PHENOMENA OF PLANT-LIFE. 51 



the bursting of the lead pipes and the breaking of the glass 

 tubes during severe cold weather by the formation of ice 

 within the gauges. To avoid this as much as possible, the 

 gauges were enclosed in wooden cases, and the more exposed 

 portions wrapped in woollen blankets. 



Mercurial gauges were attached to the following species, 

 viz. : sugar maple, red maple, black, yellow, white and paper 

 birches, ironwood, apple and grape, and all the observations 

 may be found in the appended tables. The general results 

 correspond with those of last year, but are much more com- 

 plete, especially in regard to the two species which exhibit 

 the most surprising phenomena and in which the public feel 

 the deepest interest, namely, the sugar maple and the grape 

 vine. 



As soon as the discovery was made, by means of the water 

 gauge, that the apple would flow from the root, a mercurial 

 gauge was attached to a root an inch in diameter. At first, 

 on the fifteenth of May, there was a slight suction amounting 

 to -1.59 feet of water ; but the pressure soon began, and rose 

 to its maximum, May thirty-first, when it equalled 15.07 feet 

 of water. Thus, the extreme variation was 16.66 feet. 



The butternut had a range of only 13.03 feet, the minimum, 

 -0.79 foot, occurring on April tenth, and the maximum, 12.24 

 feet, on April fourteenth. 



The red maple attained its minimum, -2.83 feet, April six- 

 teenth, and its maximum, 18.59 feet, April eighth, the total 

 variation being 21.42 feet of water. 



The ironwood exerted its greatest suction on the nineteenth 

 of May, which equalled -24.60 feet, while the greatest pressure 

 was 40.35 feet, and was observed, May thirteenth. The total 

 variation was thus 64.95 feet of water. 



The white birch began early in the season, April ninth; 

 reached its minimum, -19.26 feet, on the eleventh of May, and 

 its maximum, 39.66 feet, April twenty-third. The extreme 

 variation was, therefore, 58.92 feet of water. 



A gauge was attached to a root of white birch on the eighth 

 of April; the pressure began, April twelfth, and steadily ad- 

 vanced to its highest point, 38.08 feet, May twelfth, and 

 declined to zero, May twenty-third, and to its minimum, 

 -22.98 feet, August twenty-sixth, the extreme variation 



