Chapter VI: Waves and Ripples in the æther

The experiments of Heinrich Hertz—Electric radiation—Lecture
apparatus for producing and detecting electric radiation—Electric
transparency and opacity—Why this difference—The reflection
of electric radiation—The refraction of electric rays—An
electric prism and an electric lens—The electric refractive
index—Interference of electric rays—The velocity of electric
radiations identical with that of light—Dark heat rays—Actinic
or photographic rays—The cause of colour—The frequency of
light waves—The classification of electric or æther waves—The
gamut of æther waves—The eye an æther-wave detector of limited
power—The electro-magnetic theory of light—Artificial production
of light—Use of Hertz waves in wireless telegraphy—Marconi’s
methods—Marconi’s aerial and wave-detector—The Morse
alphabet—How a wireless message is sent—The tuning of wireless
stations—Communication between ships and shore—The velocity of
wireless waves—Conclusion 232

APPENDIX 287

INDEX 293

USEFUL MEMORANDA.

One statute mile is 5280 feet.
One nautical mile is 6086 feet = 1¹⁄₆ statute mile.
A knot is a speed of 1 nautical mile per hour.

Hence the following rules:—

To convert
Knots to miles per hour—multiply by 1¹⁄₆.
Miles per hour to knots—multiply by ⁶⁄₇.
Feet per second to miles per hour—multiply by ²⁄₃. ⁄
Feet per second to knots—multiply by ⁶⁄₁₀.
Knots to feet per minute—multiply by 100.

WAVES AND RIPPLES IN WATER,
AIR, AND ÆTHER.

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