o84 The Trials of Light Portable Motors at Plymouth. 
the Gippeswyck, and is mechanically well designed. The valve 
gear consists of a Trick valve driven by a single eccentric, 
forming part of a Turner Hartnell governor. There is with this 
gear an automatic variation of the stroke of the slide valve 
corresponding to variations of load on the engine. The arrange- 
ment is an excellent one, and the governor acts extremely 
promptly and well. The valve gear was not, however, very 
well set for the trial, the release being decidedly too early. 
The effect of this on the economy of the engine was, nevertheless, 
probably not very great. In fig. 1 is a sketch of the Trick 
valve. The cylinder was covered with hair felt, cased in sheet 
iron, and all the steam pipes and exposed parts were well pro- 
tected from radiation. There was an ordinary plunger feed 
pump with an adjustable valve so arranged that the feed could 
be pumped direct into the boiler, or returned through a nozzle 
into the feed tank. Round this nozzle a portion of the exhaust 
steam circulated so as to heat the feed with the waste steam. 
It was necessary during the trial to cut off the feed heater, 
otherwise the consumption of steam by the engine could not 
have been ascertained. But a special experiment was made to 
ascertain how much heat could be saved by the use of the feed 
heating arrangement. The addition of the feed heater involves 
little expense, and it is a very sensible arrangement. 
The boiler was an upright boiler with a high fire-box, from 
which thirty-six H-inch tubes led horizontally into the smoke- 
box. The boiler was somewhat small for the work done in the 
official trial run, and there was some evidence, from the wetness 
of the indicators and the large cylinder condensation, that the 
boiler might have supplied wet steam. The boiler was provided 
with a lock-up, and a lever and spring balance safety valve. 
It was very well clothed, more care being taken to prevent 
radiation than in any other engine tried. The engine and 
boiler were mounted on an iron four-wheeled truck in a very 
workmanlike and satisfactory way. 
Messrs. Adams & Co.'s engine was a vertical inverted single 
cylinder engine, with a spring loaded governor acting on a 
throttle valve. The valve gear consisted of an ordinary slide 
valve and single eccentric. The governor could not be used 
during the trial, as one of its brackets fouled the indicator gear. 
The boiler was a vertical boiler with inside furnace, having two 
cross tubes Gj inches diameter and 2 feet G inches long. There 
was a very small amount of superheating surface from the chimney 
passing up through the steam space. The heating surface for the 
size of the boiler was very small. The boiler was entirely with- 
out clothing, and no doubt the radiation loss was not incou- 
