522 
PHILOSOPHICAL SOCIETY OF WASHINGTON. 
was presented showing that each station gave a diminution of rainfall 
during the latter half of the long period. This was due to the fact that 
the secular variation reached a minimum about 1877 and the forest had 
little or no influence. The forestry reports from Illinois show, in the 
region covered by their records, about- three trees to the acre, which indi¬ 
cates plainly that they had no effect on the precipitation one way or the 
other. We may consider that forests keep back the precipitation from 
rivers, increase the humidity and the number of springs, and by actual 
observation augment the rainfall slightly, and hence should be carefully 
conserved all over the country. 
Mr. Gilbert read a paper upon the Problem of the Soaring of 
Birds. [Abstract published in Science , vol. 12, p. 267, December 
7, 1888.] 
326th Meeting. December 8, 1888. 
By courtesy of the trustees of the Columbian University the 
meeting was held in the lecture-room of the University build¬ 
ing. About 200 ladies and gentlemen were present, including, 
by special invitation, members of the various scientific societies 
of Washington and members of the Cosmos Club. 
Vice-President Eastman presided. 
The retiring President of the Society, Colonel Garrick Mal- 
lery, presented an address bearing the title Philosophy and 
Specialties. [Printed in full upon pages 3-40 of this volume.] 
327th Meeting. December 22, 1888. 
EIGHTEENTH ANNUAL MEETING. 
The President, Mr. Mallery, in the chair. 
Thirty-five members present. 
The minutes of the 310th, 325th, and 326th meetings were 
read and approved. 
The Chair announced the election and acceptance of member¬ 
ship of Daniel Currier,. Chapman. 
The report of the Secretaries was read and accepted. 
