78 
Report of the Judges on the 
On the trial for ability of governing, the results were found to be very- 
satisfactory ; not only was the engine under the most perfect control, but the 
variation in speed did not amount to 4 per cent, between the pace due to the full 
load, and that arising from working against no resistance except the trifling 
friction of the engine and brake. 
The Judges felt that this successful expansive governing arrangement was 
peculiarly one of those cases for which the Silver Medals were intended, and 
they therefore, in accordance with the regulations, sought for, and obtained, the 
approbation of the Stewards to their awarding to the Exhibitors a Medal for 
" Ilartwell's Patent Variable Expansion Governor." 
The next engine that came to trial was that of Barrows and 
Stewart, of Banbury (No. 2950). Price 230Z. 
This engine had a cylinder of 9i in. diameter, and 1 ft. 1 in. length of stroke, 
a total heating surface of 129-8 sq. ft., and a fire-grate area of 5'02 sq. ft. — the 
whole of the area being used at the time of trial. 
Fig. 9. — Indicator Diagram of Messrs. Barrotcs and Stewart's Portable 
Steam-Engine, No. 2950 (No. 4 diagram, 32 lbs. spring). 
■ The Exhibitors elected to run at 120 revolutions per minute, at 12-horse- 
power on the brake, and at 70 lbs. pressure of steam. 
The cylinder is bolted on to the top of the barrel, near the smoke-box end, 
is not steam-jacketed, except for about half its circumference, and this is done 
by the steam on its way to the slide-chest. The cylinder-casting also contains 
the slide-jacket, the starting-valve box, and the throttle-valve. There is not 
any expansion-slide. The single slide is worked by an eccentric in the ordinary 
manner ; the throttle-valve is worked by the governor. The feed-pump derives 
its motion direct from the piston-rod cross head, and is supported by flancbes 
alongside the cylinder, and under the lagging ; it is of gun-metal. 
The exhibitors claim for this construction simplicity, and a diminution of 
the number of attachments to the boiler. The governor is of the ordinary type, 
but it is rendered more sensitive by the addition of a spiral spring round about 
the spindle.* 
* The question of the sensitiveness of governors is touched upon in the con- 
cluding remarks. 
