52 TROWBRIDGE: THE THERMOMETRIC MOVEMENTS : 
tree temperatures are described and the following statement ma ide 
‘Casual observations made by one of the writers in mmid-wiall x 
showed maples frozen for a depth of an inch and a half in one case 
and an inch in another, while both white and yellow birches w 
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change of temperatures of aes tree teas and atmosphere. The bulb of the 7 
thermometer was one inch below the surface; that of the ‘‘Medium’’ three 
below; that of the “Deep” five inches below. From A to Bon the curvesall three 
temperatures were the same. Yet the frost crack decreased in width with 
general rise of temperature of the tree trunk. The mean at A was 15.4° F., ame 
°° 
frozen through, except where the sun was beating upon them. 
seems clear that some of the maple tissues are frozen in 
winter.”’ Also, as a summation, this view is given: “These 
and observations lead to the conclusion that in the winter, 
temperature of the maple tree tissues is generally below 1) 
