September, 1S44.] S9 



the Navy to examine the several plans of floating docks 

 submitted to the Department. From Prof. Johnson. 

 Boston Journal of Natural History. Vol. 4. No. 4. From 

 the Boston .Society of Natural History. 



A letter was read from Mr. Haldeman, dated August 19, 

 1844, accompanying a series of letters addressed by the late 

 Mr. Say to the late Rev. J. F. Melsheimer, and presented to 

 the Academy by his brother, Dr. F. E. Melsheimer. Also a 

 paper by the latter, containing additional descriptions of N. 

 American Coleoptera; which, on motion, was referred to the 

 committee appointed on his former paper, read August 6th 

 last. 



Professor Johnson then offered some remarks on the speci- 

 mens of rocks presented by him this evening. 



Those from the summit of Mount Washington are quartz, coarse 

 granite, and tourmaline, with quartz filling its fissures, and plates 

 of mica adhering to its crystals. Those from the northwestern 

 slope of the same mountain are hornblende, and tabular masses of a 

 micaceous rock, in which the folia are laid in narrow bands ob- 

 liquely inclined to each other. All these materials are very durable 

 in their nature, and suffer little from mere atmospheric influence. 

 In strong contrast with these are many of the rocks found at the 

 White mountain notch. The latter are generally more or less 

 friable in their nature, and liable to pretty rapid detrition. They 

 consist of beds of gneis, intermixed with others of a granitoid cha- 

 racter, having the aspect and constituents of granite, but the loose- 

 ness and friability of gneis which has been long exposed to the 

 weather. The hardest specimens obtained from thst part of the 

 notch which contains the celebrated Willey house, are mixtures of 

 quartz and serpentine. 



A portion of the masses having a granitic aspect has since the 

 catastrophe which happened to the Willey family about 18 years 

 ago, become completely disintegrated, and fallen into small gra- 

 nules. 



The event just alluded to seems to furnish, to a considerable ex- 



