On the resistance of air

The great mass of work, both theoretical and experimental, which has been done on this subject may be divided into two classes, one of which com­prises all the results having reference to such moderate velocities as can be obtained with artificially produced currents (i. e., up to about 100 f. s.), while the other is confined to velocities about and exceeding the velocity of sound. Between these two there is a gap in the experimental record extending over a range of nearly 1000 f. s. I am not aware that any attempt has been made to connect theoretically the experimental results at high and low velocities, and it is the object of this paper to find an expression which will represent the resistance generally.