246 



ever; and the motion of the planets round him is per- 

 formed in the same time ; of consequence, his quantity of 

 matter still continues the same. How then is this vast 

 waste supplied ? May there not be millions of bodies 

 attracted by him from the boundless regions of space, 

 that are never perceived by us 1 Comets on their road 

 to him, have several times been accidentally discovered 

 by telescopes that were never seen by the naked eye. 

 Indeed the number of black spots on the sun,/ seems to 

 indicate, that there is always a quantity of matter there 

 only in preparation to give light, but not yet refined and 

 pure enough to throw off rays like the rest of his body. 

 For I think we can hardly conceive, that any matter 

 can remain long on the body of the sun without be- 

 coming luminous ; and so we find these spots often disap- 

 pear ; that is to say, the matter of which they are com- 

 posed is then perfectly melted, and has acquired the 

 same degree of heat and light as the rest of his body. 

 Even in glass houses, and other very hot furnaces, most 

 sorts of matter very soon acquire the same colour and 

 appearance as the fire, and emit rays of light like it. 

 But how much more must this be the case at the surface 

 of the sun ? When Newton computes, that even at 

 many thousand miles distant from it> a bedy would ac- 

 quire a degree of heat two thousand times greater than 

 that of red-hot iron. It has generally been understood, 

 that he said the great comet really did acquire this degree 

 of heat : but this is certainly a mistake : Sir Isaac's ex- 

 pression, to the best of my remembrance, is, that it might 

 .have acquired it. And if we consider the very great 

 size of that body, and the short time of its perihelion, the 

 thing will appear impossible ; nor indeed do I think we 

 can conceive" that a body only as large as our earth, 

 (and the spots on tlie sun are often much larger), could 

 be reduced to fusion even on his surface, but after a con- 

 siderable space of time. 



Now it seems to be universally supposed, that the 

 rays of light are really particles of matter, proceeding 

 from the bodv of the sun. If so it is absolutely necessary 

 that we should fall upon some such method of sending 



