Squires: tree temperatures. 453 



bulb mercurial thermometer hung within a few meters of the 

 trunk. This instrument was sheltered from the direct rays of 

 the sun except for two or three hours in the middle of the after- 

 noon. In order to obtain the temperature of the tree a cavity 

 1cm. in diameter and 8cm. in depth was bored into the trunk at 

 breast height, on the north side. The inner end of the cavity 

 was slightly higher to prevent accumulation of liquid either 

 from precipitation or sap. In this cavity was inserted the bulb 

 of a mercurial thermometer designed for the purpose. The 

 bulb of this thermometer was cylindrical in shape, 2.3cm. long 

 and .7cm. in diameter. The tube was 32cm. in length and was 

 bent at right angles at a distance of 9cm. from the bulb. The 

 long arm of the tube was graduated from -lO^C. to lOO^C. The 

 entire length of the mercurial tube was enclosed in a sheathing 

 tube fused to the upper end of the bulb and sealed at its upper 

 end. The portion of the sheathing tube around the short arm of 

 the mercury tube was 1cm. and that around the long arm was 

 2cm. in diameter. By this arrangement the entire mercury col- 

 umn was shielded from outside variations and the bulb alone was 

 in direct contact with the wood of the tree. As a still further 

 protection from precipitation and variations of the air, a tight 

 wooden box with a glass front was fastened over the thermom- 

 eter to the trunk, by means of rubber cloth and tar in such 

 manner as to be "water tight." 



The records were made at 6 to 7 a. m., 12 to 1 p. m., and 6 to 

 7 P. M., and are given in this order opposite each date in the 

 following tables: 



