,
per cubic centimeter of gas passing, minus the weight per cubic centimeter of saturated water vapor, gives the weight of the cloud per cubic centimeter. This completes the measurements involved in (2) and (3), [p. 47.]
As to (4), [p. 48], the average size of the droplets of water Townsend found by passing the cloud emerging from
into a flask and observing how long it took for the top of the cloud to settle a measured number of centimeters. The radius of the drops could then be obtained from a purely theoretical investigation made by Sir George Stokes,[198] according to which the velocity
of fall of a spherical droplet through a gas whose coefficient of viscosity was
is given by