46 CHRISTISON—OBSERVATIONS ON 
deal only with instances in which the cause of a marked 
depression was not far to seek. None such occurred in the 
second decade, but the first was signalised at the outset by an 
unprecedented series of three most unfavourable seasons, chiefly 
owing to exceedingly low winter temperatures, which reduced 
the aggregate increment by nearly one-half, and affected some 
trees for years afterwards, if not permanently. ‘The disastrous 
effects on girth-increase of these seasons have been described in 
former papers by my father* and myself,t and will be only 
incidentally mentioned now. 
A. General History of the Species Separately. 
In place of taking the species in scientific sequence, it was 
deemed preferable to deal with them in the order of the 
reliability of the observations, whether depending on the larger 
number of observations, or on the better thriving of the species 
in the soil of the Garden. A certain preference has also been 
given to the importance of the species as forest trees. 
Each Table is drawn up so as to show— 
(1) The following results in the original adult or old trees of 
1878 :—a. The average increase in girth for the first decade for 
each tree under observation. 6 The annual increase in detail 
for the second decade. ¢. Its total amounts and its average 
annual rate. ad. The girth of each tree at the end of the 
decade in 1897. 
(2) The same details, as far as they go, in the second decade 
for the younger trees selected in 1887 and 1892, given at the 
foot of the Tables. 
* On the Exact Measurement of Trees, Part 4. Trans. Bot. Soc. Ed., 1880. 
+ Of. cit., 1880-89, p. 397. The Depression in Girth-Increase of 1879, 1880, and 
1881 ; e¢ passim. 
[ TABLE. 
