IN astronomical text-books and popular works on the science one frequently, and naturally, meets with references to the enormously swift motions of celestial bodies, as compared with terrestrial experience. We read of the great comet of 1882 "rushing through the part of its orbit closest to the Sun," and the fixed stars are described as in reality "flying through space" at enormous velocities of varying direction and amount. One recalls how, in old schoolday s, when "doing globes," the master

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... uld ask the question, "How fast is the Earth moving in its orbit?" and the pupil would Itnswer, "Rather more than sixty thousand miles an hour."