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according action active spark antinodes apparatus appear assume axis bodies centimetres components constant copper wire deduced denote diameter dielectric difference direction disappear discharge dx dy dz dy dx effect electric force electric oscillations electrical disturbances electromagnetic force electromagnetic induction electromotive force electrostatic force end of book energy equal equations ether experiments finite further Hence Herr induction induction-coil insulated interference isotropic knobs latter length Leyden jars lines of force magnetic force magnitude Maxwell's equations Maxwell's theory metallic metres micrometer millimetres mirror motion neighbourhood nodes non-conductors number of lines observed obtained passive spark period of oscillation perpendicular phenomena phenomenon plane plate polarisation ponderomotive forces position primary conductor primary oscillation produced quantities reflection regard resonance rotation secondary circuit secondary conductor self-induction side space spark-gap spark-length sparking distance tion transversal waves true electricity tube variation velocity vertical wall wave-length waves in wires 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 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...
Page x - Natur uns unbegreiflich ist, erschaffen, so hat er auch können eine attractionem universalem materiae imprimiren, wenn gleich solche attractio supra captum ist, da hingegen die Principia Cartesiana allzeit contra captum etwas involviren." Here the writer, expressing wonder that Euler had so long adhered to the Cartesian principles, declares himself a thorough-going Newtonian, not merely in respect to gravitation versus vortices, but in believing that matter may have been created simply with the...
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 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 ix - Paris you see the universe composed of vortices of subtle matter ; at London we see nothing of the kind. With you it is the pressure of the moon which causes the tides of the sea; in England it is the sea which gravitates towards the moon. . . . You will observe also that the sun, which in France has nothing to do with the business, here comes in for a quarter of it. Among you Cartesians all is done by impulsion : with the Newtonians it is done by an attraction of which we know the cause no better...
Page xii - I saw him at work in the Royal Institution was in an underground cellar, which he had chosen for freedom from disturbance ; and he was arranging experiments to test the time of propagation of magnetic force from an electro-magnet through a distance of many yards of air to a fine steel needle polished to reflect light ; but no result came from those experiments. About the same time or soon after, certainly not long before the end of his working time, he was engaged (I believe at the shot tower near...
Page xv - rectilinear propagation," "polarisation," " reflection," "refraction," appearing in it as sub-titles. During the 56 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 x - ... impartiality, divided the prize between Cartesians and Newtonians. Thus in 1734, the question being, the cause of the inclination of the orbits of the planets, the prize was shared between John Bernoulli, whose Memoir was founded on the system of vortices, and his son Daniel, who was a Newtonian. The last act of homage of this kind to the Cartesian system was performed in 1740, when the prize on the question of the tides was distributed between Daniel Bernoulli, Euler, Maclaurin, and Cavallieri...
Page 20 - ... Maxwell's work, and, even when he has not stumbled upon unwonted mathematical difficulties, has nevertheless been compelled to abandon the hope of forming for himself an altogether consistent conception of Maxwell's ideas. I have fared no better myself. Notwithstanding the greatest admiration for Maxwell's mathematical conceptions, I have not always felt quite certain of having grasped the physical significance of his statements.