"Maxwell's treatises, begun in 1861-62 and concluded in 1873 in his famous "Treatise on Electricity and Magnetism," as well as the brilliant experimental confirmation of Maxwell's results by H. Hertz from 1887, seemed calculated to deprive Weber's views of the last vestige of vitality. ...Maxwell's formulæ, wholly void as they were of atomistic conceptions, represented the fundamental electrical phenomena just as well as the old conceptions based upon action at a distance, and the newly-discovered Hertzian waves could only be represented by Maxwell's theory. ...this brilliant success had at first blinded physicists with regard to the insufficiency of Maxwell's theory in... optical phenomena. According to Maxwell... the vibrations of light were not mechanical, but electrical vibrations of the ether, and the two constants by which Maxwell defined the electric and magnetic behaviour of every body (the dielectric constant and the magnetic permeability) had also to be the determining elements in its refractive power. Although the condition demanded by Maxwell—of the refractive power varying as the square root of the dielectric constant—was well fulfilled in a number of bodies, yet... many bodies, notably water, showed... enormous deviations... To this was added the dependence of the refractive index upon the colour [frequency], for which the original theory gave no explanation whatever."