It will be obvious also to any one, that the inhabitants of the sun _cannot see_ any heavenly body, as the stars, and planets; because they are inclosed by those clouds, which are impenetrable to vision. They may catch a glimpse of a passing star through these openings as we do of the sun’s body. It is highly probable (see _our_ paper on light, attached to our author’s chapter on the same,) that these luminous phosphoric clouds _do not actually emit light, or heat_; but only _excite_ them at the surfaces of the different planets. That is: it is very probable there is a _matter of light_ or a _luminiferous ether_, diffused through all existing matter, as caloric is, which is _excited by these clouds_, and _thus_ becomes _visible_, which is light, as latent caloric is excited, and becomes sensible, by becoming _free_. Indeed it is very probable _that the matter of heat and light is the same_, and that heat and light are only _different modifications_ of the action of the same substance, excited in a different, or higher degree.] The sun has two _apparent_ motions, namely, the diurnal and annual. By the _former_ he appears to move round the earth in twenty-four hours: and by the latter he appears to traverse that circle in the heavens, called the ecliptic, in the course of a year. These motions, are, however, only apparent: the sun does not travel round the earth in twenty four hours: he does not change his place in the heavens at different seasons of the year. His apparent motions are occasioned by the earth’s real motions. The sun’s apparent diurnal motion is occasioned by the earth’s real rotation about its axis: and the sun’s apparent annual motion is caused by the earth’s real motion in her orbit, through the whole of which she travels in a little less than 365 days, and 6 hours. The fixed stars appear every twenty-four hours to make an entire revolution about the earth. The sun makes the same apparent circuit; but the apparent diurnal motion of the sun is evidently slower than that of the fixed stars. This appearance is occasioned by the daily rotation of the earth on its axis; for while it is turning once on its axis it advances in its orbit a whole degree; therefore it must make more than a complete rotation before it can come into the same position with the sun that it had the preceding day. In the same way, as when both hands of a watch set off together at any hour, as twelve o’clock, the minute hand must travel more than the whole circle before it can overtake the hour hand: hence the difference between solar and sidereal days, which it is important to understand in explaining the equation of time.