684 
Report on the Trials of Portable 
Mr. Paxman elected to run at 134 revolutions, with a pressure 
of 150 lbs., and a brake-load of 20-horse power. Nothing 
worthy of remark occurred during the trial run, which was 
characterized by perfect smoothness of working and great regu- 
larity of speed ; the governor having perfect control of the 
engine. Mr. Paxman himself again fired, exhibiting the same 
finished skill as in his previous trial. 
Quite a crowd of experts and others interested in the compe- 
tition filled the shed towards the end of this trial, when, amidst 
some excitement, it began to be understood that the run would 
undoubtedly prove a phenomenal one. At the end of the pre- 
scribed four hours, and doing a duty of 20 horses, Mr. Paxman 
had only called for 168 lbs. of coal, while, on the coal supply 
being stopped, and none of his ashes yet used, it was evident 
that the " run down " would be a long one. Finally, the engine 
was stopped at 4 hrs. 28 min. actual, and 4 hrs. 39f min. 
mechanical time, the coal used being 168 lbs., equal to a con- 
sumption of only 1"85 lbs. of coal per horse-power per hour. 
This remarkable performance, although somewhat of a " stag- 
gerer," seemed neither to depress the spirits of other exhibitors 
of compound engines, nor diminish the hope of such experts as 
had been busily inspecting drawings, that other runs of at least 
equal merit would yet be made. So that Saturday was looked 
forward to with the highest possible interest. 
Compound Portable Engine, hy Mr. Edward Humphries 
(No. 3116). — This was the second engine tested on Friday, 
the 8th, the trial run proving a disappointment. 
The boiler is of the locomotive type, and exactly similar to that of his 
Simple engine. The cylinders are mounted over the fire-bos, and, saving the 
covers, 'are jacketed and lagged, the drainage of the jackets going direct to 
the boiler. The slipper-guides are cylindrical, forming part of the cylinder 
cover in each case, and bored out. The crank brackets are of cast-iron, 
bolted to the boiler in the usual way. The cranks are of steel, "bent," and 
placed at an angle of 180° to each other, the steam from one end of the 
small cylinder exhausting direct into the opposite end of the large cylinder, 
as in the well-known " Woolf " arrangement. The shouldering of the crank- 
shaft to its bearings is some inches from the cranks themselves. There are 
no stays between the cylinder and crank-shaft bearings, or any slide for the 
latter, as in Humphries' Simple Engine, the opposition of the cranks, it was 
explained, rendering this provision unnecessary. 
The valve gear consists of three slides, of which the first admits steam to 
the small cylinder, the second exhausts from the small cylinder and admits to 
the large cylinder, while the third exhausts from the large cylinder. Slide 
No. 1 is driven from its own fixed eccentric, but slides Nos. 2 and 3 are 
operated by an eccentric common to them both. The rate of expansion is 
fixed, and the speed of the engine is controlled by a small high-speed "Porter" 
governor, acting upon a throttle-valve. The pump, exhaust-heating apparatus, 
and the remainder of this engine generally, are all similar to the Simple engine 
which has already been described. 
