542 Miscellaneous Imjyhments Exhibited at Doncaster. 
wliich are of the balanced piston tj'pe, so that only one steam- 
chest and one gland are requii'ed. 
Steam is admitted through the starting valve into the space 
between the pistons of the high-pressure valve, and from thence 
into the high-pressure cylinder. After having done its work 
there, it exliausts on the outside of the high-pressure valve pistons, 
and passes at a reduced pressure into the steam-chest containing 
the low-pressure valves. The outer edges of these valves admit 
the steam into the low-pressure cylinder, whilst the exhaust 
takes place through the space between the valves and passes 
thence into the funnel. The high-pi'essure cylinder is steam- 
jacketed, whilst the jacket of the low-pressure cylinder forms 
the chimney base. Part of the waste heat from the tubes is 
used in superheating the low-pressure cylinder and steam-chest. 
The arrangement is very compact, a single crank with one 
connecting rod being used, instead of a double-throw crank 
with two connecting rods. 
Messrs. Charles Burrell & Sons, Limited, St. Nicholas Woiks, 
Thetford, Norfolk, exhibited a new type of Compound Traction 
Engine (Art. 4438), in which the cylinders, instead of being 
placed as usual one alongside the other, are placed at an angle 
one above the other. The pistons of each are connected to a 
massive steel diagonal crosshead, guided, both horizontally and 
vertically, by guide-bars. By connecting the pistons of the 
engines in this way, the extra cost of the second connecting 
rod and of a two-throw crank is avoided. Live steam from 
the boiler can at pleasure be admitted into the low-pressure 
cylinder should the engine get into a difficult place to start. 
All the motions are very conveniently arranged, and the work- 
manship throughout is of high class. 
Messrs. J. IT. McLaren, Leeds, exhibited an Engine Road 
Locomotive with patent block wheels (Art. 4139). The block 
wheels (Messrs. McLaren & Boulton"s patent) furnished the 
novelty, and may be briefly described as follows : — The wjieels 
are about 7 ft. ia diameter, 16 in. on the face. The periphery 
of the wheel is divided into 68 cells, each about 6^ in. square 
and 9 in. deep, into which hard wooden blocks are loosely fitted. 
The grain of the wood points outwards, and each block is bound 
with an iron strap, about | of an inch from the end. The blocks 
are bedded on an indiarubber, felt, or other pliable cushion, and 
are loosely attached to the wheel by a bolt let into the wooden 
block several inches, the head of which is covered by a wooden 
plug ; this bolt passes through the cushion and is secured on 
the-inner rim of the wheel by a nut. As the wheel revolves, the 
Weight is brought to bear on part of three, four, or five blocks at 
