RESEARCH METHODS IN STUDY OF FOREST ENVIRONMENT. 25 
Annual Summary. 
The annual summary of air temperatures on the " Summary " form 
should be a tabulation by decades and months of the means or totals 
obtained from the " Air Temperature Record," with the annual mean 
or total, as the case may be, computed therefrom. Usually a separate 
" Summar} T " form will be used for each datum to be summarized. 
In addition, as a part of the annual summary, there should be 
worked out the mean or total for each datum for the growing season. 
The limits of the latter may be determined, as indicated by the dis- 
cussion in earlier paragraphs. 5 Whatever the criterion as to the 
actual length of the growing season, it should be considered to begin 
and end with even decades, and all means computed for the growing 
season should be the sum of the decade means divided by the number 
of decades. 
Form 10. 
Type 
[U. S. Forest Service, Physical Survey.] 
SUMMARY. 
; station No. ; datum 
height or depth 
Year. 
Dec- 
ade. 
Month. 
Mean 
annual. 
Mean 
grow- 
Jan. j Feb. 
Mar. 
Apr. 
May. 
June. 
July. 
Aug. 
Sept. 
Oct. 
Nov. 
Dec. 
ing 
sea- 
son. 
! 
[Determined by comparing annual means for 1 foot and 4 feet.] 
Instruments. 
Approximate 
Thermometers and shelters: range of prices. 
Mercurial thermometer (Weather Bureau pattern) $1.25 to $3.00 
Maximum thermometer (Weather Bureau pattern) 2.50 to 5.00 
Minimum thermometer (Weather Bureau pattern) 1.50 to 3.00 
Maximum and minimum thermometers are often sup- 
plied in pairs. 
Support for maximum and minimum thermometers 2. 00 to 2. 50 
Instrument shelter, complete, without supports 20. 00 to 30. 00 
5 As a matter of fact the temperature conditions that delimit the growth of plants, and 
especially of coniferous trees are not known, and to attempt to fix a rule for determin- 
ing when the growing season begins and ends would, at this stage, be extremely ar- 
bitrary. 
