TVials of Traction- Engines at JVolverhampfon. 550 
will of course be very great. This may be made clear to the eye 
by constructing two diagrams. Fig. 15 shows a diagram froni an 
expansive engine with a non-jacketed cylinder; the black ^lines 
Fig. 15. — Indicator Dtajram from an Expansive Engine ivith a Non- 
Jacketed Cylinder. 
Fig. l(}.—Indicaior Diagram from an Expansive Engine loith a 
Jacketed Cylinder. 
a. h 
the curve given by the indicator, and they would appear to repre- 
sent that while no greater quantity of steam than was equal to the 
space contained in the parallelogram abed, namely, one-fourth of 
the stroke of the engine by 105 lbs. high, had been consumed, the 
