UNCLE IN ENGLAND. 



asked him why the lumps of wet clay were 

 broken by frost, which I thought would only have 

 hardened them the more, like the road on which 

 we were walking. 



(t The reason why the clods of wet earth are 

 burst by the frost, is, that the water which they 

 contain becomes ice; and, in doing so, it swells, 

 and therefore requires greater space than while it 

 was water. In the process of freezing, water crys- 

 tallizes, and every crystal drives away the adja- 

 cent particles which interfere with its exact forma- 

 tion. This does not happen to hard roads, such 

 as we are now walking upon, because they are 

 closely bound, and do not admit the previous en- 

 trance of the moisture ; but if the road was soft 

 and spongy, you would then probably see, in its 

 rough and uneven face, the effect of the frozen 

 water. When we return home, if you look at the 

 piece of gravel walk which was lately made, and 

 is not, therefore, yet bound, yon will observe 

 what a curious appearance the frost gives it ; the 

 larger stones, which by their weight prevented 

 the water from spreading under them, will ap- 

 pear sunk ; while the sandy, spongy part which 

 imbibed the rain, is swelled by the frost, and 

 raises the surface of the walk. All crystals have 

 a regular form, and in assuming it, they are 

 obliged to recede a little from each other'; each 

 crystal, it is true, has but little power, but as 

 their number is almost infinite, their combined 



