28 



GROWTH IN TREES. 



This tree stood about 4 miles from the base of the mountain and the 

 instrument was transported this distance by pack animals and put in 

 action on April 4, 1918, being visited weekly until the end of October. 

 The record showed some enlargement, beginning April 14, with a 

 cambium temperature of 13 C., with readings as high as 28 C. in the 

 following 10 days. When observations were taken on April 23, the 

 temperature of the cambium was 10 C. and enlargement had ceased. 

 A slight swelling occurred May 13-20. On May 22 a shrinkage began 



13 1919 



MAY 28 1919 



FIG. 9. Dendrographic records of Chihuahua pine, with variations X 5 on 10 mm. intervals. 

 Some enlargement shown in week beginning April 15, 1919; shrinkage during week beginning 

 May 20; enlargement in week beginning May 28; daily equalizing variations of wide amplitude 

 in week beginning June 13 ; reduced variations and shrinkage in week beginning July 11 ; increased 

 variations and actual increases in diameter in week beginning August 16, and reduced daily 

 variations in late October. 



which in 6 days amounted to 1 nun., or half the total increase during 

 the previous two months. Increase began on May 28, which amounted 

 to about 2 mm. on June 14, at which time equalizing variations began 

 at tree temperatures of 23 to 27 C., which continued until June 28. 

 Now, in the extreme hot mid-summer, shrinkage began which con- 

 tinued until July 20, or until about 3 weeks after the summer rains 

 began. During this time a shrinkage of about 2 mm. had ensued, 

 which was equivalent to about three-fourths of the gain up to this 

 date. A period of increase, ending August 23, resulted in a gain of 



