1911-12.] On a Continuous-current Motor- Gyrostat. 
321 
XXIII. — On a Continuous-current Motor-Gyrostat with accessories 
for demonstrating the Properties and Practical Applications of 
the Gyrostat. By James G. Gray, D.Sc., Lecturer on Physics in the 
University of Glasgow ; and George Burnside, Mechanical Assistant 
to the Professor of Natural Philosophy in the University of Glasgow. 
(Read May 6, 1912. MS. received July 8, 1912.) 
No branch of dynamics or physics provides a more profitable or interesting 
subject of study to the student of physics or engineering than that which 
deals with the phenomena presented by spinning-tops. Within the last 
few years the most interesting form of top, namely the gyrostat, has 
advanced from being a piece of lecture-room apparatus, or a toy, to a 
position of great practical importance. In the dirigible torpedo, Brennan’s 
monorail car, the Schlick device for rendering a ship steady at sea, and in 
the gyrostatic compass, the results are obtained by utilising the properties 
of the gyrostat. Undoubtedly, too, the gyrostat is destined to play an 
important part in many inventions still to be brought to light. 
But, quite apart from the important part played by the gyrostat in 
practical affairs, the study of spinning-tops is well worth while pursuing 
for its own sake. To be effective, such study should not be confined to the 
mathematical treatment of the phenomena ; lectures should be accompanied 
throughout by experiments carried out with actual tops and gyrostats. 
Unfortunately, the gyrostatic apparatus available up to the present time is 
the reverse of satisfactory, and experiments carried out by means of it are, 
even when the experimenter possesses great skill and experience, far from 
being effective. 
The gyrostat, or gyroscope, in its simplest form consists of a heavy fly- 
wheel mounted in a suitable framework. If the gyrostat is to be effective 
the flywheel or rotor must have a large moment of inertia, the framework 
in which the flywheel rotates must be light, and means must be provided 
of spinning the flywheel with great angular velocity. In gyrostats, as 
constructed by instrument and toy makers, up to the present time, the 
spinning body consists of a heavy wheel whose axis terminates in steel 
pivots which revolve in steel or brass bearings carried in the frame. The 
spin is obtained by the* ancient device of passing one end of a string 
through a hole in the spindle of the wheel, winding up the string on the 
spindle, and then drawing it off by the application by hand of a large force 
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