Trials of Portable Steam-Engines at Cardiff. 
73 
eccentric 0:1 tlic crank-sluift, which cau be effected by means of a screw 
passing through a drivint;-disk fixed ou the crank-shaft, and through a slot 
in the eccentric. By this means the expansion eccentric can be so jilaced as to 
give its quickest travel to the expansion slide at the moment of cut-otf, and 
thus to make that cut-oft' sharp, and to prevent it from being lingering and 
wire-drawn. 
The feed-pump is placed vertically under the crank-shaft, and is bolted on 
to a bracket on the barrel of the boiler ; it is worked by its own eccentric, and 
is regulated by a cock in the suction. The pipe from the rising clack-box of 
the pump is jointed to a li-inch copper pipe, which circulates backwards and 
forwards in a flat chamber, bent to the curve of the inside of the smoke-box. 
There are 30 feet run of this copper pipe in the chamber. From there the 
feed-water passes through a stoi>back valve, and enters the boiler by the front 
tube-plate. The waste-steam pipe is for convenience brought through the 
barrel of the boiler, but, to prevent the injurious effects which would arise 
from passing a naked exhaust-steam pipe through an atmosphere of high- 
pressure steam, this pipe is encased in another, and between the two there is 
about an inch thickness of felt. When the waste-steam pipe reaches the 
smoke-box it divides, one branch goes upwards to give the blast, the other 
branch goes into the feed-heater previously described. The uncondensed 
lx)rtion of that steam which passes into the heater issues from the other end 
of it, and joins on to the first-mentioned portion, so as to add its volume to 
the blast of waste steam. 
Both the slide-valve rods are guided in gun-metal bushes, four inches long, 
fixed in the wrought frame which carries the outer end of the guide-bars, 
and also carries the governor. The boiler is thoroughly cleaded all over. The 
internal fire-box is without any riveted seam, being welded up into one piece. 
There is the usual closed ash-pan with damper. 
The bearing-wheels have wrought-iron spokes, cast into the bosses, and into 
the rims. These latter have each two internal feathers near to their edges, 
and thus are of that which may be called a double T section. There are 
bosses between the feathers to receive the outer ends of the spokes. The 
naves of the wheels are bored out, and have loose-bored cast-iron boxes fitted 
in, and held in by three bolts. The hinder wheels are fitted on wrought- 
iron axle arms, which are forged with large D-shaped ends, by which they 
are riveted to the side plates of the fire-box. The front wheels are also fitted 
on wrought-iron axle arms, that are fastened to the front bed. The whole of 
the fore carriage is of wrought iron, with the exception of the locking-plates, 
which are of cast iron. The perch-pin is carried in a forging attached to the 
under side of the fore end of the barrel of the boiler. The lower end of this 
pin is steadied by a stay to the front of the fire-box, and the amount of locking 
is regulated by locking-chains. 
The performance of this engine has already been incidentally alluded to when 
describing engine No. 4942. 
It may be well, however, to repeat here, that on the trial this engine ran 
for 4h. 55m. 30s. actual time; and for 4h. 51m. 36s. mechanical time, 
showing a consumption of coal of 2"881 lbs. per brake horse-power per hour. 
The consumption of coal per gross indicated horse-power was 2*377 lbs. per 
hour, that horse-power being 20-58. 
The average temperature of the feed-water was about 210°, the quantity 
evaporated was 2497 lbs., equal to 10-49 lbs. of water, at 212°, per lb. of 
coal. 
The duty done by this engine was highly satisfactory, both as regards 
economical qualities and as regards its steadiness in the trials for governing 
capabilities; great intelligence and ability had obviously been bestowed upoa 
the designing and carrying out the details of this engine. 
