FARADAY 



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 toward bodies which 

 fall to it, but, that all these bodies possess an attraction 

 every one toward 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 

 proportion 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 together, I should not be able, by the 

 most delicate arrangement of apparatus, to make you, or 

 myself, sensible that these balls did attract one another; and 

 yet we know that such is the case, because if, instead of 

 taking a small ivory ball, we take a mountain, and put a ball 

 like this near it, we find that, owing to the vast size of the 

 mountain as compared with the billiard ball, the latter is 

 drawn slightly toward it, showing clearly that an attraction 

 does exist, just as it did between the shell-lac which I rubbed 

 and the piece of paper which was overturned by it. 



Now it is not very easy to make these things quite clear at 

 the outset and I must take care not to leave anything unex- 

 plained as I proceed, and, therefore, I must make you clearly 

 understand that all bodies are attracted to the earth, or, 

 to use a more learned term, gravitate. You will not 

 mind my using this word, for when I say that this penny- 

 piece gravitates, I mean nothing more nor less than that 

 it falls toward the earth, and, if not intercepted, it would 

 go on falling, falling, until it arrived at what we call the 

 centre of gravity of the earth, which I will explain to you 

 by-and-by. 



I want you to understand that this property of gravitation 

 is never lost; that every substance possesses it; that there is 

 never any change in the quantity of it; and, first of all, I 

 will take as illustration a piece of marble. Now this marble 

 has weight, as you will see if I put it in these scales; it 

 weighs the balance down, and if I take it off, the balance goes 

 back again and resumes its equilibrium. I can decompose 



