passed, or, as it were, leaped, these respective intervals of space in the same time. We look back, let me here remark, upon the incredible dulness of the nineteenth-century mind, which was unable to catch many a subsequent discovery, although such discovery rested mainly upon proportions of which the elements or factors were, in certain instances, already well ascertained—such as the cases of the comparative wave dimensions of sound and light, which are long ago amongst our basal facts for so much of modern knowledge and discovery; for, on ascertaining, for instance, electro-light speed, we are able, and at once, to infer the distance separating the ether points, or particles; while that inference, by a further inference, in curious backward process, gave us the separating distance between ordinary material atoms, and the dimensions and mass of these themselves: this latter very remarkable inference being, however, of the less consequence at the time, as we had already arrived, by another and independent process, at the separating distances, the mass and the form of these elementary bodies.
By this great discovery of cross-electric speed, we were enabled to despatch the electro-light motor into far-off space, to overtake the ordinary light on its image or picture-carrying mission. It was not, however, until the further discovery of the Duplication of the Cross-Electric that we could bring back the overtaken picture—as, for instance, that of our little earth, as it was when the light quitted it so many years or so many ages past. Indeed, the vastly greater speed thus attained made us at last regard, with something like contempt, the old ordinary light-speed of about
