590 TJie Trials of Light Portable Motors at Plymouth. 
it. There is no doubt, however, that the engine friction on this 
small, light, and quicker running engine was less than in the 
others. 
The Judges were decidedly of opinion that the wettest 
steam was that supplied to Messrs. Turner's engine. This is 
distinctly shown by the large cylinder condensation, which will 
be alluded to presently, and is consistent with the fact that the 
boiler of this engine was more forced than either of the others. 
That the steam used per indicated horse-power was slightly 
greater on the Turner engine than in the Adams engine was no 
doubt due to this greater initial wetness of the steam. It was 
necessary, therefore, to consider how far this was due to faulty 
engineering. The Turner engine was a distinctly smaller engine 
than the Adams engine, and was worked to a proportionately 
greater indicated power. If the Turner engine had been worked 
at a rather less power, the automatic valve gear would have cut 
off steam earlier in the stroke, the boiler would have been less 
forced, and almost certainly the steam consumption per H. P. 
would have been less. Looking to the fact that these small 
boilers must be somewhat forced, it is worthy of consideration 
by makers whether some superheating surface, or, at any rate, 
an efficient separator on the steam pipe, is not essential. 
The small superiority in steam consumption is the only ad- 
vantage the Adams engine gained. In coal consumption it is 
very inferior to the Turner engine. 
Discussion of the Indicator Diagrams. 
In order to compare the action of the steam in the three 
engines tried, an average diagram has been prepared for each 
in this way. Three or four good diagrams were taken for 
each engine, and a series of ordinates measured forxeach, both 
to the admission and expansion line and to the exhaust line. 
From the mean of the measured ordinates a new diagram was 
constructed, which represents more nearly than any single 
diagram the average action of the steam during a stroke. The 
clearance space is then set off, and a compression line for 
saturated steam has been drawn for one point, selected on the 
compression curve of the diagram. This curve should agree 
nearly with the actual curve, and does so except for the Adams 
engine. In that case either, as is probable, the clearance hae 
been assumed too small, or there was leakage during compression. 
Then any abscissas, such as a b, ef (fig. 2), represent the cushion 
steam reckoned as saturated steam at the pressures oa s 
From/ setoff fh, to represent the weight of steam admitted 
