DR. ANGUS SMITH ON PEAT. 337 



mosses of the present with the Lepidodendra of the past 

 we find a capacity of growth which must compel us to be 

 careful in our calculations. The rapidity may have been 

 as much greater as the bulk of the tree is greater than 

 now; we see the same rapidity and bulk in warmer 

 climates. If we calculate only ten feet in a century, we 

 obtain two of dry peat, and at least one of very hard peat 

 with our present growth ; with the tropical growth there 

 may be ten times as much. If the growth is in water, the 

 speed seems to be much greater, and gradually ceases as 

 it rises above the level. This would favour the idea so 

 consistently advocated by Mr. Binney, and still not render 

 comparatively dry-grown coal impossible. 



I have tried to make the calculation as to peat — that is, 

 to find by the amount of the resins in the peat and the 

 plant the length of time required for the change ; but it 

 cannot be done until we know better the actual decom- 

 position. This will be an interesting inquiry ; but it must 

 be understood for every class of plants forming peat ; so 

 far as I know, the proximate analysis of many mosses does 

 not exist in chemical books. 



Peat must henceforth be classified with much more 

 minuteness than hitherto ; and the best mode must be 

 found. 



This must not be forgotten — namely, the examination of 

 the plants for resins, fats, and allied bodies ; and this, if I 

 continue the subject, will be considered a prominent point. 

 It will also be important to find in what part of the plant 

 these substances exist ; for although in some the larger 

 portion be confined to the spores, it does not seem to be 

 well to rest entirely on this belief. 



In other words, I should conclude that the plants of 

 coal as of peat would to a great extent, and sometimes 

 wholly, decay, leaving a fine material containing the un- 

 oxidized and insoluble matter, all or nearly all of the fats, 



