GENERAL MEETINGS. 
9 
Florida, of Capt. Edward Phelps Lull, U. S. N., a member of 
this Society. 
The President also announced that Mr. Herbert Couper Wil¬ 
son had been elected to and had accepted membership in the Society. 
Mr. G. E. Curtis read a paper on 
THE THEORY OF THE AVIND-VANE. 
[This paper appeared in the American Journal of Science, 3d series, 8°, 
New Haven, 1887, July, vol. 34, pp. 44-52. It has also been reprinted in 
the American Meteorological Journal, 8°, Ann Arbor, Mich., 1887, Sep¬ 
tember, vol. 4, No. 5, pp. 215-224.] 
Mr. H. A. Hazen thought that Mr. Curtis’s formulse showed 
that a single-tailed vane is more sensitive than a doubled-tailed one 
and Avould define a sensitive vane as that one Avhich most quickly 
assumes the direction of the Avind. 
Mr. Bates regarded these formulae, presented by Mr. Curtis, 
Avhich had been deduced for inelastic fluids moving in right lines as 
inapplicable to elastic fluids moving in curved lines and often 
affected by vortices. 
Further remarks were made by Messrs. Abbe, Woodavard, and , 
Curtis. 
Mr. C. F. Marahn made a communication on 
THE electrometer AS USED IN OBSERVATIONS OF ATMOSPHERIC 
electricity, 
exhibiting in connection Avith it a diagram and the instrument 
itself. 
Mr. Bailey Willis made a communication on the 
development of a perspectia^e map from a contour map, 
illustrated by three sketches and diagrams. 
Mr. W. D. Johnson exhibited and explained a new plane table, 
presenting a number of improvements, especially as to increased 
stability, compactness, levelling, and mode of attaching the paper 
to the board. 
