issot, whose brilliant studies have thrown
a bright light on different interesting points, such as the role of
the antennae. It would be equally impossible to pass over in silence
other recent attempts in a slightly different groove. Marconi's
system, however improved it may be to-day, has one grave defect. The
synchronism of the two pieces of apparatus, the transmitter and the
receiver, is not perfect, so that a message sent off by one station
may be captured by some other station. The fact that the phenomena of
resonance are not utilised, further prevents the quantity of energy
received by the receiver from being considerable, and hence the
effects reaped are very weak, so that the system remains somewhat
fitful and the communications are often disturbed by atmospheric
phenomena. Causes which render the air a momentary conductor, such as
electrical discharges, ionisation, etc., moreover naturally prevent
the waves from passing, the ether thus losing its elasticity.

Professor Ferdinand Braun of Strasburg has conceived the idea of
employing a mixed system, in which the earth and the water, which, as
we have seen, have often been utilised to conduct a current for
transmitting a signal, will serve as a sort of guide to the waves
themselves. The now well-known theory of the propagation of waves
guided by a conductor enables it to be foreseen that, according to
their periods, these waves will penetrate more or less deeply into the
natural medium, from which fact has been devised a method of
separating them according to their frequency. By applying this theory,
M. Braun has carried out, first in the fortifications of Strasburg,
and then between the island of Heligoland and the mainland,
experiments which have given remarkable results. We might mention also
the researches, in a somewhat analogous order of ideas, by an English
engineer, Mr Armstrong, by Dr Lee de Forest, and also by Professor
Fessenden.

Having thus arrived at the end of this long journey, which has taken
him from the first attempts down to the most recent experiments, the
historian can yet set up no other claim but that of having written the
commencement of a history which others must continue in the future.
Progress does not stop, and it is never permissible to say that an
invention has reached its final form.

Should the historian desire to give a conclusion to his labour and
answer the question the reader would doubtless not fail to put to him,
"To wh