1884. 97 Trans. N. V. Ac. Set 



have since disappeared. As the climate became severe, with the 

 approach of the Ice period, they retreated southward. As it became 

 again milder, only a few survived and once more returned. Thus, 

 the Sequoias were found fossil in numerous species, reaching to the 

 Arctic Sea, spreading over the continent in luxuriant forests, consist- 

 ing of magnificent trees, but of these only two species now survive. 



April 21, 1884. 

 Lecture P^ening. 

 The President, Dr. J. S. Newberry, in the Chair. 

 A large audience occupied the East Hall. 



Professor F. VV. Putnam, of Cambridge, Mass., delivered a 

 lecture on 



recent discoveries in the prehistoric mounds of OHIO. 



April 28, 1884. 

 Section of Physics. 

 The President, Dr. J. S. Newberry, in the Chair, 

 A large audience was present. 



Professor H. Carrington Bolton, of Hartford, Conn., read 

 the following papers, which were illustrated by many specimens : 



I. THE "singing beaches" OF THE BALTIC. 



The speaker stated that, since presenting his first paper (on March 

 loth), he had received intelligence of thirteen additional localities of 

 sonorous sand on the Atlantic coast, chiefly in New Jersey and North 

 Carolina. 



The late Dr. Meyn, in his " Geological Description of the Island of 

 Sylt," mentions briefly the occurrence of sonorous sand on the Island 

 of Bornholm, an island belonging to Denmark, in the Baltic. Since 

 the quartz sand of Sylt does not have these acoustic properties. Dr. 

 Meyn jumps to the conclusion that this quality of sand may be used 

 to distinguish that of Tertiary and of Jurassic origin. This is obvi- 

 ously an error, resulting from attempts to generalize on a single obser- 

 vation. The acoustic quality of the sand is entirely independent of 

 its geological horizon. 



Through the kindness of Professor S. F. Baird, Secretary of the 

 Smithsonian Institution, we obtained samples of sonorous sand from 

 7 



