1 88 1. fiY Tra7is. N. Y. Ac. Set. 



apparently perfect. However, the antennee of the crickets were remark- 

 ably long-, and seemed to guide them more than their eyes. He related 

 observations made by Prof. Putnam on the crickets, and also on the 

 crawfish from the Cave, shut up in an aquarium, which seem to indicate 

 that they judge of their food more by touch than by sight. 



Dr. Newberry had observed in an old Spanish mine in New Mex- 

 ico, millions of bats clinging to the rock, many of them with their 

 young, at a print se\eral hundred yards from the entrance. In all 

 cases such denizens of caves find ready access to the exterior atmos- 

 phere through the crevices and galleries. 



Mr. Stevens had observed bats at the same distance from the 

 entrance as noted by Dr. Trimble. In regard to the absence of fatigue 

 in traveling underground, he had found a walk of thirty miles had 

 caused no more exhaustion than one of ten miles on the surface; this 

 was probably due to the purity, coolness and dryness of the atmos- 

 phere. 



Mr. BrittON stated that a Natural Science Association had 

 recently been formed on Staten Island, having for its particular object 

 the collection and diffusion of information on all subjects relating to the 

 Natural History of the Island, and the formation of a cabinet illustra- 

 tive of its natural products. The meetings are held at New Brighton 

 on the second Saturday of each month. The ofificers of the Associa- 

 tion are : 



President Sanderson Smith. 



Corresponding Secretary, Arthur HoUick. 



Recording Secretary, Charles W. Leng. 



Curator William T. Davis. 



The address of the Corresponding Secretary is at Port Richmond. 



December 19, i88r. 

 Section of Physics. 



Vice-president, Dr. B. N. Martin, in the Chair. 

 Thirty persons present. 



A specimen of acicular hornblende in quartz was exhibited by 

 Mr. W. L. Chamberlain. 



The following paper was read by Prof. W. P. Trowbridge : 



on the determination of the heating surface required in 

 steam pipes employed to produce any required dis- 

 charge of air through ventilating chimneys. 



To ventilate a room properly requires the frequent removal ot vitiated 

 air and the introduction of fresh or pure air, the quantity, by weight, 

 of the air introduced and rejected being equal in a given time. 



