OF TREE BRANCHES AT FREEZING TEMPERATURES 47 
The following experiment was tried. A branch curved in 
form, was cut from the linden and at once artificially cooled to 
o° F., in a salt-ice pack, but showed no change of curvature 
between 0° F. and 40° F. The experiment, however, was 
not conclusive, since the branch was not longer than about three 
| 
| 
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4 t 
8 Linden 
7 Depression per 1b,,470 F., .029 ft. 
. 1 = = 420° FL. .0a3. * ns G7 ORE 
6 cB * Lied 
: Paulownia a 
7.5 a Depression per ye ~ . 1ones ft. Pee See Sem 
i . ea 
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A 
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NSN 
9 Y 
70 | *— 
4 NH 
8 a Tree No. 2 Paulownia 
7 NL Sf | | le Branch A is 
ahh Seae 
65+ 5 N \ . Feb, 6,20°F. _| | | 
Sar MN a i. Dee FE ATP ee 
eae. AA ort 4 
ae SCL ACL 
ile A 7 Tree No.1 Linden 
60 | TN Branch B |_| 
a‘ Po alec 
4 TY Dec. 31, 47°F. —[—]— 
8 KOA rates Wed Gea 
, SUPPLE 
i Writ Pat 
sy ee 
5.5 Feb.6, 20°F, Linden 
y | i | i i 
: rouse ttt [| 
o § 10 I5 20 25 30 35 40 45 50 SS GO 
Fic.16. Effect of loading Branch B, Tree No. 1 (European linden), and Branch 
A, Tree No. 2 (Paulownia tomentosa), at two differenttemperatures. The modulus 
of elasticity constant is less in both cases at temperatures below freezing, which is to 
be expected. Achange of the constant, therefore, does not account for any part 
of the depression of the branches A, B and C, Tree No. 1 (linden), with low tem- 
perature since the effect of the change of the modulus is opposite to the thermom- 
etric movement observed. 
feet. It was ascertained definitely, however, that certain 
branches which were curved upward on the linden became more 
curved when subjected to low temperature. This fact was found 
by attaching str'ngs to the ends of branches which were curved 
