It has been long known, both from theory and in practice, that the imperfect transparency of the earth’s atmosphere, and the unequal refraction which arises from differences of temperature, combine to set a limit to the use of high magnifying powers in our telescopes. Hitherto, however, the application of such high powers was checked by the imperfections of the instruments themselves; and it is only since the construction of Lord Rosse’s telescope that astronomers have found that, in our damp and variable climate, it is only during a few days of the year that telescopes of such magnitude can use successfully the high magnifying powers which they are capable of bearing. Even in a cloudless sky, when the stars are sparkling in the firmament, the astronomer is baffled by influences which are invisible, and while new planets and new satellites are being discovered by instruments comparatively small, the gigantic Polyphemus lies slumbering in his cave, blinded by thermal currents, more irresistible than the firebrand of Ulysses. As the astronomer, however, can not command a tempest to clear his atmosphere, nor a thunder storm to purify it, his only alternative is to remove his telescope to some southern climate, where no clouds disturb the serenity of the firmament, and no changes of temperature distract the emanations of the stars. A fact has been recently mentioned, which entitles us to anticipate great results from such a measure. The Marquis of Ormonde is said to have seen from Mount Etna, with his naked eye, the satellites of Jupiter. If this be true, what discoveries may we not expect, even in Europe, from a large reflector working above the grosser strata of our atmosphere. This noble experiment of sending a large reflector to a southern climate has been but once made in the history of science. Sir John Herschel transported his telescopes and his family to the south of Africa, and during a voluntary exile of four years’ duration he enriched astronomy with many splendid discoveries.—_Sir David Brewster_. MONTHLY RECORD OF CURRENT EVENTS.