152 
Oil-Engines in Relation to Agriculture. 
particles are so minute that they are burnt in the cylinder as easily 
as the true oil-vapour, and the difficulties inherent, whether in 
vaporisation or gasification of the oil in bulk, are avoided. Thus 
the Eteve-Priestman engine makes use of all the hydro-carbon 
supplied to it without residual waste, and without the production 
of tar ; independent testimony of the most reliable kind being at 
hand to prove that the cylinder, valve chamber, and passages of 
this engine remain perfectly clean after a period of use which may be 
measured by several millions of revolutions. Such, then, being its 
present state of development, it becomes interesting to inquire a 
little more closely into the general suitability of the oil-engine for 
use on the farm. 
A farmer’s engine should be an appliance 
1. Economical of fuel. 
2. Light in weight, relatively to power developed. 
3. Using fuel procurable everywhere, easy of transport, and 
safe to store. 
.4. Requiring little skilled attention. 
5. Safe to use in the rick-yard. 
1. Economy of Fuel. — The Eteve-Priestman engine was first 
shown at the Nottingham Meeting in 1888, where Dr. Anderson 
found that it gave one brake horse-power for a consumption of If lb. 
of petroleum per hour. A “ portable ” form of the same engine was 
shown at Windsor in 1889, which on trial gave one brake horse- 
power for 1-^ lb. of oil burnt in an hour. At the Plymouth trials 
of 1890 a Priestman engine gave a duty of one brake horse-power 
for a consumption of If lb. of oil per hour, while, still more recently, 
a similar oil-engine has given a brake horse-power for rather less 
than 1 lb. of oil consumed per hour. > 4 
The trials of 1890, which lasted a week, were very carefully made 
by Professor Unwin (Journal, Yol. I., 3rd Series, 1890, p. 596), to 
whose interest in the oil-engine, first aroused at Plymouth — where, 
together with the writer,* he acted as judge of “ Small Motors ” — 
we owe most of what we now know of oil-engines. 
Speaking generally, the price of oil may be taken as \d. per lb. , 
at which rate the cost of a brake horse-power would be also one 
halfpenny per hour. The cost of a brake horse-power delivered by 
small non- condensing engines, such as are supplied to farmers, is 
never less, and often very much more, than \d. per hour, while the 
best large condensing steam-engines in existence do not give a brake 
horse-power for less than one-third of a penny per hour. In other 
words, a saving of at least one-third in the cost of fuel may be 
expected to follow from the use of the oil-engine as against the 
farmer’s steam-engine. 
2. Lightness relatively to Power. — The oil-engine above alluded 
to as under trial by Professor Unwin for a week, at Plymouth, was 
one of 5 horse nominal power, developing 7f horse-power on the 
brake, and weighed 36 cwt., including a fly-wheel of 10 cwt. 
3. Procurability , <&c., of Fuel. — Thanks to the universal use of 
