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according action active spark antinodes appear axis Bibliography bodies centimetres Clothbound constant copper wire denote direction disappear discharge dx dy dy dz effect electric force electric waves electromagnetic force electromagnetic induction electromotive force electrostatic force end of book energy equal equations ether experiments figures finite Helmholtz Hence Herr Index induction induction-coil insulated interference knobs latter length Leyden jars light lines of force LISTEN & LEARN magnetic force magnitude mathematical Maxwell Maxwell's equations Maxwell's theory mechanical metallic metres micrometer millimetres mirror motion neighbourhood nodes non-conductors observed obtained optical paper Paperbound passive spark period of oscillation perpendicular phenomena phenomenon plane plate polarisation position potential primary conductor primary oscillation produced propagation reflection regard resonance rotation secondary circuit secondary conductor side space spark-gap spark-length sparking distance tion transversal waves true electricity tube variation velocity vibration wall wave-length wire zero
Page xi - That gravity should be innate, inherent and essential to matter, so that one body may act upon another at a distance through a vacuum, without the mediation of any thing else, by and through which their action and force may be conveyed from one to another, is to me so great an absurdity, that I believe no man who has in philosophical matters a competent faculty of thinking, can ever fall into it.
Page x - Here the writer, expressing wonder that Euler had so long adhered to the Cartesian principles, declares himself a thoroughgoing Newtonian, not merely in respect to gravitation versus vortices, but in believing that matter may have been created simply with the law of universal attraction without the aid of any gravific medium or mechanism. But in this he was more Newtonian than Newton himself. Indeed Newton was not a Newtonian, according to Daniel Bernoulli's idea of Newtonianism, for in his letter...
Page xiv - ... it would appear that the transfer of a single spark is sufficient to disturb perceptibly the electricity of space throughout at least a cube of 400,000 feet of capacity ; and when it is considered that the magnetism of the needle is the result of the difference of two actions, it may be further inferred that the diffusion of motion in this case is almost comparable with that of a spark from a flint and steel in the case of light.
Page 21 - The geometrical and the logical place agree in that each is the possibility of an existence." (TLP 3. 411.) shorter or more definite answer than the following: Maxwell's theory is Maxwell's system of equations. Every theory which leads to the same system of equations, and therefore comprises the same possible phenomena, I would consider as being a form or special case of Maxwell's theory; every theory which leads to different equations, and therefore to different possible phenomena, is a different...
Page iii - Is. 6d. ELECTRIC WAVES : Being Researches on the Propagation of Electric Action with Finite Velocity through Space. By Dr. Heinrich Hertz. Translated by DE Jones. 10s. 6d.
Page 28 - If we wish to lend more colour to the theory, there is nothing to prevent us from supplementing all this and aiding our powers of imagination by concrete representations of the various conceptions as to the nature of electric polarisation, the electric current, etc. But scientific accuracy requires of us that we should in no wise confuse the simple and homely figure, as it is presented to us by nature, with the gay garment which we use to clothe it.
Page xv - rectilinear propagation," " polarization," " reflection," " refraction," appearing in it as subtitles. During the fifty-six years which have passed since Faraday first offended physical mathematicians with his curved lines of force, many workers and many thinkers have helped to build up the nineteenth century school of plenum...
Page 200 - Again, the incompleteness of form referred to renders it more difficult to apply Maxwell's theory to special cases. In. connection with such applications I have been led to endeavour for some time past to sift Maxwell's formulae and to separate their essential significance from the particular form in which they first happened to appear.
Page 154 - ... horse-power. The primary oscillator must be supplied with energy at fully this rate if its oscillations are to be kept up continuously and with constant intensity in spite of the radiation. During the first few oscillations the intensity of the radiation at a distance of about 12 metres from the primary conductor corresponds to the intensity of the sun's radiation at the surface of the earth.
Page xii - Faraday, with his curved lines of electric force, and his dielectric efficiency of air and of liquid and solid insulators, resuscitated the idea of a medium through which, and not only through which but by which, forces of attraction or repulsion, seemingly acting at a distance, are transmitted. The long struggle of the first half of the eighteenth century was not merely on the question of a medium to serve for gravific mechanism, but on the correctness of the Newtonian law of gravitation as a matter...