The electron, its isolation and measurement and the determination of some of its properties

by Robert Andrews Millikan

, which encircles the condenser plates

and

. Through the third of these windows, set at an angle of about 28° from the line

and in the same horizontal plane, the oil drop is observed through a short-focus telescope having a scale in the eyepiece to make possible the exact measurement of the speeds of the droplet-star.

In plotting the actual observations I have used the reciprocal of the pressure

in place of