Harshberger on Relation of Ice Storms to Trees. 347 



observations made by the writer, the forest and shade trees 

 seemed to be injured in the following order: i, silver maple 

 most injured; 2, weeping willows; 3, Carolina poplars; 4, 

 beeches ; 5, elms ; 6, hickories ; 7, white oaks ; 8, plane trees, 

 especially the oriental species; 9, Kentucky coffee tree, 

 almost not at all; 10, coniferous trees, pines, etc., not at all. 



At Horticultural Hall, Mr. John J. Prentzel recorded that 

 a branch of an oriental plane tree, broken off encased in ice, 

 weighed fifty-six pounds, and that after the ice had been 

 melted off, it weighed nine ounces; a ratio of about i : 100. 

 Dr. Swartzlander,* of Doylestown, Bucks County, Pa., 

 weighed a twig with ice on and it weighed fifteen pounds. 

 After melting the ice, the twig weighed nine ounces, a ratio 

 of I : 26. Mr. H. H. Chapman^ gives an account of the 

 effect of this storm on Staten Island. The trees observed 

 were elm, beech, tulip poplar and black oak, which had 

 sound limbs broken that were four inches or more in diame- 

 ter. White oak alone, according to Chapman, seemed to 

 resist serious damage by the greater strength of its branches. 

 To calculate the force which caused such destruction, twigs 

 were cut transversely and diagrams made of the thickness of 

 twig and ice incrustation. Calculating from the relative 

 area in cross section, it was found that twigs one-eighth 

 inch thick were carrying thirty to forty times their weight. 

 In addition to this heavy weight, the trees were subjected 

 to high winds, so that in many cases the crowns of trees 

 were reduced fully go per cent. 



The second storm of Saturday, December 13, 1902, gave 

 the writer an opportunity to test the facts recorded above 

 and also to ascertain additional facts of moment. Seven- 

 teen species of trees and shrubs growing in the Botanic 

 Garden of the University of Pennsylvania, afforded material 

 for study. The plan pursued was to cut off a limb, usually 



* Forest Leaves, VIII. October, 1902, p. 168. 



'Forestry and Irrigation, VIII, 1902, p. 130; also Experiment Station 

 Record, XIII, p. 1053. 



