THE SUN. 59 



ought to be capable of sustaining 3 lb. 10 oz. 386 grs. 

 If it be weaker it will break. And this is the force or 

 effort which the hand must steadily exert, to draw the 

 stone in towards itself, out of the direction in which it 

 would naturally proceed if let go ; and to keep it revolv- 

 ing in a circle at that distance. 



(15.) Now, what the string does to the stone in the 

 sling, that, in the case of the sun retaining the earth in 

 its orbit, is done that same office is performed that 

 effort (in some mysterious way which the human mind is 

 utterly incapable of comprehending) is exerted that 

 pull communicated \ in an instant of time, and so far as 

 we can discover, without any material tie; by the force 

 of gravitation. We know the time the earth takes to 

 revolve about the sun. It is a year; of so many days, 

 hours, minutes and seconds ; and we know its distance 

 95,000,000 of miles, which may easily be turned into 

 yards. Well, now, suppose a stone or a lump of lead of 

 a ton weight to be tied to the sun by a string, and slung 

 round it in such a circle and in such a time. Then, 

 on the very same principles, and by the same rules of 

 arithmetic, one may calculate the amount of pull, or 

 tension of the string, and it. will be found to come out 

 1 lb. 6 oz. 51 grs. 



(16.) We all know what sort of lifting power what 

 amount of muscular force it takes to sustain a pound 

 weight. Multiply this by 2240 and you have the mus- 

 cular effort necessary to sustain a ton. It would require 

 three or four strong horses straining with all their might. 

 Well, now, it is one of the peculiarities of this mysterious 



