ATTKA.CTION OF THE EAETH. 9 



water and pour it in, you see that that side of 

 the scales immediately goes down ; that shows 

 you (using common language, which I will not 

 suppose for the present you have hitherto ap- 

 plied very strictly) that it is heavy, and if I put 

 this additional weight into the opposite scale, I 

 should not wonder if this vessel would hold 

 water enough to w^eigh it down. [The Lecturer 

 poured more water into the jar, which again 

 went down.] Why do I hold the bottle above 

 the vessel to pour the water into it ? You will 

 say, because experience has taught me that it is 

 necessary. I do it for a better reason because 

 it is a law of nature that the water should fall 

 towards the earth, and therefore the very means 

 which I use to cause the water to enter the 

 vessel are those which will carry the whole body 

 of water down. That power is what we call 

 gravity, and you see there [pointing to the 

 scales] a good deal of water gravitating towards 

 the earth. Now here [exhibiting a small piece of 

 platinum ( 2 )] is another thing which gravitates 

 towards the earth as much as the whole of that 

 water. See what a little there is of it that 

 little thing is heavier than so much water 

 [placing the metal in opposite scales to the 



