von Schrenk — A Severe Sleet-storm. 147 



In weighing the branches short pieces were taken ; usually 

 the twigs were about three years old, although several were 

 older branches. It would obviously be unfair to compare a 

 branch \ inch in diameter with one 2 inches in diameter, 

 both covered with the same thickness of ice. The branches 

 weighed were about 2 feet long and \ inch in diameter. 

 The figures in the table must be considered as purely relative ; 

 they are intended to show merely that the weight borne by 

 the smaller branches was a very large one, and to give some 

 idea of the amount which three-year-old branches can bear 

 without breaking. 



From the table it appears that different twigs had different 

 amounts of ice, as was to be expected, for no two twigs are 

 alike in form or position. Twigs on the outside of a tree had 

 more ice to bear than those more or less protected on the in- 

 side. The twigs with icicles usually bore twice as much ice 

 as those without. The deciduous trees had approximately 

 similar amounts to bear ; the differences in the table are to 

 be accounted for by differences in position. The conifer- 

 ous trees had greater weights of ice than the others. The 

 closely packed leaves of these trees were frozen into solid 

 masses, making a most picturesque sight. The ice-mass 

 steadily increased, because of the large surface exposed to the 

 rain. The small branches of such trees as pine and hemlock 

 had an unusually heavy weight to carry, and were bent, often- 

 times so as to hang vertically. The hemlock had the greatest 

 weight to bear, followed closely by the white pine. 



The weight of the smaller branches had to be borne by 

 the larger ones, and where these were not very flexible they 

 broke off at the weakest point. There was no regularity as 

 to the point at which the break occurred ; it took place near 

 the insertion of a branch and at all points towards the 

 periphery of a tree. Knots and old wounds, made by the 

 tornado of 1896, were the weak spots. A fine birch in 

 the Botanical Garden, whose trunk had been twisted 

 by the tornado, had recovered and almost healed. 

 It was snapped off like a straw at this weak spot. 

 The arbor vitae {Thuja occidentalis) is a tree whose 



