k.. M. 



I P.M. 



7 P.M. 



Mean. 



89 



64 



76 



76 



85 



61 



72 



73 



90 



80 



85 



85 



92 



77 



86 



85 



AGRICULTURAL EXPERIMENT STATION. 269 



Percentages of Moisture, 

 summary for seven months. april to november, 1889. 



Hygrometer >)o. 1. in open tield, 



•• 2. 



" '" 3. in forest, 



'• " 4, • •• 



Regarding the mean results from hygrometers Nos. 1 and 2 as 

 indicating percentages for the open field, we have the following 

 summary of results : 



7 A. M. I p. M. 7 P. M. Mean. 



Percentages of moisture, open field, 87 62 74 74 



Regarding the mean results from hygrometers No. 3 and 4 as 

 indicating percentages for forests only moderately dense, we have 

 the following summary results : 



7 A. M. I p. M. 7 p. M. Mean. 

 Percentages of moisture, forest, 91 78 86 85 



Comparing results, open field and forest, we have excess of 

 moisture in forest above that in open field expressed in per- 

 centages. 



7 A. M. : p. M. 7 P. M. Mean. 



4 16 12 11 



It thus appears that from observations covering the period of 

 growth of one season, that the excess of moisture in forest above 

 that of open field in the morning, amounts to but 4 per cent., 

 while in the middle of the day it rises to 16 per cent., and at 

 night- fall drops down to 12 per cent., and that the mean excess 

 for the day is 11 per cent. In a very dense forest the percentage 

 of excess would undoubtedly rise much higher. The presence of 

 patches of forest in any region cannot but exert a marked influence 

 on the hygroscopic conditions of the atmosphere, and this condi- 

 tion, in turn, is an important factor in the growth of vegetation. 



It was noticable in the investigation given that proximity to 

 running water during two-thirds of the period of experiment only 

 compensated for the loss of moisture resulting from the more open 

 character of the forest where hygrometer No. 4 was situated as 

 compared with No. 3. 



It is designed that this examination of the effect of forests on 

 the moisture of the atmosphere shall be continued. 

 Soil Temperatures. 



In this investigation a knowledge of the temperature of the soil 

 at different depths, during the growing season, is sought. 



