246 NATURAL THEOLOGY. 



forth rays sufficient to fill a hemisphere of a mile diameter, 

 and to fill it so full of these rays, that an aperture not larger 

 than the pupil of an eye, wherever it be placed within the 

 hemisphere, shall be sure to receive some of them. AVhat 

 floods of light are continually poured from the sun, we can 

 not estimate ; but the immensity of the sphere which is filled 

 "vvith particles, even if it reached no further than the orbit of 

 the earth, we can in some sort compute ; and we have rea- 

 son to believe, that throughout this wliole region, the parti- 

 cles of light lie, in latitude at least, near to one another. The 

 spissitude of the sun's rays at the earth is such, that the 

 number which falls upon a burning-glass of an inch diame- 

 ter is sufficient, when concentrated, to set wood on fire. 



The tenuity and the velocity of particles of light, as 

 ascertained by separate observations, may be said to be pro- 

 portioned to each other ; both surpassing our utmost stretch 

 of comprehension, but proportioned. And it is this propor- 

 tion alone which converts a tremendous element mto a wel- 

 come visitor. 



It has been observed to me by a learned friend, as hav- 

 ing often struck his mind, that if light had been made by a 

 common artist, it would have been of one uniform color ; 

 whereas, by its present composition, we have that variety of 

 colors which is of such infinite use to us for the distinguish- 

 ing of objects — which adds so much to the beauty of the 

 earth, and augments the stock of our hinocent pleasures. 



With which may be joined another reflection, namely, 

 that considering light as compounded of rays of seven difier- 

 ent colors — of which there can be no doubt, because it can 

 be resolved into these rays by simply passing it through a 

 prism — ^the constituent parts must be well mixed and blended 

 together to produce a fluid so clear and colorless as a beara 

 of light is, when received from the sun. 



