1888. ] NEW YORK ACADEMY OF SCIENCES. 118 
key to several photographic problems, such, for instance, as the 
determination of the comparative efficiency or individual equation 
of lenses, and the proportionate exposures of various shutters. 
The present contribution must terminate with acknowledg- 
ments to several members of the Brooklyn Academy of Photo- 
graphy for valuable assistance in promoting the advent of a 
method which appears susceptible of refinement 1n an eminent 
degree, yet for many practical purposes seems even in its crudest 
form to afford a sufficiently accurate measurement of an instan- 
taneous exposure. 
Remarks were made by Mr. P. H. Dupiey and Mr. WILLIAM 
BARCLAY PARSONS. 
January 23, 1888. 
STATED MEETING. 
The President, Pror. J. S. NEwBERRY, in the chair. 
A fair audience present, in the East Lecture Room of the 
Library Building, Columbia College. 
The first lecture of the Popular Lecture Course was delivered 
by 
Pror. W. LECONTE STEVENS on 
THE DEVELOPMENT OF AERONAUTICS. 
(Illustrated with lantern views. ) 
January 30, 1888. 
STATED MEETING. 
Mr. CorNELIUS VAN BRUNT in the chair. 
Thirty-five persons present. 
Pror. J. 8S. NEWBERRY presented a paper’ on 
TRIASSIC PLANTS FROM HONDURAS. 
In 1886, Mr. Chas. M. Rolker, a mining engineer and grad- 
uate of the School of Mines, brought from the vicinity of San 
‘In the absence of the author, the paper was read by Dr. N. Lz 
Britton. 
