agitations of the stresses and strains. In this way an immense unification was effected of the various doctrines of light, heat, electricity, and energy, which now coalesced into the one science of the ether. The theory was gradualiy elaborated throughout the nineteenth century by a brilliant group of physicists and mathematicians, French, German, Dutch, Scandinavian, British, Italian, American. The details of their work, and the relative contributions of various individuals, are not to the point here.
The final result is that the activities of the ether are very different from any of the modes of activity which the common-sense analysis ascribes to ordinary matter. If the doctrine of ether be correct, then our ordinary notions of matter are derived from observations of certain average results which cloak the real nature oftheactivities of ether. The more recent revolution which has culminated in the physics of the present day has
