1912. 



PUBLIC DOCUMENT — No. 31. 



147 



Bj comparing the results given in these tables it will be seen 

 that the resistances obtained from the north, south, east and west 

 sides of the tree showed some variation from day to day, and 

 also on different sides of the tree. In the maple a slightly 

 higher average resistance was shown on the north side of the 

 tree than on any other side, followed by the east, west and south 

 sides. 



In the case of the elm (Table II.), however, the highest aver- 

 age resistance was shown on the south side for the same period, 

 this being followed by the west side, while the cast side showed 

 the least resistance. The resistance in both cases showed a tend- 

 ency to decrease towards the latter part of April, when the tem- 

 perature increased, as is shown by a comparison of the mean 

 daily minimum and maximum temperature records which were 

 taken from the station's meteorological observatory located 

 nearby, and which are given in both tables. The highest average 

 resistance for the maple was given on the 9th of April, when 

 there was the lowest mean temperature. The highest average 

 resistance given by the elm occurred on April 6 and April 8 (the 

 records were not taken on the 9th), while the lowest average 

 resistance for the maple occurred April 23, during one of the 

 highest mean temperature days. The lowest average resistance 

 for the elm occurred April 26, which date gave the highest mean 

 temperature. 



Table III. — Shoiving Electrical Resistance (in Ohms) of Maple {Acer 

 saccharum, Marsh), covering a Period of Nearly Three Months. Re- 

 sistances taken on the North, South, East and West Sides of the Tree 

 about Midday. 



[Electrodes 10 feet apart. Mean daily temperatures given in degrees F.] 



Date. 



Tempera- 

 ture. 



East. 



South. 



West. 



North. 



April 7, . . . 



14, . . . 



21, . . . 



26, . . . 



Average for month, 



19,000 

 20,000 

 19,500 

 15,700 



18,840 

 19.400 

 19,500 

 15,000 



18,550 



18,185 



22,000 

 22,000 

 22,000 

 16,000 



20,500 



22,000 

 22,000 

 21,000 

 18,200 



20,800 



