The electron, its isolation and measurement and the determination of some of its properties — John Stuart Mill — John Shaqi
The electron, its isolation and measurement and the determination of some of its properties
John Stuart Mill · en
But striking and significant as were these discoveries, they did not
serve at all to establish the atomic hypothesis of the nature of
electricity. They were made at the very time when attention began to
be directed strongly away from the conception of electricity as a
substance of any kind, and it was no other than Faraday himself who, in
spite of the brilliant discoveries just mentioned, started this second
period in the development of electrical theory, a period lasting from
1840 to about 1900. In this period electrical phenomena are almost
exclusively thought of in terms of stresses and strains in the medium
which surrounds the electrified body. Up to this time a more or less
definite something called a charge of electricity had been thought of
as existing on a charged body and had been imagined to exert forces on
other charged bodies at a distance from it in quite the same way in
which the gravitational force of the earth acts on the moon or that of
the sun on the earth. This notion of action at a distance was repugnant
to Faraday, and he found in the case of electrical forces experimental
reasons for discarding it which had not then, nor have they as yet,
been found in the case of gravitational forces. These reasons are
summed up in the statement that the electrical force between two
charged bodies is found to depend on the nature of the intervening
medium, while gravitational pulls are, so far as is known, independent
of intervening bodies. Faraday, therefore, pictured to himself the
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intervening medium as transmitting electrical force in quite the same
way in which an elastic deformation started at one end of a rod is
transmitted by the rod. Further, since electrical forces act through a
vacuum, Faraday had to assume that it is the ether which acts as the
transmitter of these electrical stresses and strains. The properties
of the ether were then conceived of as modified by the presence of
matter in order to account for the fact that the same two charges
attract each other with different forces according as the intervening
medium is, for example, glass, or ebonite, or air, or merely ether.
These views, conceived by Faraday and put into mathematical form by
Maxwell, called attention away from the electrical phenomena in or
on a conductor carrying electricity and focused it upon the stresses
and strains taking place in the medium about the conductor. When in
1886 Heinrich Hertz in Bonn, Germany, proved by direct experiment
that electrical forces are indeed transmitted in the form of electric
waves, which travel through space with the speed of light exactly
as the Faraday-Maxwell theory had predicted, the triumph of the
ether-stress point of view was complete. Thereupon textbooks were
written by enthusiastic, but none too cautious, physicists in which it
was asserted that an electric charge is nothing more than a “state of
strain in the ether,” and an electric current, instead of representing