ACADEMY OP SCIENCES. 127 



Prof. Davidson mentioned that similar difficulties in France had 

 been overcome by heavy walls built so as to have a foundation be- 

 low the drifting sand. 



Prof. Bolander thought that protection might be given by plant- 

 ing such trees and shrubs as can grow in the sand and bind it by their 

 roots, mentioning several such, native or easily naturalized. 



Prof. Davidson said that the sand sometimes changed level fifteen 

 feet in a single night, so that such roots would be no protection. 



' Dr. Blake suggested the growing of annuals of dense growth to 

 give firmness to the surface until larger plants could become rooted- 



Prof. Davidson made some remarks on the habits of whales not 

 mentioned in Capt. Scammon's book. He said that the Thrasher 

 Shark would manage to ride on the whale's head and keep it under 

 water, or stop its breathing holes until it was suffocated. He also 

 said that on " sounding " in shallow water, the whale came up 

 stunned, giving the whalers a chance to strike it again, which made 

 the hunt in such seas the best. 



Prof. Bolander mentioned some new fresh-water plants found by 

 him in the Sierra Nevada, which he proposes to describe for pub- 

 lication. He also mentioned that land slides were now common in 

 the coast ranges on account of difference in the soil from that of the 

 Sierra Nevada, and not on account of the action of frost alone. 



Prof. Davidson stated that the angle of the piece of rock sup- 

 posed to be basalt by Dr. Stout was 140°, which would make a 

 nine-sided prism. 



Prof. Whitney stated that no basalt had been found within San 

 Francisco County by the Geological Survey. 



Regular Meeting, July 18th, 1870. 

 President in the Chair. 



Henry Hemphill was elected a resident member. 



The resignation of Islr. Eloesser, as Cor. Secretary, was received, 

 and an election to fill the vacancy was held, resulting in the choice 

 of Henry G. Hanks. 



