2 5 o IN STARRY REALMS. 



The most intense light we know of comes, of course, 

 from the light which rules by day, from our sun himself. 

 The sun pours his unrivalled beams around us in all di- 

 rections with prodigal abundance, notwithstanding his 

 enormous distance of ninety-three millions of miles. Let 

 me describe an experiment with respect to our sun, an 

 experiment, it is needless to say, which could never be 

 performed, but the results to which it leads us are none 

 the less certain. Astronomers have demonstrated them in 

 many other ways. 



Suppose that the sun were gradually to be moved away 

 farther and farther into space ; suppose that by this time 

 to-morrow the great luminary should be twice as far as 

 it is now, and the next day should be three times as far, 

 and the day after that four times, and so on until in a 

 year's time we should find that the sun was 365 times the 

 distance from us that it is at present. Let us now trace 

 the changes which we should see in the brilliancy of our 

 orb of day. When he had reached double his distance 

 from us we should find that the light had decreased to a 

 quarter of its present amount, and the heat which we 

 derived from his beams would have decreased in the same 

 proportion. In ten days we should find that the light 

 had become so feeble as to be only one-hundredth part of 

 that which we enjoy now. The apparent size of the sun 

 would also be steadily decreasing, for as the distance of a 

 body increases its apparent dimensions diminish. Some- 

 times the diminution of apparent size with distance is well 

 illustrated on a clock tower. You would hardly believe 

 that the hands and face of a clock like that at West- 

 minster were so large until you happen to see a man 



