1853.) 315 
there this banking up of the water before it reached the rock, but there was 
also a depression alove—that is, up stream from this bank of water on the one 
hand, and below or down stream from the rock on the other. 
‘*Tn like manner it appears to me, that Herndon’s observations have revealed 
the fact that there is, at times at least, in the intertropical atmosphere of South 
America, an air-cast mould of the Andes. 
‘¢ It is remarkable how clearly these observations indicate a piling up of the 
atmosphere to the windward of the Andes, and a depression in the general at- 
mospherical level to the windward again of this air bank. If this conjecture 
afford the real explanation of the phenomena, we should look on the lea side of 
the Andes for a low barometer, or a depression in the atmosphere, corresponding 
to the hollow in the water below Pot Rock. 
“The mean height of the Bar in Lima, as far as I have been able to ascertain 
it, indicates that such a depression is felt there. 
“Tf subsequent observations should confirm these indications and establish them 
as realities, we should then be put in possession of important physical facts. 
We should be led to infer that the height of mountains, and of mountain slopes 
above the sea level, as determined by the barometer, would depend somewhat 
upon which way the wind blows,and the only safe rule of admeasurement in such 
cases, would be to establish a standard barometer at the foot of the mountains, 
both in the windward and the lea side. 
‘¢ Another of the physical facts besides that of establishing the direction of the 
wind, as a function in barometric determination is, that if this increased pressure 
of the atmosphere at the eastern foot of the Andes be caused by the obstruction 
which that range of mountains affords to the passage of the trade winds, then do 
those mountains in the trade wind region become a natural anamometer, which 
will give us in terms of the barometer an expression for the whole amount of 
force employed in giving motion and velocity to the trade winds of the earth.” 
ELECTION. 
J. Dickinson Logan, M. D., and Mr.'Frederick Schafhirt, of Philadel- 
phia, and Mr. P. W. Sheafer, of Pottsville, were elected Members of 
the Academy, and 
Dr. H. Schaum, of Berlin, Dr. G. Hartlaub, of Bremen, and Prof. A. 
Wagner, of Munich, were elected Correspondents. 
April 12th. 
Vice-President BripGEs in the Chair. 
A communication was read from the Historical Society of Pennsyl- 
vania, dated March 17th, 1853, acknowledging the receipt of the last 
number of the Journal, and of a collection of Indian antiquities pre- 
sented by the Academy. 
Mr. Conrad presented a paper for publication in the Journal, describ- 
ing new species of Unio; which was referred to Dr. Ruschenberger, 
Dr Wilson and Dr. Zantzinger. 
A second paper from Mr. Conrad was also presented, intended for 
publication in the Proceedings, entitled, “Monograph of the genus 
Fulgur.”” eferred to same Committee. 
