Page:Popular Science Monthly Volume 75.djvu/39

Rh boomerang, spinning in the direction of the arrows SS, Fig. 30, tends to climb upwards through the air. The result is that the curve of flight as shown in Fig. 30 is approximately a horizontal circle, the drooping of the curve of flight which would normally be produced by

gravity being counteracted by the tendency of the boomerang to glance upwards and the tendency of the boomerang to climb upwards as specified.

Fig. 31 represents a spinning wheel hung upon a vertical axis from a hinge which permits the axis to swing to and fro in the plane of the keel of the ship (plane of paper in Fig. 31), the lower end of the axle being guided between two parallel bars. If the spin-momentum of the wheel were sufficiently great, all rolling motion of the ship could be eliminated, and the ship would heel over into a position for which the average heeling or rolling torque would be equal to zero; thus, the