14 GRAVITATION. 



it would swing to and fro in the same manner, 

 and in the same time too. Do not be startled 

 at this statement ; I repeat, in the same manner 

 and in the same time, and you will see by and 

 by how this is. Now, that power which caused 

 the water to descend in the balance which 

 made the iron weight press upon and flatten the 

 bubble of air which caused the swinging to 

 and fro of the pendulum, that power is entirely 

 due to the attraction which there is between 

 the falling body and the earth. Let us be slow 

 and careful to comprehend this. It is not that 

 the earth has any particular attraction towards 

 bodies which fall to it, but, that all these 

 bodies possess an attraction, every one towards 

 the other. It is not that -the earth has any 

 special power which these balls themselves have 

 not, for just as much power as the earth has to 

 attract these two balls [dropping two ivory 

 balls], just so much power have they in propor- 

 tion to their bulks to draw themselves one to 

 the other ; and the only reason why they fall so 

 quickly to the earth is owing to its greater size. 

 Now, if I were to place these two balls near to- 

 gether, I should not be able, by the most deli- 

 cate arrangement of apparatus, to make you, or 



