LXXXVI. HERBERT E, ROSS. 
meter were however, taken separately for each test by means of 
mechanism to be described. 
The speed recording apparatus consisted of a small case (L) 
containing a pair of clockwork indices each indicating revolutions 
and fractions from 1 to 1,000, and driven by cords from the driver 
and driven shafts, which were dimensioned to give the same read- 
ings on each index at a low belt tension without load. The case 
also contained a split seconds stop watch, the watch and counters 
were simultaneously started or stopped by the rising or falling of 
a lever. 
A small 10 volt dynamo was attachéd to the traversing frame, 
and was driven by a small 2” friction pulley bearing against the 
rim of the driven pulley. The current from this dynamo excited 
an electro magnet in the recording box and supported a soft iron 
yoke, and the lever was supported till the yoke fell by cessation 
of the current. 
The obvious effect of any slip of the belt was a reduction of the 
speed factor in the brake friction; the brake, unable to lift the 
trussed lever with the same energy, allowed the lever to be forced 
downwards by the air in the air chamber and thus additional 
pressure was communicated to the tension cylinder (G) causing 
the brake to seize the pulley fast. The operation when slip 
occurred being practically instantaneous. The cessation of the 
current consequent terminated the speed and time records. It 
was found possible to increase the load from nil to twenty horse- 
power in a space of 10 (ten) seconds, to count the revolutions and 
accurately take the duration in that time. To remove any effects 
of momentum however, the load was distributed over about sixty 
seconds, and the recording apparatus put in motion during about 
the last twenty seconds of the test. The pulleys used were 30" 
diameter and 12” flat turned face, and were such as are ordinarily 
used in mill gearing. 
The application of fluid pressure to the automatic control of 
the brake in place of the compound differential levers on similar 
