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LETTER Ili.

Of the Solar System, and the Firmament

OF THE FIXED STARS.

A S the figure and motion of the earth arfe* ^ now sufficiently established, it will be pro-per to turn our attention to the rest of theplanets ; and, from describing their nature andproperties, to exhibit a summary view of thewhole system. In the first place, then, it is tobe observed, that the planets are all Opaquespherical bodies, like our. earth, that have noproper light of their own, but fliine by meansof the borrowed light which they receive fromthe fun : for it is well known, from telescopicalobservations, that only that side of them whichis turned towards the fun is ever illuminated jwhilst the opposite side, which the borrowedrays cannot reach, remains continually dark andobscure.

And the planets are not only similar to ourearth in form and structure, but they likewiseperform their revolutions exactly in the famemanner. From the regular appearance anddisappearance of several remarkable dark spots,D a which,