Trials of Portable Steam-Engines at Cardiff. 
59 
point, or as soon as the speed got below tlie working' revolution, 
whichever event might first happen. 
The engines had delivered to them the usual 14 lbs. of coal 
per brake horse-power ; this coal was from the Llangennech 
Colliery, the coal with which the Society's trials have been made 
for years past. 
The following is a description (in the order in which they 
ran) of the various engines that were tried upon the brake. 
It is to be feared there will be found in this description a 
great deal of repetition, as in several of the points many of the 
engines were so nearly alike that the same language might 
properly be applied to them ; but to prevent confusion, and to 
obviate the necessity of referring from the description of one 
engine to that of another, it has been thought better to -describe 
each engine as though it stood alone. 
The first engine on the list for trial was that of Messrs. Mar- 
shall, Sons, and Co. (Limited), of Gainsborough (No. 5024). 
Price 230/. 
This engine has a cylinder of S\ inches diameter, 1 foot length of stroke. 
The heating surlace is 283 "5 feet, the fire-grate is 4 "4 feet; but at the time 
of the trial fire-bricks were introduced, so as to reduce the effective area of the 
fire-grate surface to 3 feet. 
These exhibitors elected to work at 14 horse-power on the brake ; and at 
165 revolutions per minute; they also elected to work at the maximum 
pressure allowed, viz., 80 lbs. 
The construction of this engine is as follows : 
The cylinder is placed upon the fire-box, and takes its steam from an internal 
pipe, the end of which, nearest to the smoke-box, is made with a number of 
slots on the upper side to receive the steam. The cylinder is steam-jacketed, 
as also are both covers. The slide-jacket is cast with the -cylinder, and on it 
and on tlie cylinder are two lugs, to which are bolted the solid ends of two 
tubular wrought stays, which extend from the cylinder to the crank-shaft 
bearings. These bearings are made of gun-metal, carried on cast-iron blocks ; 
to bosses in which the tubular stays arc attached. The bottoms of the cast- 
iron blocks are furnished with dovetails, free to move in dovetailed grooves, 
formed in the upper part of other castings, bolted to wrought brackets riveted 
to the boiler. By this arrangement, the exhibitors suggest, that there is freedom 
for the expansion of the boiler, and that the strain is taken by the staj^-bolts 
which connect the cylinder casting to the crank-shaft bearings. In these 
stays is also carried a wrought-iron frame, to receive the outer ends of the 
guide-bars, and to support the governor-bracket. 
The frame has a bottom piece which bears upon a boss on the top of the 
boiler cleading, or rather on the top of the feed-heater, to be hereafter 
mentioned, but this bottom piece has no connection with the boiler. The 
crank-shaft is a " bent-shaft," and is made of JStenson's mild steel. On the 
one end is the fly-wheel, provided with counterbalance, and on the other 
the eccentric, driving the feed-pump. 
The four guide-bars are of cast steel. The guide-blocks are of cast iron, 
and an adjustment for wear is made by brass liners to the guide-bars. 
The steam is admitted to the cylinder by two gun-metal short slides, 
connected by a rod with an adjusting screw. These slides have, cast through 
