1915-16.] Fall of Small Particles through Liquid Columns. 239 
the size of particles which are of spheroidal or cuboidal form. Should the 
particles, however, be of a flat flaky form, it is doubtful if the “ effective 
radius ” calculated according to Stokes’s law can be regarded as even a first 
approximation. Flaky particles will probably descend in zigzag courses in 
varying positions with fluctuating speed. It is possible that they might be 
set in rotation like thin slips of paper in their whirling oblique fall through 
air, a problem which was discussed qualitatively by Maxwell.* 
The distribution-curve obtained in the way described would certainly 
discriminate among sets of particles with different terminal velocities. 
Some interesting results might also be obtained by finding the distribution- 
curves for the same mixture of particles falling through columns of liquid 
of different density and viscosity. 
* Cambridge and Dublin Mathematical Journal , vol. ix, 1853 ; Scientific Papers , vol. i, 
p. 115. 
{Issued separately January 16, 1917.) 
