Evaporation from Trees in Winter. 13 



This subject of moisture loss from dormant trees 

 seems to be a most important one, and it is strange 

 that the matter seems to have escaped the attention 

 of pomologists. In order to spread a knowledge of 

 the subject, further studies in the evaporation from 

 winter twigs have been made for me by my stu- 

 dent, A. L. Knisely, M.S.: 



"In January, 1897, I cut twigs of various kinds 

 about one foot in length, and took them to the lab- 

 oratory. When ready to weigh the twigs, they were 

 cut down to about four or five inches in length, the 

 object of the second cutting being to leave as little 

 time as possible between the cutting of the twigs and 

 the weighing. As soon as the short twigs were cut, 

 they were weighed, and the freshly cut ends were 

 then dipped in melted paraffine, thus sealing the cut 

 surfaces and preventing evaporation except through 

 the bark and buds of the twigs. After dipping in 

 the paraffine, they were weighed again, and then put 

 in places as much exposed as were the trees from 

 which they came ; in fact, in some cases, the twigs 

 were tied on the trees and left there for 72 hours, 

 and then weighed. They were afterward exposed for 

 another 72 hours and weighed again, making a total 

 length of time of 144 hours, or 6 days, that the twigs 

 were exposed. During all this period, the thermome- 

 ter registered below the freezing point. That there 

 is loss of moisture by evaporation is shown by the 

 following table, which gives the data obtained from 

 the twigs of a number of our most common fruit 

 and shade trees: 



