40 TROWBRIDGE: THE THERMOMETRIC MOVEMENTS t 
absorbed a good deal of time, and the desirability of an extension 
of the records to branches of different forms was not foreseen. 
Temperature and relative humidity observations taken from 
the United States Weather Bureau have been used in a few cases. 
The Draper Observatory in Central Park, where these observations - 
were made, is not more than three miles distant from the Columbia 
University grounds, and since it was shown by the thermometer — ; 
records at the two places that the temperatures were usually 
within a degree or so of each other they agree sufficiently in the 4 
present case. No relative humidity observations were made, but 
the Draper Observatory record of the moisture was sufficiently - 
Guek Reed 1 Pa ao ie ee : : 
| HEIGHT OF BRANCH pea 
— Branch A_ Tree No.1 
va Branch B__s Tree No. 1 
A Laoal be ——+ 
ra A Linden i 
OEE Beer 
aes ES 
ao ee 
' Relative Humidity U.S. Westher Burenu_| |_| b= ; 
iS ae I A aoe: 
oo oon ee as | | - | | | [ Br - ; 
iss Freezing point any ee Se SS GA Temperature F U.S. Weather Bureau Mae’. ce 4 
ol gt watt 7 re ture F = | 
30} S ve. ah emper i 
ae: i 
Re é | 
2016 |} 
o| & jae 
18+ pad 13 
ale } 
is - 
s° E 
o i 
AMIO ih 12 23 % 5 6 7 8 QEM. FEB. 23%1912 
F Hourly record of Branches A and B, Tree No. 1 (European linden), — 
showing rise of temperature through the freezing point and subsequent fall. 
the branches appear to respond quickly to the changes in temperature and there | 
also appears to be a slight thermometric movement above freezing. 
i) 
a 
close for the use to which it was put, since large changes in relative - 
humidity appeared to have little or no effect on the position of 
the branches. 
DAILY RECORDS AND EXPLANATION OF CURVES SHOWN IN FIGS: 
4, 5, 6, 7 AND 8 
The daily record of Branch A, Tree No. 1 (linden), is given in 
Fics. 4 and 5, for February, March, April and May. The fac 
shown by these curves are as follows: 
