outside France--Gutton and Mascart's confirmation--
Negative experiments prove nothing--Supposed
wave-length of N-rays.

§ 6. The Ether and Gravitation: Descartes'
and Newton's ideas on gravitation--Its speed and
other extraordinary characteristics--Lesage's
hypothesis--Crémieux' experiments with drops of
liquids--Hypothesis of ether insufficient.


CHAPTER VII

WIRELESS TELEGRAPHY

§ 1. Histories of wireless telegraphy already written,
and difficulties of the subject.

§ 2. Two systems: that which uses the material media (earth,
air, or water), and that which employs ether only.

§ 3. Use of earth as return wire by Steinheil
--Morse's experiments with water of canal--Seine used as
return wire during siege of Paris--Johnson and Melhuish's
Indian experiments--Preece's telegraph over Bristol
Channel--He welcomes Marconi.

§ 4. Early attempts at transmission of messages through
ether--Experiments of Rathenau and others.