280 Astronomy. [Lecture 18. 



light is the source of all our purest pleasures. 

 His power reaches to a most extended sphere, 

 the more active in proportion to the nearness. 

 Our water would be in a boiling state at Mercury, 

 and frozen at Saturn. Yet the beings who exist 

 in those worlds are undoubtedly accommodated 

 to the climates they inhabit. 



The sun is of a form nearly spherical. He 

 however appears to us only as a circular disc. 

 This is because all the parts of his surface are 

 equally luminous; and consequently there is 

 nothing which can suggest to us that the cen- 

 tr^cal parts are more prominent than the sides, 

 though in reality they are nearer to us by 160,000 

 leagues.^ In the same manner the full moon 

 appears to us a flat surface, but a good telescope 

 corrects the deception. 



So early as the year 1611 spots were discovered 

 upon the disc of the sun. The discovery was 

 claimed both by father Scheiner and by Galileo. 

 These spots consist, in general, of a central part, 

 which appears much darker than the rest, and 

 seems to be surrounded by a mist or smoke; 

 and they are so changeable in their situation 

 and figure as frequently to vary during the time 

 of observation. Some of the largest of them^ 

 which are found to exceed the bulk of the whole 

 earth, are often to be seen for three months to- 

 gether, and when they disappear they are gene- 

 rally converted into faculse or luminous spots, 

 which appear much brighter than the rest of the 



