PROCEEDINGS OF THE THIRTY-FIRST 
ANNUAL SESSION 
Held in Grinnell, April 27 and 28, 1917 
The Iowa Academy of Science held its meeting at Grinnell 
College, with Alnmni Recitation Hall as headquarters. The first 
meeting was opened at 1:30 on Friday afternoon, the 27th, with 
President Stewart in the chair. After the business session a 
general literary session was held, following which the Academy 
divided into three sections as follows for the reading of papers 
of special interest: (1) Geology, (2) Biology and Botany, (3) 
Mathematics, Physics and Chemistry. 
In the evening at 8 o’clock Professor S. M. Woodward of the 
State • University of Iowa gave his illustrated lecture on the 
Flood Protection Plans for the Miami Valley, Ohio. 
This address is published substantially as given, in the Pro- 
ceedings of the Ohio Engineering Society — Thirty-eighth Annual 
Meeting, 1917. 
On Saturday morning the sections resumed their meetings and 
at 11 o’clock the Academy met for its final business meeting, at 
which new members were elected and officers for the ensuing 
year were chosen. 
The Iowa and Ames sections of the American Chemical So- 
ciety, and the Iowa section of the Mathematical Association of 
America held their meetings in connection with the Academy. 
REPORT OF THE SECRETARY. 
Members of the Iowa Academy of Science: 
The past year has been an active and prosperous one for the 
Academy, one of the best years, indeed, in its recent history. A 
number of scientists and friends of science have united with 
the Academy during the year. The President of the Academy 
has prosecuted a vigorous campaign for recruits to our ranks, 
and as a result of this effort coupled with the activity of other 
members, the names of over sixty candidates are to be presented 
to the Academy for election to membership. The Executive 
Committee has made a canvass of the membership roll and has 
recommended a 'large number of Associates to promotion as Fel- 
