81 
of the race being held in a cage (D) that-is clamped inside the balanced 
arm (E). Near the extremities of the balanced lever are inserted knife 
edges that are on a line drawn through the center of the rotating spindle, 
and the weights used were suspended from these knife edges, as shown. 
A dash-pot (H) was used to check the vibration of the lever; and the 
tendency of the lever to rotate, due to friction with the revolving spindle, 
was measured on a scale (G). 
The method of operation was to first bring the lever nearly to balance, 
leaving a slight excess weight on the scale side, then on causing the 
spindle to rotate there was an additional pull on the scale arm, due to the 
friction of the moving parts. This additional pull, when reduced to the 
ball path on the part (c), could be used to find the coefficient of friction. 
The following table will show the form of log kept: 
BALL-BEARING FOR ONE INCH SHAFT. 
(Oil Used.) 
Weight Wei : 0 
ght. Rey. Time. Coefficient 
No. oniSeals, Pounds. Spindle. Seconds. Heat. F. 
it A 90 256 | 30 INomecto. oa 0017 
8 i, 90 442 30 INone;nccess 0017 
9 % 90 | 757 | 30 INOMe.. cea. 0026 
6—SCIENCE. 
