THE GYROCAR 



scopes that balanced it were about five inches in diameter. 

 It seems almost incredible that wheels so small should be 

 able to balance a car six feet in length, but it must be 

 understood that these small gyroscopes whirl at the rate 

 of about seven thousand revolutions per minute, and, of 

 course, the gyroscopic force is proportionate to the rate 

 of revolution. If we recall that a light hoop making 

 perhaps fifty or a hundred revolutions per minute 

 acquires a considerable stability, we shall cease to 

 wonder at the rigidity of the axles of the wheels revolving 

 at such enormous speed. 



The model car accomplished the feat of carrying a 

 passenger weighing about one hundred and forty pounds 

 across a little valley on a wire cable, a voyage in some 

 respects the most remarkable that any man has thus far 

 been privileged to make. The car has shown that it 

 can go up or down a sharp incline ; but this, as a mo- 

 ment's reflection will show, does not involve any change 

 of direction of the gyroscopic axle, and therefore involves 

 only the ordinary laws of mechanics. It is all one to 

 the gyroscope whether the car moves on the level or up 

 or down hill, so long as it moves straight ahead. 



Nor do the gyroscopes interfere in the least with the 

 turning of the car in passing round a curve, when the 

 two of them are linked together, as Mr. Brennan links 

 them, so that any lateral change in the axis of one is 

 balanced by an opposite change of the axis of the other. 

 With the single gyroscope, such as Mr. Brennan used 

 when he first began his experiments, the car encounters 

 difficulties at curves in the track. 



But before we can understand how the two gyro- 



