The Ether of Space

THEORY

nd hence the name "luminiferous" was applied to it; though at the present day

can, concerning the properties of the Inte

distance equal to seven times the circumference of the earth every second; from New York to London and back in the thirtieth part of a second; and taking only eight minutes on the journey from the sun to the earth. This propagation in time of an undulatory disturbanc

medium must be a special kind of substance; and it is called the ether. The luminiferous ether it used to be called, because the conveyance of light was all it was then known to be capable of; but now that it is known to do a variety

hing heaving up and down, or perhaps of something breaking on a shore. But if you ask a mathematician what he means by a wave

= (v2) d

e simple

sin (x

bly refuse to give

nt in ordinary words, he is entirely justified; that is what is mea

"a disturbance periodic both in space and time." Anything thus doubly periodic is a wave; and all waves-whether in air as

overshoot the mark and oscillate beyond its place of equilibrium to and fro. Any medium possessing these two properties can transmit waves, and unless a medium possesses these properties in some form or other, or some equivalent for them, it may be said with moderate security to be incomp

t driving force,-power to rush uphill. Both causes together make it swing to and fro till its energy is exhausted. This is a disturbance simply periodic in time. A regular series of such springs, set at equal intervals and started vibrating at regular intervals of time one after the other, would be periodic in space too; and so they would, in disconnected fashion, typify a

esponds to the elastic displacement and recoil of the spring or pendulum? What corresponds to the

reiterated and insisted on by experiments performe

ponds to electrostatic charge,-

corresponds

the modern electromag

is statement, by reviewing some fundamental el

analogous to the drawing aside of our flexible spring. It is making use of the elasticity of the ether to produce a tendency to recoil. Letting go the

nts of electrostatics ethe

inetic energy? The most direct way would be, to take a stream of water and try suddenly to stop it. Open a water tap freely and then suddenly shut it. The impetus or momentum of

arrangement for developing powerful magnetism, and then suddenly stop the current by breaking the circuit. A violent flash occurs, if the stoppage is sudden enough, a flas

electromagnetic experiments illus

oot the mark, and for an instant the charge of the jar is reversed; the current now flows backwards and charges the jar up as at first; back again flows the current; and so on, charging and reversin

e ether possesses the two properties requisite for the generation and transmission of waves, viz.: elasticity, and inertia or density; hence

the spark indeed-but that is a mere secondary disturbance we can for the present ignore-I do not mean any secondary disturbance. I mean the true etherial waves emitted by the electric oscillation going on in the neighb

y are too slow. The vibrations set up when this large jar is discharged are from a hundred thousand to a million per second, but that is too slow for the retina. It responds only to vibrations between 400 billion and 700 billion per second. The vibrations are too quick for the ear, which responds only to vibrations between 40 and 40,000 per second. Between the highest audible and the lowest visible vib

in 1889 were 125 per second, and for some way above this the sparks emit a musical note; but no one has yet succeeded

imes a second, and emits etherial waves a yard long. The whole range of vibratio

to get a series of beautifully regular and gradually damped electric oscillations, with a per

or them. The great though simple discovery by Hertz, in 1888, of an "electric eye," as Lord Kelvin called it, made experiments on these waves for the first time easy or even possibl

n the basis of this discovery, the 'coherer' was employed by me for distant signalling by means of electric or

a large lens of pitch, weighing over three hundredweight, for concentrating them to a focus.[1] They can be made to show the phenomenon of interference, and thus have their wave-length accurately measured. They are stopped by all conducto

heory of light, and these electrically produced waves only illustrate and bring home the w

and for the first time we have a true theory of light,-no longer based upon analogy with sound, nor upon the supposed properties of some hypothetical

ding problems in optics are being rapidly solved, now that we have the means of definitely excit

tion. Smaller oscillators must be used-very much smaller-oscillators not much bigger than molecules. In all probability-one may almost say certainly-ordinar

n, will have most important practical consequences; and that matter is initially dealt with in a section on the Manufacture of Light,