THE GIRTH-INCREASE OF TREES. 89 
as the beginnings and endings are very gradual it would be per- 
haps impossible to define their precise limits by girth measure- 
ments. On the whole, however, a division into a first half-season 
consisting of April, May, and June, and a second comprising 
July, August, and September, besides being very convenient, is 
probably fair enough. 
It appears from the little Table annexed that in three of the 
years 1892 to 1895 the half-seasonal results were remarkably 
uniform, being nearly as 45 to 55 in favour of the second half, 
but that in 1893 the proportion was slightly in favour of the 
first half, thus reducing the four years’ averages to 47, 53, in 
round numbers. 
1st Half 2nd Half 
Season. Season, 
1892, ... os ie fa 45°3 | 54°7 
1893, ... aie a — 52°23. 47°8 
1894; me i oe 44°5 555 
ASS =. = = is 44-7 55°3 
ANOUNO 8 i ae ae Pe OT 53°3 
The young trees observed in 1887-91 yielded a somewhat 
greater superiority for the second half-season, the figures being 
44,56. This is no great difference, but when a comparison is 
made with the adult and aged trees of 1882-87 the superiority 
of the second half in them is much more marked, the figures 
being 35, 65, proportions which are very little affected, as I find, 
by limiting the comparison to the species which are represented 
in both sets of trees. Thus, the result arrived at in 1891—that 
adult and old trees have a greater tendency than young ones to 
throw their main girth-increase into the second half-season—is 
amply confirmed by the more recent observations. 
The variation or range of the half-seasons would have been 
almost 727 but for the exceptional year 1893; even with it the 
figures are only 44 to 52 for the first half and 48 to 55 for the 
second, in round numbers. 
D 
