331 
1911-12.] On a Continuous-current Motor-Gyrostat. 
one of the authors. The motor-gyrostat is mounted, by means of two 
pivots screwed to the rim of the outer case, in two bearings carried by a 
magnalium casting in the form of a ring having a diameter slightly greater 
than that of the case of the gyrostat. Rigidly fastened to the ring at 
the extremities of a diameter, with their lengths at right angles to the 
plane of the ring, are two stiff legs terminating in points. To give rigidity 
to the legs a distance-piece is provided as shown. The line of the pivots 
is at right angles to the plane of the legs. Fastened to the top of the 
gyrostat, and in line with the axis of the flywheel armature, is a weight 
mounted as shown. 
If the arrangement is placed on a table, with the legs and axis of the 
gyrostat vertical, and left to itself, it will balance on the legs. If the 
Fig. 9. — Alternative form of Motor-Gyrostat. 
system tilts over in either direction the gyrostat precesses on its pivots so 
as to carry round the axis in a plane parallel to that containing the legs. 
But as soon as the axis of the gyrostat becomes inclined to the vertical, 
a couple, due to the weight fixed above the gyrostat, comes into play ; and 
this couple is such as to hurry the precession. The gyrostat stands up 
towards the vertical, carrying with it the ring and legs. Again, tilting 
over of the gyrostat and weight in a vertical plane (from left to right or 
from right to left in the figure) is followed by precession of the gyrostat 
about the line joining the pointed feet of the stilts. But, as soon as the 
plane of the stilts get out of the vertical, a couple due to gravity, tending 
to hurry the precessional motion, comes into play, with the result that 
the gyrostat stands up vertically as before. Hence the arrangement is 
completely stable. 
In fig. 9 an alternative design of motor-gyrostat is illustrated. For 
many purposes it is desirable that the gyrostat should be provided with an 
extended shaft which rotates with the armature, and it was to supply this 
