tion were largely
anticipated by us. The tuning of wireless messages by which the
interception of messages is prevented was certainly forestalled by us,
though in the communications with Mars herein detailed the ordinary
[_non-syntonic_.--Editor] receiver was employed.

We employed an induction coil, emitted a wave by a spark, and had a wire
rod [_antenna_.--Editor] which was in turn part of an induction coil.
This was the sender (transmitter) and we could regulate the wave length
so that a receiving wire adjusted for such a wave could only receive it.
[There seems to be implied in these words an arrangement known as the
Slaby-Arco system, which American readers have had described for them by
M.A. Frederick, Collins, Sci. Amer., March 9 and Dec. 28,
1901.--Editor.] The receiver consisted of iron filings in which later
carbon particles were added.

My father died in 1892 and we had not at the time of his death learned
of Popoff's microphone-coherer in which steel filings were mixed with
carbon granules. The magnetic waves received at first by us presumably
from Mars, and later, as the communications indisputably show, from that
planet, were taken upon a Marconi receiver, or what was practically
that.

My father became more and more interested in the direction of
interplanetary research by means of the magnetic wave. He argued
vehemently, buoyed up by his increasingly augmented hopes as our own
experiments improved, that the electric wave through space moving in an
ethereal fluid of the extremest purity would progress more rapidly than
in our atmosphere, that the tension of such waves would be greater, that
they could be so "heaped up" as he expressed it--(_In the Slaby-Arco
system an apparatus is employed consisting of a Ruhmkorff coil with a
centrifugal mercury interrupter, by which a steeper wave front of the
disruptive discharge is secured_.--Editor)--that their reception over
the almost impassable distances of space would be made possible.

This idea of piling up the waves was suggested by purely physical
analogies. The enormous waves generated by severe storms upon the ocean
travel farther than the smaller waves, and are less consecutively
dissipated by the resistance of the water, the traction of its molecules
and the occasional diversion of cross disturbances from other centers.

Again some experiments made invacuo upon a limited scale seemed to show
the accuracy of his predictions. Through a glass tube one f