236 



ANNUAL REPORT SMITHSONIAN INSTITUTION, 1910. 



Table I. — Negative drop. 



[Distance between cross hairs =1.010 cm. Distance between plates == 1.600 cm. Tem- 

 perature=24.6° C. Density of oil at 25° C. =0.8960. Yiscosity of air at 25.2° C.= 

 0.0001836.] 



