ISect. i. Of, the SOLAR SYSTEM, 7

I Motion. For by this Rotation each Pointlof their Surfaces is carried successively to-Iwards or from the Sun, who always illu-tninates the Hemisphere which is next to[him, the other remaining obscure: And[while any Place is in the Hemisphere illu-minated by the Sun, it is Day j but whenit is carried to the obscure Hemisphere, it ■becomes Night ; and so continues until bythis Rotation the said Place is again en-?lightned by the Sun.

The Earth performs its Revolutionround its Axis in 23 Hours 56 Minutes the@&,Venus in 23 Hours; Mars in 24 Hours ^ a:idand 40 Minutes j and "Jupiter moves roundhis own Axis in o Hours and c6 Minutes. ??. an tThe Sun also is found to turn round his turn round.Axis from West to East in 27 Days; andthe Moon, which is nearest to us as all thePlanets, revolves about her Axis in a Month,or in the same Space of Time that ssie turnsround the Earth; so that the Lunarians havebut one Day throughout the Year.

I. The Planets are all Opaque Bodies,having no Light but what they borrow opaquefrom the Sun: For that Side of them which t”i a £ lo ‘is next towards the Sun has always beenobserved to be illuminated, in what Positionsoever they be; but the opposite Side, whichthe Solar Rays do not reach, remains darkand obscure: Whence it is evident, that theyhave no Light but what proceeds from theL 4 Sun;