MIRACLES OF SCIENCE 



hides, the case is not quite so clear. Reference has 

 been made to Mr. Louis Brennan's gyro-car, exhibited 

 in 1907. Two years later Mr. Brennan constructed a 

 car of commercial size, capable of carrying forty or 

 fifty passengers, and clearly demonstrated the feasi- 

 bility of balancing this vehicle on a single rail with 

 the aid of his gyroscopic mechanism. Whether or 

 not the idea of a mono-rail vehicle will prove com- 

 mercially valuable remains to be seen. Mr. Bren- 

 nan's original idea was that such vehicle might have 

 utility in time of war, being operated over a tempo- 

 rary rail which could obviously be laid with far greater 

 facility than an ordinary double rail track. It is pos- 

 sible that a much more extended use may be found for 

 the mono-rail vehicle. 



In any event the demonstration of the principle of 

 balancing a land vehicle with the aid of a gyroscope 

 has great interest. The principles involved have al- 

 ready been explained, but it will be obvious that a 

 vast deal of ingenuity was required to devise a mech- 

 anism through which the principle would be sucess- 

 fully applied to the feat of balancing a car resting on 

 a single line of wheels. Mr. Brennan found the solu- 

 tion with the aid of a gyroscope with the axis placed 

 horizontally, one end of the axis being extended and 

 adjusted in such a way that it will roll along the sur- 

 face of upper and lower flanges alternately, thus ac- 

 celerating the precessional movement which would 

 be inaugurated by the tipping of the car. 



The effect, briefly, is this: The car tipping tends 

 to displace the axis of the gyroscope downward, but, 

 owing to the curious principle of gyroscope action at 



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