148 MAINE STATE COLLEGE 



Orono, has been oliserver durino; the four years that this work 

 has beeu carried ou. In this report the results of observations 

 made during the years 1889, 1890, 1891 and 1892, are combined. 



The several problems considered appear in definite order, in the 

 following pages. The first to which attention has been given, is 

 a determination of the percentage of moisture in forest as com- 

 pared with that in open field. 



The arrangement of instruments for this investigation is here- 

 with submitted. 



Hygrometer No. 1 is placed in a wooden stand constructed for 

 thermometrical instruments and located in the open field remote 

 from buildings. Hygrometer No. 2 also is enclosed in a wooden 

 box, perforated to allow a free circulation of air, and located also 

 in the open field. Hygrometer No. 3 is also enclosed in a perfo- 

 rated box attached to a tree in a moderately dense forest. Hygro- 

 meter No. 4 is placed in a similar box attached to a tree in a portion 

 of the forest a little more open than that in which No. 3 is located, 

 but near which is a running brook except during the driest part of 

 the summer. 



Each hygrometer is about four feet above the surface of the 

 ground. Readings are taken three times daily, at 7 A. M., at 1 

 P. M., and at 7 P. M., local time. 



Observations were commenced April 5, 1889 and they have 

 been continued through the growing seasons of 1889, 1890, 1891 

 and 1892. 



The monthly averages are given in the following tables on the 

 scale of 100. 



