GYROSTATS AND GYROSTATIC ACTION—GRAY. 199 
make the hoop to fall over to the right or the left. A bicyclist riding 
without holding the handles leans over to the right if he wants to steer 
the bicycle to the right, and to the left if he wants to steer to the 
left. And if he feels himself falling over to right or left he turns 
the handles instinctively so as to turn the bicycle to that side, when 
the machine resumes the upright position. In the bicycle, however, 
the spin of the wheels is not the most important action to be taken 
account of. 
The gyrostatic action in the bicycle is much more marked in a 
motor machine, for in that a massive flywheel rotates in the same 
direction as the wheels. As the bicycle turns a corner it is con- 
strained to precess, and a couple is needed to produce this precession 
of the rotating parts quite apart from that required to turn the rest 
of the machine. This the rider applies by leaning over to the inside 
of the turn, and leans over more than he would have to if the fly- 
wheel were not there or were not rotating. : 
Good examples of gyrostatic action are given by paddle and tur- 
bine steamers. A paddle steamer is steadier in a cross sea than a 
screw steamer of the same size. This is due in part to the gyrostatic 
action of the paddle wheels, which, but for their comparatively slow 
speed of rotation, would form a compound gyrostat of considerable 
power. For this gyrostat the spin momentum may be conveniently 
represented by a line drawn from -the steamer toward the port side. 
A couple tending to tilt the steamer over to starboard is represented 
by a line drawn toward the bow, and a couple tending to tilt the 
steamer to port by a line drawn toward the stern. Hence, if the 
steamer heels over to starboard, her bow, in consequence of gyrostatic 
action, precesses to starboard, but the starboard wheel, becoming 
somewhat more deeply immersed, uses more power and exerts a turn- 
ing influence to port. Thus the steersman has less difficulty in 
keeping the vessel on a straight course. But if the vessel be turned 
by the rudder, say to port, the vessel will by gyrostatic action be 
slightly heeled over to starboard, and the starboard wheel, being more 
deeply immersed, will assist the turning action of the rudder. When, 
however, the steamer falls off her course, to port or starboard, the 
gyrostatic action causes the correcting action applied by the rudder 
to be resisted. Though the gyrostatic action of the wheels is not 
very great, calculation shows that it is enough to produce an appr eci- 
able variation in the immersion of the wheels! 
The gyrostatic action of the flywheel in a motor ear is sof some 
practical interest. The flywheel is placed withits plane athwart the 
car—that is, with the axis, so to speak, fore and aft. It rotates in 
the clockwise direction as viewed by an observer behind the car. 
The effect of turning a corner to the left gives a gyrostatic couple 
throwing the weight of the car more on the back wheels; turning to 
