sion is opposed by a moderate frictional torque, damping of the amplitude of roll is produced. The amount of damping would be maximum if the torque opposing precession at each instant were proportional to the speed of precession at that instant. Steering is not affected by a gyro-wheel with vertical spin-axis. The period of roll of the ship is decreased, (Art. 86).
A gyro-wheel spinning about an athwartship axis and capable of rotating about an axis AA' perpendicular to the decks of the ship, Fig. 112, will precess back and forth about this axis as the ship rolls from side to side. As in the case of the gyro with vertical spin-axle, the amplitude of roll of the ship will be damped if the precessional motion be opposed by a frictional torque.
Suppose the direction of spin is that represented by the line hs, Fig. 113. Then while the ship is rolling to starboard with angular velocity represented by the symbol w, the gyro-frame and ship will be subjected to a torque about an axis perpendicular to hs and w in the direction represented by the line L, (Art. 36). Owing to this toraue the shin steers to starboard. Similarly a roll to