Mars too is found not to be without his dark Spots, by means of which he has been obſerved to turn round his own Axis in 24 Hours and 40 Minutes; the Length of his Day: but whether he has Clouds or no, we have not had the ſame opportunity of obſerving as in Jupiter, as well becauſe even when he is neareſt the Earth, he appears to us much leſs than Jupiter, as that his Light not coming ſo far, is ſo brisk as to be an Impediment to exact Obſervations: And this Reaſon is as much ſtronger in Venus as its Light is. But ſince ’tis certain that the Earth and Jupiter have their Water and Clouds, there is no Reaſon why the other Planets [But not juſt like ours.] ſhould be without them. I can’t ſay that they are exactly of the ſame nature with our Water; but that they ſhould be liquid their Uſe requires, as their Beauty does that they ſhould be clear. For this Water of ours, in Jupiter or Saturn, would be frozen up inſtantly by reaſon of the vaſt diſtance of the Sun. Every Planet therefore muſt have its Waters of ſuch a temper, as to be proportioned to its Heat: Jupiter’s and Saturn’s muſt be of ſuch a Nature as not to be liable to Froſt; and Venus’s and Mercury’s of ſuch, as not to be eaſily evaporated by the Sun. But in all of them, for a continual ſupply of Moiſture, whatever Water is drawn up by the Heat of the Sun into Vapours, muſt neceſſarily return back again thither. And this it cannot do but in Drops, which are cauſed as well there as with us, by their aſcending into a higher and colder Region of the Air, out of that which, by reaſon of the Reflection of the Rays of the Sun from the Earth, is warmer and more temperate.