Febbuaey 7, 1902.] 



SCIENCE. 



231 



which was connected by means of capillary 

 copper tubing to a series of cells similar to 

 those used in the construction of aneroid 

 barometers. The bulb, tube and cells, were 

 filled with oil and the recording mechanism 

 attached to the aneroid cells. 



F. L. Tufts, 

 Secretary. 



PHILOSOPHICAL SOCIETY OP WASHINGTON. 



At the 545th meeting, held on January 18, 

 1902, Mr. L. P. Shidy, Chief of the Tidal Di- 

 vision, Coast and Geodetic Survey, gave a 

 brief 'Explanation of the Currents in Unalga 

 Pass, Aleutian Islands, Alaska.' Dr. Dall 

 spoke of the difficulties of navigation in this 

 pass when there is a strong current, and of the 

 unaccountable dying away of the wind near 

 the center of the pass. 



He said that these currents seem to conform 

 to Torricelli's theorem for the flow of liquids 



If we extract the square root of 2g, we have 

 7=8.0215 Vd feet per second, 

 or converting this into nautical miles per hour, 

 it becomes 



7=4.75 ^d knots, 



in which d is expressed in feet, as before. 



The tides at each end of Unalga Pass were 

 tabulated in the accompanying table. 



The computed velocities of the current in 

 the given table were obtained by the applica- 

 tion of Torricelli's theorem. It may be re- 

 marked that there is, in general, a satisfactory 

 agreement between the observed and com- 

 puted velocities. The times of changing direc- 

 tion of flow are correctly given by computa- 

 tion, and the interesting phenomenon which 

 occurred at 16 hours on June 14, 1901, where 

 the southerly current had decreased to 1 knot, 

 and then increased again without reversing 

 its direction, is reproduced by computation 

 within small limits of error. 



due to a difference of head, which may be ex- 

 pressed thus : , 



V=y2gd feet per second, 



where g=S2.1T22 feet=the velocity of a fall- 

 ing body at end of first second, and (i=the 

 difference in feet between the elevation of the 

 water surfaces at each end of the strait. 



Professor J. H. Gore gave an account of the 

 proposed 'Draining of the Zuider Sea,' illus- 

 trated by many lantern slides. The old plans 

 have been found commercially impracticable, 

 and the plan definitely recommended by a 

 large Commission appointed in 1892 is the fol- 

 lowing : Only those portions are to be reclaim- 

 ed that have a clay bottom; this leaves free 



