37 



by the modern astronomers ; so is the magnitude of the 

 heavenly bodies proportionally less th^n they suppose. 

 For instance ; the diameter of the sun, commonly sup- 

 posed to be 822, 148 miles, is according to this manner of 

 calculating, 23,373 and no more. And that this is nearly 

 the true diameter, and these the true distances appears 

 from experiments on the transits of the planets over the 

 sun." 



The' comets, Dr. Rogers thinks, are chiefly designed 

 to repair the quantities of light continually emitted by 

 the sun, and which are scattered and dispersed over the 

 whole system. Their sweeping tails, which extend so 

 many thousand miles, seem adapted to such a purpose. 

 And as many of those particles of light, are driven to a 

 vast distance, it is necessary they should go to the ut- 

 most limits of the system, to make such a collection. 



Suppose a body fit for this, detached from the neigh- 

 bourhood of the sun, it should be light, porous and 

 spongy. And such a body would be propelled by the 

 violence of the rays, with great velocity to a great dis- 

 tance. The farther it goes, the fewer rays strike upon 

 it, and their force likewise is diminished. The comet 

 then slowly sweeps his tail over the wide expanse, beyond 

 the orbit of Saturn. There its cells are filled with the 

 matter it was sent 'to collect ; but becoming heavier, the 

 other scale begins to preponderate, and he slowly re- 

 turns toward his centre. His collection increases as he 

 descends, which adds to his weight and swiftness, and he 

 comes down, if very heavy, almost in a strait line ; if less 

 so, in a larger curve, till he is near the sun, where hav- 

 ing emptied himself, and being evenly balanced with the 

 repelling rays, he moves round in the segment of a circle, 

 till being continually lighter, he is no longer a balance 

 for the repelling rays, and so is driven forward thereby, 

 and runs the same circle as before. 



What a violent blow is here given to the whole fabric 

 cG 



