Force Propagation Research Articles

Velocity of Propagation of Electrostatic Force

LORD KELVIN, in his letter published in NATURE, February 6, says that “it is an abuse of words to speak of the ‘elastic solid theory of electricity and magnetism’ when no one has hitherto shown how to find in an elastic solid anything analogous to the attraction between rubbed sealing-wax and a little fragment of paper … or between two wires conveying electric currents.”

Velocity of Propagation of Electrostatic Force

DR. BOTTOMLEY'S note published in NATURE of January 23, quotes an extract from my Baltimore Lectures of October 1884, in which this subject is spoken of, with an illustration consisting of two metal spheres at a great distance asunder, having periodically varying opposite electrifications maintained in them by a wire connecting them through an alternate current dynamo.

Forthcoming Scientific Books

AMONG Messrs. MACMILLAN AND CO's announcements are the following books:—“Evolution and Man's Place in Nature,” by Prof. H. Calderwood; “A Primer of Practical Horticulture,” by J. Wright; “A Text-book of Tropical Agriculture,” by H. A. Nicholls, M.D., F.L.S., C.M.Z.S., with illustrations; “The Food of Plants,” by A. P. Laurie; “Metal Colouring and Bronzing,” by Arthur H. Hiorns; “Differential Calculus for Schools,” by Joseph Edwards; “The Beauties of Nature: and the Wonders of the World we live in.” by the Right Hon. Sir John Lubbock, Bart., M.P., F.R.S., with illustrations; “Finger Prints,” by Francis Galton, F.R.S., with numerous illustrations; “Hereditary Genius: an Inquiry into its Laws and Consequences,” by Francis Galton, F.R.S., new edition; “Materials for the Study of Variation in Animals,” Part I., discontinuous variation, by William Bateson, illustrated; “On Colour Blindness,” by Thomas H. Bickerton, illustrated (NATURE series); Hygiene: its Principles as applied to Public Health, adapted to the requirements of the Elementary and Advanced Stages of the Science and Art Department, &c,” by Edward F. Willoughby, M.B., new and enlarged edition; “A Uniform Edition of Prof. Huxley's Essays, Uniform with the works of Emerson, John Morley, &c., in 6 vols., comprising Lay Sermons, Addresses and Reviews, Critiques and Addresses, Science and Culture, American Addresses, Man's Place in Nature,” &c.; “Atlas of Classical Antiquities,” by Th. Schreiber, edited for English use by Prof. W. C. F. Anderson; “Researches on the Propagation of Electrical Force,” by Prof. Henrich Hertz, authorized translation by Prof. D. E. Jones, B.Sc., illustrated; “A Text-book of Pathology: Systematic and Practical,” by Prof. D. J. Hamilton; “Electrical Papers,” by Oliver Heaviside; “Pioneers of Science,” by Prof. Oliver Lodge, with portraits and other illustrations; “The Diseases of Modern Life,” by B. W. Richardson, M.D., new and cheaper edition; “The Theory and Practice of Absolute Measurements in Electricity and Magnetism,” by Prof. A. Gray, Vol. II., and “A Theory of Wages and its Application to the Eight Hours Question and the Labour Problems,” by Herbert M. Thompson.

Action at a distance, and the transmission of stress by isotropic elastio solid media

The mutual action of two electrified bodies was regarded by Maxwell as transmitted by a medium. According to him the stress in the medium consists of a “tension like a rope” along the lines of electrical force whose intensity per unit of area is R2/8π, where R is the resultant electric intensity, and of a pressure numerically equal to this in all orthogonal directions. Maxwell's remarks are somewhat vague but his notation is strongly suggestive of an elastic solid medium. It has, however, been pointed out by Minchin that Maxwell's stress system would not in an ordinary elastic solid give origin to strains consistent with the “equations of compatibility” which the theory of elastic solids supplies. Considerable interest still attaches to the theory of an elastic solid medium propagating stresses equivalent to the action between distant bodies of forces varying inversely as the square of the distance. For in the first place, it has been pointed out that the stress system given by Maxwell does not constitute a unique solution of his equations; and, in the second place, it has been suggested that some medium must exist for the transmission of gravitational forces. The statical problem of the propagation of gravitational forces by an isotropic elastic medium has been treated by Minchin. His treatment how ever neglects a certain surface condition. I have thus thought it worth while to consider the problem independently, employing the ordinary surface conditions. The first part of the paper is devoted more especially to the electrostatic problem, but the elastic solid problem is essentially the same throughout.

The Forces of Electric Oscillations Treated According to Maxwells Theory. by Dr. H. Hertz: 1

III. The Interference Experiments. IN order to ascertain the velocity of propagation of electric force in the equatorial plane, we brought it into interference with another wave advancing with corresponding constant velocity in a wire. The result was, that the successive interferences did not occur at equal distances, but followed more rapidly in the neighbourhood of the oscillator than at greater distances.

XXXIV.—On the direction and mode of propagation of the electric force traversing interposed media

XXXIV.—<i>On the direction and mode of propagation of the electric force traversing interposed media</i>