THE GIRTH-INCREASE OF TREES. 45 
3. HEIGHT OF MEASUREMENTS.—Whenr trees were too young 
to be measured at five feet, a convenient point was chosen two 
or three feet from the ground, and as the trees grew and became 
fit, the point was raised to the five-feet level. I do not think 
the results were in any way invalidated by this necessary 
compromise. 
4. SUMMING-UP OF TABLES.—The entries in the Tables of 
increments due to years in which trees were temporarily ineligible, 
from the effects of transplantation or pruning, are printed in 
etalics, and such entries are not included in the summing 
of the lines and columns. 
5. SCALE USED FOR MEASUREMENTS.—All measurements 
are in inches and decimal parts of an inch unless otherwise 
stated. 
l; “ANNUAL RESULI5, 
Following the plan formerly adopted, I take first the results 
for the species separately, and then the collective results. To 
preserve the convenience of division into decennial and quin- 
quennial periods, I have omitted from the Tables the first year’s 
observations on the second set of trees, but they will be available 
in the text, and will be fully given in the monthly division of 
the subject. 
The chief results derived from the annual observations are— 
1. The annual rate of girth-increase in the species at different 
ages ; 
2. The seasonal range in the species separately ; and 
3. The same in the aggregate. 
The seasonal variations ought to be considered in connection 
with meteorology, but an inquiry of this kind is complicated by 
the variety of influences that come into play, such as the ripening 
of the wood, the formation of the buds, low temperatures of the 
air or earth, the protective or destructive effects of snow, sudden 
thawing, excessively low temperature, excess or defect of rain 
or humidity, &c., besides the effects of position in sheltering or 
exposing different trees to these weather influences. To have 
done justice to all these points would have taken far more time 
than I had atmy command. I have been content therefore to 
