EXPERIMENTS ON THE DEVIATIONS OF FALLING 



BODIES. 



By Edwin H. Hall. 



Presented June 17, 1903. Received November 14, 1903. 



This paper is a supplement to one recently published in the Physical 

 Review * under the title, " Do Falling Bodies move South ? " It will 

 give some account of the preliminary experiments and variations of 

 method which the author made in the course of his study of the behavior 

 of falling bodies, and will discuss to some extent sources of possible error 

 in the result arrived at; a result which is in favor, so far as it carries 

 weight, of an affirmative answer to the question stated above. It is 

 unlikely that such details as are here to be given will interest any large 

 number of readers, but they may be of considerable value to any in- 

 vestigator who may hereafter occupy himself with this still unsettled 

 question. 



Cajori remarks that all experimenters in this research have used metal 

 balls, and therefore I, desiring to vary the conditions, undertook at first 

 to use spheres of ivory, about 2.54 cm. in diameter. They were made 

 by a manufacturer of billiard balls, and were, presumably, good speci- 

 mens of workmanship iu ivory, but under the calipers they showed them- 

 selves not to be true spheres, differences of diameter along different axes 

 being very perceptible, as large, perhaps, as 0.01 cm. A number of ex- 

 periments were made in dropping these balls ; but they were so erratic 

 in their fall that I felt obliged to give up the hope of getting any valu- 

 able result from them, and I therefore resorted to balls of bell-metal, 

 which, to my surprise, I found already in the hardware market, almost 

 perfect in form. 



It now seems probable that the unsatisfactory performance of the ivory 

 balls was in part due to a cause which at first gave me much trouble in 



* Part I., Historical, in September, 1903; Part II., Methods and Results of the 

 Author's work, October, 1903. 



