Prof. Silliman on an ewtraordinary Avalanche. 299 



These temperatures were determined by a small thermome- 

 tric bulb terminated by a very short capillary tube filled with 

 mercury at a determinate temperature, (that of melting ice for 

 example.) This bulb was plunged into the melting alloy, and 

 when the mercury which run over it was removed, it was carefully 

 weighed. The results of these weighings were calculated after 

 the experiments of M. Dulong, and consequently give the tem- 

 peratures immediately in degrees of the air thermometer. 



The preceding article is a very general abstract of the 

 original, which is published in the Ann. de Chim. tom. xl. 

 p. 285—302. 



Art. XIV. — Contributions to Physical Geography. 



1. Account of an extraordinary Avalanche in the White Moun- 

 tains of New Hampshire^ which took place on the 28th Au- 

 gust 1826. By Professor Silliman, Rev. C. Wilcox, and 

 Mr T. Baldwin.* 



The whole day's ride, in an open waggon, has been in the 

 winding defile of mountains, which probably have not their 

 equal in North America, until we reach the Rocky Mountains. 

 The portion of the Notch which is the grandest, is about five 

 or six miles in length ; it is composed of a double barrier of 

 mountains, rising very abruptly from both sides of the wild 



* Abridged from Professor Silliman's Journal of Science, vol. xv. No. 



2, p. 216—233. Jan. 1829. 



