Trials of Portable Steam- Engines at Cardiff. 71 
heater is fornied of boiler plate, and is, in truth, a water side to the whole of 
the smoke-box. 
Neiir the upper part of the heater there are diaphragms, by which the 
water is made to circulate backward and forward through four horizontal 
wrouglit-iron pipes, which extend across the smoke-box, a little above the 
tube-level. From these pipes the water passes by a check-valve into the 
boiler, through the front tube-plate. 
The bearing-wheels arc of wood, the spokes being driven into sockets in the 
naves, which are cast iron, cast upon chill pins. The hind-wheels are carried 
on a wrouglit-iron axle bolted to the front side of the fire-box. The fore- 
wheels are on a wrought axle bolted beneath a wooden bed. The perch-pin 
passes through a forging fixed on the under side of the barrel, near the smoke- 
box. There is a stay from the bottom of the perch-pin to the hind axle, and 
there are a j air of chains to limit the amount of locking. 
The barrel aud fire-box are both cleaded, and the ash-pan is provided with 
a damper, regulated by a chain. 
This engine on trial ran for 2 h. 45 m. of actual time, and 2 h. 50 m. 
mechanical time, giving a consumption of 4 '94 lbs. of coal per brake horse- 
2)ower per hour. 
The consumption of coal per gross indicated horse-power was 4 "36 lbs. per 
hour, that horse-power being 13 • 6. 
The feed-water was raised to an average temperature of 164°, the quantity 
evaporated was 1568 lbs., equal to 9 • 33 lbs. of water evaporated from 212° per 
lb. of coal. 
On the subsequent trial for regularity in ruiming, it was found that the 
governor had the engine under fair control. 
The next engine in order of trial was No. 2927, The Reading 
Iron Works Company, Limited, Price 235Z. 
This engine has a cylinder of 81 inches diameter, and length of stroke 
1 foot 2 inches, a total heating surface of 211 square feet. Total grate area of 
7 "2 square feet, of which a portion was stopped up by fire-brick, leaving an 
area of 2 • 37 square feet at the time of trial. 
The exhibitors elected to run at 17 -horse-power on the brake, at 140 revo- 
lutions, and at 80 lbs. pressure. 
In this engine the cylinder is bolted on the top of the fire-box, and 
is jacketed, as are likewise the covers ; the cylinder-jacket, however, is not 
made in the usual manner by cores in the casting, but is constructed on the 
plan pursued by this firm in their engines at the Oxford Show, a plan not 
then made public. This mode of construction consists, as already casually 
mentioned, in the insertion of a f-inch thick steel bush, which really forms 
the working barrel of the cylinder ; bands are left in the casting 21 inches from 
each end, that is to say, deep enough to contain the projection on the cover, 
the steam port, and a 1-inch bearing surface beyond the port ; and it is into 
these 25 bored bands that the turned exterior of the working cylinder is 
forcibly driven by hydraulic pressure. This process appears to make a 
thoroughly successful steam-tight joint between the cylinder and the bands. 
The cylinder jacket is in direct communication with the boiler. The steam 
to work the engine is taken separately immediately from the top of the fire- 
box, and without any internal pipe. It passes by a starting valve into the 
shde jacket, in which there is a valve formed of 2 short slides cast together by 
an attachment piece. At the back of the valve, work two cast-iron expansion 
slides ; these have on their backs saddles, in the form of half nuts, in which work 
right and left-handed double-threaded screws, formed on a gun-metal slide 
stalk. 
The crank-shaft, which is 3| in. diameter, is of iron, and is cut out of the 
