508 E. P. TAYLOR. 
(b) The other six tests were made with a known brake 
torque applied to the flywheel for determination of 
the moment of inertia. 
(c) Six more runs were then made after removing the 
connecting rod and, consequently, the piston. 
(d) After the layshaft was removed, five more runs were 
made with the main bearings only left to produce 
friction. 
And as each part was replaced on the engine, 
checking runs were made again. 
The procedure in each test was to run the engine up 
above normal speed when possible, and then cut off the 
driving source, leaving the engine free to run down under 
only its own friction. This could be done only in the case 
of the Victor and Crossley engines. In the case of the 
National engine the relatively small extra friction due to 
the coupled generator was allowed for afterwards. 
While the engine was slowing up, a contact maker on the 
engine shaft completed an electric circuit for an instant 
every revolution. In this circuit was a small electro- 
magnetically-operated stylus which recorded on a smoked 
paper every revolution of the engine. The chart revolved 
at a regular rate so that the number of kicks in a certain 
length of chart gave a means of measuring the speed of the 
engine at any instant. 
Asa check, and also to facilitate the working out of the 
velocities, another stylus actuated every second from an 
independent clock, was caused to mark seconds just beside 
the revolution line. After flxing this smoked chart ina 
very weak solution of shellac, a velocity-time curve was 
drawn from it, and from this curve the retardation of the 
engine was determined at several speeds by drawing 
tangents at the points representing those speeds. 
