PAPERS ON BOTANY 251 



ments were therefore practically hidden from view. This 

 was necessary to prevent their being tampered with by 

 hunters or other pedestrians. The bottomland station 

 chosen was abont 50 feet from tlie bottom of the slope 

 in the middle of a dense patch of wood nettle and touch- 

 me-not. 



The thermometers used were of the type sold by Henry 

 J. Green of Brooklyn, X. Y. Each thermometer is en- 

 closed in a wooden ease and has an exposed scale about 

 eleven inches long. Two thermometers were used at each 

 station: one for taking the temperature at a depth of 

 three inches and the other at a depth of tAvelve inches. 

 These are the depths at which series of readmgs have 

 been taken for the Committee on Soil Temperature of 

 the Ecological Society of America by a number of colla- 

 borators in different parts of the United States. The 

 thermometers were set on June 21, 1918, and left imdis- 

 turbed until September 25, 1918. Keadings were made on 

 both of these dates and on seven intervening dates. The 

 readings were in every case made as near to 12 o'clock 

 noon as possible and always in the same order, tlie ther- 

 mometers at the upland station being read first and those 

 at the bottomland station about five minutes later. 

 Tables I and II give the results of these readings in de- 

 grees Fahrenheit. 



TABLE I 



Soil temperatures at depth of three inches 



Date Upland Bottomland Difference 



June 21 67.0 64.0 3.0 



June 24 62.5 59.0 3.5 



July 5 69.0 66.2 2.8 



July 6 6S.0 65.5 2.5 



July 12 62.7 61.2 1.5 



July 13 63.0 61.2 1.8 



Aug. 12 75.5 72.2 3.3 



Aug. 27 72.0 70.0 2.0 



Sept. 25 55.0 53.2 l.S 



Average 66.0 63.6 2.4 



