582 The Trials of Light Portable Motors at Plymouth. 
its performance with that of the steam engines would have been 
interesting. 
In the second sub-class, a gas engine was entered by Messrs. 
Crossley, but was withdrawn before the trials commenced. This 
is hardly to be regretted. The performance of gas engines is 
now well understood, and nothing new could have been learned 
from another trial. Whether a gas engine can properly be 
regarded as a portable motor is open to question, and there 
would have been difficulty in fairly deciding between the merits 
of gas and petroleum engines. The fact is they do not properly 
come into competition as portable motors. Where gas is obtain- 
able from gas mains, a petroleum engine would hardly ever be 
used, and where gas is not obtainable, only a petroleum engine 
would be used for the intermittent kind of work required of an 
agricultural engine. The petroleum engine, in fact, is rather 
a competitor with steam engines of small size than with gas 
engines. 
Steam Engines. 
General description of the Steam Enr/ines entered. — The 
engine of Messrs. Simpson, Strickland & Co. (First Prize, 30Z.) 
was a small comparatively fast-running compound engine (King- 
don's patent). The compounding is of a very simple kind and 
involves no special complication or extra working parts. The 
cylinders are tandem, and the peculiarity is that a single slide 
valve regulates the admission and exhaust for both cylinders. The 
cylinders are cast in one, without jackets, and clothed with silicate 
cotton and sheet steel. There is no stuffing box between the 
cylinders, but the piston-rod connecting the pistons is grooved ; 
and this in the makers' opinion insures sufficient steam tight- 
ness. The engine had no governor, and was regulated during 
the trial by hand, the speed being very irregular. In ordinary 
work no doubt a governor would be necessary, and its absence 
may be noted as a not unimportant defect. However, as a 
governor could apparently be added without difficulty, there ap- 
peared no reason for allowing the defect of the engine in this 
respect to override all other considerations, or to disqualify the 
engine. 
The boiler was a small vertical boiler with rather closely 
packed vertical tubes. There were 15G tubes (brass), 2 feet 3 
inches long and 1 inch outside diameter. These tubes give 
sufficient heating surface in a small boiler, and as they pass up 
through the steam space the superheating surface is not incon- 
siderable. Probably a very distinct advantage in economy was 
derived from the drying of the steam by tho upper part of the 
