﻿190 Dr. S. A. Shorter on the 



horizontal projection of the element. The slight variation 

 of n with time may be ascribed to the rotation of the spe- 

 cimen as a whole about a horizontal axis through the origin. 



Summary. 



The sao-o-ino- of thin uniform rods in the form of canti- 

 levers under the influence of their own weight is divided 

 into three cases, and empirical results are given for one of 

 these cases. 



The case considered is that in which plastic yielding occurs 

 and the momentum generated in the rod is insufficient to 

 cause it to swing past, and oscillate about, its final equi- 

 librium position. 



It is shown that for the thin wires used (iead, tin, and 

 cadmium), if the origin be taken at the encastre end, the 

 equation to the curve they assume is of the form x = ay n . 



The significance of the terms a and n is discussed. 



In conclusion it affords the writer much pleasure to 

 express his thanks to Professor A. W. Porter, F.R.S., for 

 his kindly interest in this paper. 



XX. On the Shape of small Drops of Liquid. 



To the Editors of the Philosophical Magazine. 



Gentlemen, — 



N the November number of the Philosophical Magazine 



i 



Mr. J. Rice puts forward a theory to account for the 

 peculiar shape (a biconcave disk with rounded edges) of the 

 red corpuscles of blood and of suspended particles in a 

 lecithin emulsion. Now experiment shows that small par- 

 ticles of liquid suspended in another liquid always assume 

 a spherical shape — as is to be expected from considerations 

 of surface-tension. Hence the most natural explanation of 

 the above shape is that the effect of surface-tension is 

 modified by some other factor or factors. Mr. Rice, however, 

 assumes that the peculiar shape is due to surface-tension, and 

 attributes the deviation from sphericity to the smallness of 

 the particle and consequent variability of the surface-tension. 

 Assuming- that the surface-tension T at any point is a 

 function of the thickness of the disk at that point, Mr. Rice 



