ELASTIC RADIAL DEFORMATIONS OF FLYWHEELS. 269 
4. Six armed wheel with straight arms. 
5. Four armed wheel, straight arms, jointed midway 
between the arms. 
6. Four armed wheel, straight arms, jointed along 
the arms. 
Hach wheel was approximately two feet in diameter. 
The wheels were arranged horizontally for convenience of 
measurement, and were supported on a vertical steel spindle 
1°5 inches in diameter, with a taper of 1 in 20 at the top 
end where it enters the boss of the wheel. The spindle 
rests at the bottom on an adjustable conical steel pin with 
hardened point (see fig. 1). This pin is immersed in an oil 
bath, cast into the lower part of the cast iron frame. The 
pin may also be oiled by means of a slantwise channel 
drilled into the lower end of the spindle. At its upper end 
the spindle passes through a bearing consisting of a brass 
bush, fixed in the upper portion of the frame. This bush 
is coned on the outside and has a nut at top and bottom 
for adjustment. To allow of this adjustment, the bush is 
cut into by six vertical saw cuts to within an eighth of an 
inch of its surface of contact with the spindle, in five of 
them, and completely through at the sixth. These cuts 
allow the bush to contract on to the spindle as the upper 
nut is tightened up. 
Immediately below the brass bush, a steel collar is 
attached to the spindle in order to prevent any vertical 
motion. On the spindle below this collar is a double cast 
iron grooved driving pulley. Attached to the underside of 
the boss of the wheel by means of two ; inch set screws, 
is a flat steel cross-bar + inch thick, 1} inches broad, and 
143 inches long, with two 4 inch steel bars 3 inches long at 
the ends. To these bars were attached the shackles which 
were used in the earlier experiments for the purpose of 
holding the distance rod in position. 
