XXXviii PROCEEDINGS OF THE ROYAL HORTICULTURAL SOCIETY. 



SCIENTIFIC COMMITTEE. 



Sir J. D. Hooker in the Chair, and thirteen members present. 



Injuries to Trees by Hoar Frost. — Additional and corrobora- 

 tive information was received from Mr. Plowright, of Lynn, of 

 the remarkable occurrence, described at the last meeting, of 

 boughs of various trees being broken off by the extraordinary 

 deposit of crystals of rime upon them. As no snow had fallen 

 during the period, it was impossible to attribute the results to 

 such a cause. There had been excessive fog previous to January 7, 

 1889 ; the rime forming upon the telephone wires was so great 

 that they were broken down. The ice was deposited unilaterally 

 like flat sheets of glass, 1 \ to 2 inches in width on the south side. 

 On the 8th was a thaw. The result of the frost was that a birch 

 had a branch amounting to one-third of the tree broken off ; the 

 smaller branches particularly suffered. The elms were most 

 injured, branches of all sizes being broken off, even large arms, 

 one measuring 5 feet G inches in circumference, and 1 foot 

 10 inches in diameter. To such an extent was the roadway 

 covered with debris that the market carts were greatly impeded. 

 Oaks, willows, and poplars also suffered ; but ashes and Scotch 

 firs escaped. Several photographs and broken branches were 

 sent as illustrations of the way in which the damage was effected, 

 for Mr. Plowright noticed that fracture without falling was a 

 distinct feature of rime-injuries to trees, excepting to willows 

 and poplars, the vast majority of whose branches fell to the 

 ground. It was a remarkable sight, for example, to observe the 

 broken but still pendent branches of the oaks upon the Hillington 

 Road, hanging on them for some weeks afterwards, and all on 

 the south side. 



Mr. W. G. Smith recorded and figured in the Gardening 

 World for March 20, 188G (p. 457), a very similar occurrence 

 at Dunstable, due on that occasion to frost, fog, and wind com- 

 bined. The ice formed sheets as thin as paper, about 2 inches 

 wide, and attached to the leeward sides of the boughs, but at 

 intervals only to the wood, thus forming a series of arches. He 

 attributed this fact to the warmer temperature of the living shoots, 

 which melted the ice throughout the greater part. These blades 

 of ice were about 2 feet long. Any little extra wind caused a 

 stir among the branches like the sound of breaking glass. For 



