NEAR the summit of the hill in the Quartier Montmartre, Paris, is a little street in which the grass grows between the paving-stones, as in the avenues of some dead old Italian city. Tall buildings border it for about one third its length, and the walls of tiny gardens, belonging to houses on adjacent streets, occupy the rest of its extent. It is a populous thoroughfare, but no wheels pass through it, for the very good reason that near the upper end it suddenly takes a short turn, and shoots up the hill at an incline too steep for a horse to climb.

This work is not presented to the reader as a treatise on astronomy, although the different phenomena pertaining to that splendid science are reviewed with some detail, and the established facts bearing upon the subjects discussed are briefly cited in the very words of the great writers upon whose authority they rest. A considerable experience in chemistry, electricity, and the other allied physical sciences long since convinced the author of this work that some simple and uniform principle must control the production of the physical phenomena of astronomy,—some general law capable of being extended in its application to the widest, as well as applied to the narrowest, limits of that science. Knowing the absolute certainty of a magnetic and electrical connection between the sun and the earth, as evidenced by the reflected energy of sun-spots, auroras, etc., and that no known cause except electricity could account for some, at least, of the cometic phenomena, it seemed that any comprehensive law must at all events include this mode of energy as an effective cause, and that if the law be uniform in its application, it must equally exclude all others which may be either antagonistic or not necessary.