proceedings: bioIvOGicai, socmTv 355 



Although the accidental forces dominate the flight and necessitate 

 frequent rectification, nevertheless these tend to average out and their 

 sum to become zero. The same is true of accidental side slipping effect. 

 Therefore the problem resolves itself into finding the displacement by 

 the deflective influence when operating during the interval between 

 rectifications. 



It was shown the aggregate effect tended to carry the craft to the 

 right of it 5 course in the Northern Hemisphere by a small angular 

 amount given by the equation, 



"^60 



e = ^-~ t sm <p 

 86164 



in which t is the time in seconds between rectifications and (p is the 

 latitude. 



The angle 6 could be regarded as a compass correction and the error 

 of flight eliminated by steering to the left of any specified course by 

 the angular amount 6, values of which for different latitudes were given 

 varying from over 5 minutes of arc at latitude 20 degrees to nearly 15 

 minutes at 80 degrees. It was also shown that the linear displacement 

 from course varied as the sin'^ 6 or nearly as the square of the time be- 

 tween rectifications and in a lo-hours' flight would amount to nearly 

 5000 meters. 



While not a part of the main purpose of the paper, it was pointed 

 out that the equations lead to the deduction that gliding could be pro- 

 longed if executed in a right-hand instead of a left-hand turn of large 

 radius. Also, turning to the right when climbing is more efficient than 

 turning to the left. 



Following the second paper Mr. L. J. Briggs spoke briefly on the 

 application of certain other dynamical principles to the flight of air- 

 craft. 



S. J. MauchIvY, Recording Secretary. 



BIOLOGICAI. SOCIETY OF WASHINGTON 



The 595th regular meeting of the Society was held in the Assembly 

 Hah of the Cosmos Club, Saturday, April 5, 1919; caUed to order at 

 8 p. m. by President Smith; 55 persons present. Eight informal com- 

 munications were presented. 



W. P. Taylor: The Olympic elk, Cervus roosevelti, thought to have 

 been extirpated in Washington State outside of the Olympic Moun- 

 tains, has recently been reported from the following localities within 

 Pacific County; two bands of. 40 each on the Nasel River, one band 

 of about 50 on North River, one band of 25 on the Nemah River, two 

 small bands on the South Fork of Wallapa River, and one small band 

 on the main Wallapa River. There are said to be about 175 animals in 

 aU. 



A. S. Hitchcock: Attention called to two recent botanical publica- 

 tions, and copies of the books exhibited: Prof. J. F. Rock, A mono- 

 graphic study of the Hawaiian species of the Lohelioideae, and Prof. E. D. 

 Me;rril,Iv, Rumphius's Flora Amboinensis. 



