non as an
indicator in the study of the Hertzian waves seems to have occurred
simultaneously to several physicists, among whom should be especially
mentioned M. Ed. Branly himself, Sir Oliver Lodge, and MM. Le Royer
and Van Beschem, and its use in laboratories rapidly became quite
common.

The action of the waves on metallic powders has, however, remained
some what mysterious; for ten years it has been the subject of
important researches by Professor Lodge, M. Branly, and a very great
number of the most distinguished physicists. It is impossible to
notice here all these researches, but from a recent and very
interesting work of M. Blanc, it would seem that the phenomenon is
allied to that of ionisation.

Sec. 8

The history of wireless telegraphy does not end with the first
experiments of Marconi; but from the moment their success was
announced in the public press, the question left the domain of pure
science to enter into that of commerce. The historian's task here
becomes different, but even more delicate; and he will encounter
difficulties which can be only known to one about to write the history
of a commercial invention.

The actual improvements effected in the system are kept secret by the
rival companies, and the most important results are patriotically left
in darkness by the learned officers who operate discreetly in view of
the national defence. Meanwhile, men of business desirous of bringing
out a company proclaim, with great nourish of advertisements, that
they are about to exploit a process superior to all others.

On this slippery ground the impartial historian must nevertheless
venture; and he may not refuse to relate the progress accomplished,
which is considerable. Therefore, after having described the
experiments carried out for nearly ten years by Marconi himself, first
across the Bristol Channel, then at Spezzia, between the coast and the
ironclad _San Bartolommeo_, and finally by means of gigantic apparatus
between America and England, he must give the names of those who, in
the different civilised countries, have contributed to the improvement
of the system of communication by waves; while he must describe what
precious services this system has already rendered to the art of war,
and happily also to peaceful navigation.

From the point of view of the theory of the phenomena, very remarkable
results have been obtained by various physicists, among whom should be
particularly mentioned M. T