718 The Trials of Oil Engines at Cambridge. 
exhaust valve closes after the last exploded charge has escaped. 
At the same time a spiral spring shuts the oil valve in the sprayer, 
and no oil is therefore injected. 
The ignition tube is heated by an oil flame produced in a 
very simple manner. A small jet of oil is made to strike upon 
a bent wire, which dips into an oil bath kept at constant level. 
A thin film of oil is thus drawn up and carried forward with 
the blast, and, being lighted, strikes against the ignition tube as 
an intense blue flame. The arrangement of this lamp is shown 
in fig. 16. 
Oil is supplied to the reservoir by a small pump from the 
main oil-tank which is formed in the engine-bed. 
At starting, the air-pump is worked by hand until the 
required pressure is obtained. The air is then turned on to the 
sprayer and the spray lighted. By this means the vaporiser 
is heated for about 10 minutes, the smoke being discharged 
through a special valve into the exhaust. When the vaporiser 
is hot enough the valve is closed and the oil-supply turned off 1 . 
The engine should then start without difficulty. At the trials 
great trouble was found in starting, several attempts being 
generally necessary. On the first day the sprayer was opened, 
and a piece of waste found in it. As difficulty was again 
experienced on the second and third days, and on the 2 hours’ 
full-power trial, the engine was withdrawn, and a longer ignition 
tube tried. This made a marked improvement, and indicator 
diagrams subsequently taken showed sharp and good ignition. 
This was decidedly the most complicated engine competing, 
the parts and attachments being more numerous than in any 
other — a consequence, probably, of the method of vaporising 
adopted. Each part is in itself simple and ingenious, and the 
whole is constructed in a substantial and workmanlike manner. 
Its oil consumption exceeded the average, a result to which the 
frequent stoppages must have in no small measure contributed. 
Three Days’ Run at Full Load. 
According to the conditions each engine was first subjected 
to a three days’ run, during which no opening up or cleaning 
was permitted, so as to test the endurance, liability to fouling, 
consumption, steadiness of running, and attendance required, 
over a continuous period. It was found impossible to restrict 
the number of attendants to one only in all cases. One or two 
of the engines could not have started at all if this regulation had 
been rigorously enforced. It was thought better, therefore, to 
note the number of attendants required, and take this into con- 
sideration in making the awards. 
