OBSERVATIONS ON VEGETABLES. 427 



The circumference of trees planted by myself at one foot from 

 the ground (1790). 



Oak in 1730 .... 4ft. 5 in. 



Ash 1730 . . . . . 4 6| 



Great fir 1751 . . . .50 



Greatest beech 1751 40 



Elm 1750 . . . -53 



Lime 1756 . . . 5 5 



The great oak in the Holt, which is deemed by Mr. Marsham 

 to be the biggest in this island, at seven feet from the ground, 

 measures in circumference thirty-four feet. It has in old times 

 lost several of its boughs, and is tending to decay. Mr. Marsham 

 computes, that at fourteen feet length this oak contains 1000 feet 

 of timber. 



It has been the received opinion that trees grow in height only 

 by their annual upper shoot. But my neighbour over the way, 

 whose occupation confines him to one spot, assures me, that trees 

 are expanded and raised in the lower parts also. The reason that 

 he gives is this : the point of one of my firs began for the first 

 time to peep over an opposite roof at the beginning of summer ; 

 but before the growing season was over, the whole shoot of the 

 year, and three or four joints of the body beside, became visible 

 to him as he sits on his form in his shop. According to this 

 supposition, a tree may advance in height considerably, though 

 the summer shoot should be destroyed every year. WHITE. 



FLOWING OF SAP. 



If the bough of a vine is cut late in the spring, just before the 

 shoots push out, it will bleed considerably ; but after the leaf is 

 cut, any part may be taken off without the least inconvenience. 

 So oaks may be barked while the leaf is budding : but as soon 

 as they are expanded, the bark will no longer part from the wood, 

 because the sap that lubricates the bark and makes it part, is 

 evaporated off through the leaves. WHITE. 



