VOL. XXVII.] PHILOSOPHICAL TRANSACTIONS. Q27 



" Thirdly, for the manner of their appearance. I have seen many spots, 

 which in the middle of the sun appear of a round body, but coming towards 

 the side of the sun, appear long. Which (if you rightly consider it) is a de- 

 monstrative argument that they are not globes, as all the planets and stars are : 

 for globes always appear of one form (round) in every position ; but exhalations, 

 or such like fluid substances, extended to a broad flat form, like our clouds, 

 which being over our heads, and so in their full breadth, appear large and broad; 

 but driven with the wind, till they turn one edge upon us, seem of a long 

 shape. So these solar clouds, being turned about the sun, may in the middle 

 shew their full breadth to us, and about both edges of the sun, turn their edges 

 to us : which answereth to the appearance. 



*' Fourthly, for their continuance. Some of these spots, arising at the east 

 side of the sun, vanish before they come to the midst of the sun. Others ap- 

 pear first in the middle of the sun, and vanish before they come to the westera 

 limb ; and for the most part they vanish before they have made a full revolution 

 about the sun. Which argues them to be but thin, vanishing, fading substances, 

 not like the permanent bodies of the stars. 



" But to take off these reasons, you answer, that you conceive these spots 

 to be stars moving regularly in their own orbes, which are many, though none 

 of greater extent than about -pV of the 0's semidiameterfrom its circumference; 

 and that the swifter movers in the lower orbes, overtaking the slower in the 

 higher orbes, cause an appearance. You seem therefore to think, that they 

 being so thin bodies, the sun's rayes pass through them, and so one cannot be 

 seen alone, till more being together, one heaped beliind another, they stop the 

 light of the sun's rayes, and so cause an appearance. This I conceive is your 

 meaning : or else (as you seem to insinuate afterwards) that the higher reflects 

 the sun's rayes strongly enough upon the lower (when they come within the 

 angle of reflection) to make the interjacent planet indiscernable. 



" But to these I answer, 



1. " If it be by their coming within the angle of reflection, that the light of 

 the sun reflected from the outer planet upon the inner, doth make it (as you 

 speak) indiscernable, then that light so reflected is reflected either upon all 

 places, as the moons and planets light ; or but upon one, as is the reflection of 

 a plain looking-glass. If the first, there would never be many seen (seldom 

 above one or two) because the outermost would continually make the inner un- 

 discernable. But Gassendus affirms, there are seen sometimes 40 at once in 

 the sun's body. If the 2d, there would always be many seen, because the re- 

 flected light would but occupy a little room, and that but for a small time, till 

 the swifter were past the place of reflection : whereas many days there are 



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