682 Report on the Trials of Portable 
the shaft, by means of a gripping pall and lever, into the proper position for 
going ahead or astern ; an arrangement which is represented as sufficient for 
all practical purposes, while involving less complication than a link-movement 
with its pair of eccentrics, &c. 
The speed of the engine is controlled by a " Pickering" governor, placed 
horizontall}'', and acting upon a throttle-valve, but the control was not good 
during the trial. 
The feed-pump lies at an angle of 45° with the crank shaft, and is secured 
to the water-tank, which is placed nearly centrally under the boiler. A 
portion of the exhaust steam is led through a Ij-in. pipe into tlie water tank, 
and heats the feed water by surface contact. The water tank is fitted with 
a small " lifter " and hand-pump, either of which may be conveniently used 
for the purpose of filling it, although the office of the pump is chiefly to fill 
the boiler itself, or to furnish, with the aid of a short piece of hose having a 
no7.zle, a strong jet of water for washing out the mud-holes of the firebox. 
Self-movement is effected by means of a pitch-chain, similar in construction 
to that used, some years ago, in " Green's " lawn-mower, but made of thin 
Ijlates of steel, of which '26 are jjlaced side by side to form a link. It was 
stated that this chain bears easily a strain'of 7 tons, while the greatest pull 
upon it when at work is tons. The driving chain passes directly from 
a small chain pulley on the crank shaft to the main road wheel (which is 
connected with its fellow through the usual differential Liear) without inter- 
mediate motions, and is put in or out of gear by a nut on the end of the 
sliaft which controls a conical friction-clutch forming jDart of the chain 
pinion. Two idle rollers, su])portcd on a pivoted arm, are emi^loyed in such 
a way that they take up the slack of the driving chain automatically, so that 
its pulling side is always; straiglit, whether the engine is running backwards 
or forwards. The road wheels and steering gear need no special descrip- 
tion, but are both of simple design, and good proportions. It is, however, 
worthy of remark that the front wheels can be locked right under the boiler, 
and the engine turned in its own length. 
In the absence of any second, or " slow " sjjeed, Nr. Cooper provides for 
such extra calls as may occasionaUy be made on the tractive power of his 
engine by admitting builer-steam to the large cyhnder whenever required. 
The starting valve is so arranged that when its lever stands in a central 
position, steam is shut off altogether ; when pulled towards the driver, the 
small cylinder only is suj^plied; while, when pushed as far as it will go past 
the midway "stopping" point, another set of ports is opened, wdiich admit 
steam to both cylinders. 
Mr. Cooper's engine is, altogether, very well designed and 
made. It exhibits a great deal of originality of the practical 
and not of the " faddy " type. Being in no sense a " racer," it 
could not be expected to figure in the first flight with more 
economical engines, but its performance was most creditable, 
and formed a specially interesting feature of this competition, 
since it furnished an example of what may be expected from 
the general introduction of compound engines of the "com- 
mercial " type. 
Mr, Cooper elected to run at 170 revolutions, and at a pressure 
of 125 lbs. with a brake load of 18-horse-power. During the 
preliminary trial, which was made with a brake load of 17-horse- 
po\verj the engine was stopped inore tliqa once to adjust" the 
