CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL 

 LABORATORY, HARVARD UNIVERSITY. 



AIR RESISTANCE TO FALLING INCH SPHERES. 



By Edwin H. Hall. 

 Presented January 12, 1910; Received January 12, 1910. 



In 1903 1 I published an account of experiments which I had made 

 with falling bronze spheres, one inch in diameter, in the tower of the 

 Jefferson Physical Laboratory. The especial object of these experi- 

 ments was to look for a southerly deviation, from the plumb line 

 vertical, of the course of the falling balls, several observers, from the 

 time of Hooke, 1680, to Rundell, 1848, having reported finding 

 such a deviation, though Gauss and Laplace, both of whom discussed 

 the matter theoretically about 1803, could find no cause for the 

 phenomenon. 



The general mean of the deviations observed by myself in the 

 north and south plane in the experiments referred to, experiments 

 much more careful and extensive than those which any one else had 

 made in this matter, was a southerly movement of about 0.005 cm. in 

 a fall of about 23 m. The probable error was about 0.004 cm., and I 

 should have regarded the case as practically closed in favor of the 

 negative if my predecessors had not, almost without exception, reported 

 a considerable southerly excursion. On the whole I was disposed to 

 try the question further, and accordingly applied in 1904 for permis- 

 sion to make experiments for this purpose in the great monument at 

 "Washington, D. C, where a sheer fall of about 165 m. is possible. 

 The monument is in the care of the War Department, and at first the 

 authorities applied to acted favorably upon my petition. A few months 

 later, and before I had made any overt preparations for the work pro- 

 posed, some change of management or of mind occurred in the Depart- 

 ment, and the permission previously granted me was courteously but 

 firmly withdrawn, " for the reason that the monument was designed 

 as a memorial to General Washington." I have long since come to 



1 Physical Review, 1903, 17, 179 and 245; These Proceedings, 1904, 39, 

 339. 



