722 The Trials of Oil Engines at Cambridge. 
required at starting, the average time taken being 13 minutes, 
and little attention was required. The oil consumption was 
decidedly higher than that of the engines just named — namely, 
1T57 lb. per brake horse-power per hour — the speed varying 
between 253 and 256 revolutions per minute, the power 
remaining very constant. 
The other engine exhibited by this firm also ran well, but 
back explosions were noticed at intervals and necessitated an 
adjustment of the pump. The ignition tube was cleaned in this 
engine also, and at the end of the third day, on stopping the 
engine, the piston was dry and unlubricated. This engine ran 
with a rather smaller consumption of oil — namely, 1*13 lb. per 
brake horse -power per hour — probably on account of its larger 
size. The speed was constant, as was the power developed, and, 
apart from the difficulties mentioned, the engine ran with little 
attention. It was subsequently withdrawn, Messrs. Weyman 
and Hitchcock electing to rely upon the “ Trusty.” 
Messrs. Campbell's engine gave considerable trouble at start- 
ing on the third day. On the first and second days it took 
13 and 19 minutes respectively, but on the third two attempts 
with one man, seven with two men, and one with three were 
recorded before the engine finally got away, 33 minutes in all 
being occupied. The governing of the engine was not entirely 
satisfactory, a good deal of thumping and irregularity of speed 
being noticeable at times. When the vaporiser is hot enough 
the engine can be worked without the lamp, and ran so on the 
trials for short periods. The consumption was T15 lb. of oil 
per brake horse-power per hour. 
The Britannia Go's engine stopped once or twice on the first 
day from various causes, chiefly accidental. On the second and 
third days it settled down to its work and gave little or no 
trouble. The average revolutions per minute on the three days 
did not vary greatly, but there was a good deal of racing, the 
speed being by no means so steady as one would expect from 
the method of governing. The oil consumption was compara- 
tively high — namely, T49 lb. per brake horse-power per hour. 
The table opposite gives the mean results for the seven engines 
just enumerated. 
Consumption and Efficiency Trials. 
Subsequent trials were carried out with the engines just as 
they were when the three days’ run was completed, no cleaning 
or opening up of any kind being permitted. 
The arrangements were precisely the same as on the three 
days’ test, but, in addition, indicator diagrams were taken, and 
