1 78 PHYSICAL SCIENCE BK. iv 



and for one that I am going to make. He will assure 

 you, as confidently as if he had witnessed the pro- 

 cess of formation, that hail is formed from a cloud 

 that is charged with rain, and has already turned 

 into moisture. You can discover without a tutor 

 why the hail is round if you observe that drops of 



3 all kinds tend to become globular. This is seen, 

 for example, in looking-glasses, which gather mois- 

 ture from the breath, as well as in cups, and any 

 other smooth surface bedewed with it. So, too, 

 in the leaves of grass or trees, any drops that 

 adhere take a circular form. 



What is harder than rock, what softer than water ? 



Yet the hard rock is hollowed by drops of the soft water ; 



or, as another poet tells us : 



The drip by its fall hollows the stone : 



4 and this hollow is itself round. Whence it is 

 evident that its shape resembles this drip which 

 hollows it out, sculpturing the spot to its own 

 form and character. Besides, the hail, even were 

 it not of this shape, might be rounded in its 

 fall, and worn equally on all sides into globular 

 form as it is again and again whirled round in 

 its descent through the space of thick air it 

 traverses. Snow, on the contrary, cannot be affected 

 thus, because it is not so solid, being indeed 

 very much scattered, and falling from no great 

 height. It has its source in the neighbourhood of 

 the earth, and its descent is of no great distance 

 through the air, but starts from a point quite close 



5 by. Why should I not allow myself the same licence 

 as Anaxagoras in differing from my authorities ? 

 Nowhere can equality of rights be claimed with 

 more propriety than among the philosophers. Hail 



