The Trials of Oil Engines at Cambridge. 697 
Since 1890, at each Show of the Society, the petroleum 
engine has been forcing itself more prominently into notice, 
thereby proving that it had in effect passed the experimental 
stage, and was becoming an engine of commerce, for which 
there was a steadily increasing demand. In view of the large 
accession to the ranks of petroleum-engine makers, with varying 
types of engines which were being placed before the public, it 
was evident that the time had arrived when, in the interests of 
agriculturists, a competitive trial should be made of such engines. 
It was decided, therefore, to offer prizes to be awarded on the 
result of competitive trials at the Cambridge Meeting. Two 
classes were accordingly announced, one for fixed engines such 
as might be used for driving the machinery in a dairy, for 
chaff-cutting, for light grinding and for allied purposes, and 
one for portable engines capable of undertaking ordinary estate 
sawing and threshing. 
As many as seventeen engines were entered in the fixed 
class and nine in the portable class, and of these only five had 
been withdrawn from competition up to within a few days of the 
trials. Consequently, preparations were made for the trials of 
no fewer than 21 engines, and it is to be regretted that retiring 
competitors did not send in their withdrawals earlier, and thus 
save the Society unnecessary expense. 
The conditions of the competitions were drawn up specially 
with the view of avoiding what might be called a racing trial, 
the endeavour being to ascertain what engine would give the 
most economic results, not only in respect of oil consumption, 
but also as regards maintenance and facility of working, points 
which are fully dealt with in the following report. It may 
therefore be noted that the crucial full -power test was made after 
three days’ previous working of the engine, without any inter- 
mediate cleaning out or adjustment. This condition was con- 
sidered desirable, since it had been found, from previous trials, 
that freedom from fouling after prolonged running was not a 
virtue universally possessed by such engines. It is of great in- 
terest to note that none of the engines which went through 
their “ full-load ” trials revealed on subsequent examination the 
slightest trace of fouling, thus showing a most marked improve- 
ment in their more perfect combustion as compared with some 
of the earlier engines. 
In order to facilitate comparison of the oil consumption of 
the engines in competition, it was decided that all should be 
tried with the same oil, and to carry the comparison further it 
was deemed advisable to use one of the oils which had been em- 
ployed in already published trials. Of these, Russolene was 
