502 ON USEFUL AND BOOK I. 



5. Though a great deal more might be added from known 

 facts which have come under my own observation, or which I 

 have collected from several parts of the country, I shall only 

 offer, in connexion with the above, a few remarks on the effects 

 of priming on trees. The general effects I have already stated 

 to be of a corresponding nature with culture ; that is, to in- 

 crease the quantity of timber produce. The particular manner 

 in which it does this, is by directing the greater part of the sap, 

 which generally spreads itself in side branches, into the princi- 

 pal stem. This must consequently enlarge that stem in a more 

 than ordinary degree, by increasing the annual circles of wood. 

 Now if the tree be in a worse soil and climate than those which 

 are natural to it, this will be of some advantage, as the extra 

 increase of timber will still be of a quality not inferior to what 

 would take place in its natural state ; or in other words it will 

 correspond with that degree of quality and quantity of timber 

 which the nature of the species of tree admits of being pro- 

 duced. If the tree be in its natural state, the annual increase 

 of timber occasioned by pruning must necessarily injure its 

 quality, in a degree corresponding with the increased quantity. 

 If the tree be in a better climate and soil than that which is 

 natural to it, and at the same time the annual increase of wood 

 be promoted by pruning, it is evident that such wood must be 

 of a very different quality from that produced in its natural 

 state. 



