Trials of Traction-Engines at Wolverhampton. 547 
nve, it is to be presumed, simply used as steam-clicsts, and as dryers and su])er- 
heatcrs. We do not see, however, how they can act very efliciently in this 
hvtter capacity, as each tube is a cul-de-sac, and tliere is nothing, therefore, to 
cause steam which has just been delivered IVom tlie water in the D tubes to go 
into tliese u))per tubes on its way to the steam outlet except when variations 
of pressure take place. It seems to ns that, leaving out of the question the law 
of the diflusion of gases, the same steam that was first in the upper D tubes 
must remain there for an indefinite period. The water is in the lower tubes 
only. Within each of these lower tubes there is a circulating tube, which 
extends from the D tube to near the end of the horizontal tube. These cir- 
culating tubes have slits along the whole of the upper surface, and two slits at 
the sides near their ends. There is also in the D tubes a baflling-plate to 
prevent "priming," placed just above the mouth of each of the circulating 
tubes. It will be seen that there is nothing in this boiler larger than the 
9-inch cylindrical tubes, and as these are made |thsof an inch thick, the boiler 
is comjietcnt to withstand great pressure. It was, as already said, worked as 
high as 180 lbs., and no doubt was quite safe at 600 lbs. The area of fire-grate 
was 6 feet, the total heating surface in the boiler, taking only, as regards the 
two outside rows of tubes, their semi-circumference, towards the fire, was 276 
feet, of which probably 184 feet may be taken as boiling surface, and 92 feet 
ns drying or super-heating surface. 
This boiler is carried on a plain wrought-iron frame made of angle iron, and 
10 inches deep ; this is swelled out at the front end into a circular form, and 
contains within it the circular frame which carries the single steering-wheel. 
This frame is provided with friction rollers to take both the downward and 
sideway pressures. It is surrounded with a grooved pullej^ in which lies a 
wire rope, which is carried alongside the frame towards the hinder end of the 
engine, where it terminates in a pitch chain, carried on a studded imlley driven 
by a worm wheel and pinion, the pinion being on the bottom of a vertical 
spindle having a single cross handle at the top for the pru'pose of steering. At 
the hinder end the frame carries a plate-iron box. The right-hand side of this 
box forms the framing for the single horizontal cylinder. This drives a crank- 
shaft just behind the waggon-shaped fire-box. On the left hand of this shaft is 
a fly-band wheel, which, however, works between the driving-wheel and the 
side of the boiler casing, and is most inconveniently placed for piitting on a 
strap; in fact, it appears as though it could not be got on without unlacing it. 
No governor was provided to regulate the engine when acting as a prime 
mover for farm machinery. At the right-hand end the crank-shaft carries a 
pinion, which gears into a wheel running on a stud, and having a jiinion 
attached to it, which gears into a spur-wheel fixed upon the driving-axle. The 
driving-wheels are 5 feet 6 inches diameter, and 15 inches wide, and are made 
with wrought-iron tyres, having plates riveted on them anglcways. These 
wheels are both loose upon the shaft, but can be coupled to it -by pins, which 
in the case of the right-hand wheel fit into holes in the spur-wheel, and, in 
the case of the left-hand wheel, fit into holes in a hauling-puUey, which is 
keyed on to the shaft, and is of use to draw the engine out of positions of 
difficult}^ by means of a rope attached to a tree or some other fixed object, and 
wound round about this pulley. The tank is below the foot-jjlate. There is 
no means of heating the feed-water from the waste steam. The feed-pump 
is.' worked off a separate eccentric. The reversing and stopping and starting 
handles are within reach of the driver, as is also the regulating cock of the 
feed-pump. There is not any provision, except that already mentioned, for 
throwing either of the driving-wheels out of gear when making a sharp curve. 
There is not any brake to this engine. As has already been said, the steering 
power is brought to the hinder part of the engine. This is done in the case of 
Aveling and Porter's engines, but there the boiler is of such a shape that the 
