OAK. 



on the surface for a yard or two around the plant, 

 and by nearly covering a like distance by pieces of 

 black trap rock, from three to six inches in diameter. 

 The success from the pieces of trap appeared greatest; 

 they diminished the evaporation from the ground, 

 thence less loss of heat and of necessary moisture ; 

 and being at once very receptive of radiant caloric, 

 and a good conductor, they quickly raised the tem- 

 perature of the soil in the first half of the summer, 

 when bodies, from the increasing power of the sun, 

 are receiving much more heat by radiation than they 

 are giving out by radiation. 



The oak should never be pruned severely, and 

 this rule should be particularly observed when the 

 tree is young. We have known several of the most 

 intelligent gardener-foresters in Scotland err greatly 

 in this ; and, by exclusively pruning the oak plants, 

 from misdirected care, throw them far behind the 

 other kmds of timber with which they were mixed 

 in planting. There is no other broad-leaved tree 

 which we have seen suffer so much injury in its 

 growth, by severe pruning, as the oak. The cause 

 of this may be something of nervous susceptibility, 

 or connected life, all the parts participating when 

 one is injured ; it may be owing to the tendency to 

 putrescency of the sap-wood, or rather of the sap, the 

 part around the section often decaying, especially 



