45 z Mr. marsh am^s further Account of the 
fourteen feet contain fix hundred and eighty-fix feet round or 
buyers meafure, or feventeen ton and fix feet ; and fourteen 
feet length of the Hampfhire Oak is one thoufand and feven 
feet, or twenty-five ton and feven feet, that is, three hun- 
dred and twenty-one feet more than the Yorkfhire Oak, though 
that is fuppofed by many people the greateft Oak in England. 
I am unwilling to conclude this account of wafhing the 
ftems of trees without obferving, that all the ingredients of 
vegetation united, which are received from the roots, ftem, 
branches, and leaves of a mofiy and dirty tree, do not produce 
half the increafe that another gains whofe ftem is clean to the 
head only, and that not ten feet in height. Is it not clear that 
this greater fhare of nourifhment cannot come from rain ? for 
the dirty ftem will retain the moifture longer than when clean, 
and the nourifliment drawn from the roots, and imbibed by 
the branches and leaves, muft be the fame to both trees. Then 
muft not the great fhare of vegetative ingredients be conveyed 
in dew ? May not the mofs and dirt abforb the firieft parts of 
the dew ? and may they not aft as a kind of fcreen, and de- 
prive the tree of that fhare of air and fun which it requires ? 
To develope this myfterious operation of nature would be an 
honor to the moft ingenious, and the plain faft may afford 
pleafure to the owners of young trees ; for if their growth 
may be increafed by cleaning their ftems once in five or fix 
years (and perhaps they will not require it fo often) if the in- 
creafe is but half an inch yearly above the ordinary growth, 
it will greatly over-pay for the tiouble, befides the pleafure of 
feeing the tree more flourifhing. Although the extra increafe 
of my firft wafhed Beech was but four- tenths of an inch, the 
fecond was nine-tenths and a half, and the third near two 
inches, fo the aggregate extra increafe is above one inch and 
one- 
