Additional Observations, since 1897, on the Girth- 
increase of Deciduous Trees in the Royal 
Botanic Garden, Edinburgh, and their 
connection with the Twenty Years’ Observa- 
tions (1878-97) previously published. 
BY 
DAVID: CHRISTISON, M.D., LL.D: 
INTRODUCTION. 
The results of the observations begun by my father in 1878, 
and continued by me after his death in 1882, have been 
published from time to time down to the year 1897.* They 
principally deal with, and determine with sufficient accuracy, the 
average annual and monthly rates of girth-increase in a large 
number of deciduous trees. In accordance with the tapes then 
in use, the records were kept in twentieths of an inch. But the 
introduction of the fine steel tape of Chesterman, graduated to 
millimetres, insured an accuracy previously unattainable, and all 
my measurements since 1897 have been taken with this tape, 
the records being kept in millimetres, and even in half-milli- 
metres. As my confidence increased, I initiated new inquiries 
and reduced the intervals of the observations to five days in 
general, besides recording occasionally, for short terms, at inter- 
vals of two days or daily, and finally three times a day. 
For purposes of comparison, and to link on the new with the 
old records, it was necessary to reduce the parts of an inch in 
*1. On the can Gsm gy nag! Trees. By Sir R. Christison, Baronet. 
Trans. and Proc. Bot. Soc., Edin., 1879-80-81 
2. Obse anor ee “he i Pear: poe Monthly Growth of hanes e" R. 
oe ae. r. D. Christison. Trans. R.S.E., XXXII., 
3. Weekly Rate of Girth- increase in Ti res, and its Relation i. the 
. of 8 Leaves and Twigs. Trans. and Proc. Bot. Soc., Ed., 1891. 
r. ristiso 
4. The Gi vad acre of Trees in the Royal Botanic Garden, Edinburgh, 
for Twenty Years (1878-97). Notes, R.B.G., Edin., No. III, 1900 ; No. IV., 
IgoI. 
[Notes, R.B.G., Edin., No. XVII., April 1907.] 
