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 
eut 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 eut 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: 
