE CONDUCTIVITY OF GASES AND THE IONS

Sec. 1. THE CONDUCTIVITY OF GASES

If we were confined to the facts I have set forth above, we might
conclude that two classes of phenomena are to-day being interpreted
with increasing correctness in spite of the few difficulties which
have been pointed out. The hypothesis of the molecular constitution of
matter enables us to group together one of these classes, and the
hypothesis of the ether leads us to co-ordinate the other.

But these two classes of phenomena cannot be considered independent of
each other. Relations evidently exist between matter and the ether,
which manifest themselves in many cases accessible to experiment, and
the search for these relations appears to be the paramount problem the
physicist should set himself. The question has, for a long time, been
attacked on various sides, but the recent discoveries in the
conductivity of gases, of the radioactive substances, and of the
cathode and similar rays, have allowed us of late years to regard it
in a new light. Without wishing to set out here in detail facts which
for the most part are well k