TRANSACTIONS OF SECTION G. 647 
purposes which the modern system of supplying the public wants by combination 
requires. 
3. On Compound Locomotive Engines.! By Francis W. Wess, M.Inst.C.L. 
In this paper the author describes his method of compounding the locomotive 
engine. The system differs from that hitherto adopted, particularly as regards the 
number and disposition of the cylinders. Instead of having one large and one 
small cylinder, three cylinders are used, viz. two small high-pressure cylinders, 
and one large low-pressure cylinder. The two high-pressure cylinders are attached 
to the outside frame plates immediately under the foot plate, about midway 
between the leading and middle wheels, and are connected through their piston 
rods and connecting rods to the trailing wheels. The low-pressure cylinder is 
placed directly over the leading axle, and its connecting rod lays hold of a single 
throw crank on the axle of the middle pair of wheels. By this arrangement the 
engine is practically balanced, and enabled to run steadily at high speeds, and the 
wheels being driven by separate engines, coupling rods are dispensed with ; it is 
not even necessary that one pair of wheels should be of the same diameter as the 
other. A passenger engine constructed on this principle in December 1881, has 
run more than 100,000 miles, with the heaviest and quickest trains on the London 
and North Western railway, and the commercial results, when compared with 
ordinary engines doing the same class of work, have heen very satisfactory. 
4. The Mersey Railway. 
By C. Douvanas Fox, M.Inst.C.H.—See Reports, p.'370. 
5. On the Construction and Ventilation of long Railway Tunnels. 
By T. R, Crampton. 
The author explained that by the adoption of three tunnels, they can be con- 
structed cheaper where ordinary locomotives are used, give better ventilation than 
in one, and that any two of them can be used at pleasure for the traffic, whilst pure 
air for ventilation passes through the other. 
About midway of the length of the tunnels, all of them are connected together 
by large air-passages (with no valves), so that air may pass freely from one to the 
other. About midway between the centre of the tunnels and each of their ends is 
formed a branch at right angles, either above or below the other tunnels, and from 
this branch openings are formed into each of the tunnels, each opening being pro- 
vided with doors or valves clear of the main tunnels. The branch is led to any 
conyenient point, at which a pumping engine or exhausting apparatus may be 
erected for withdrawing foul air from it. If two of the tumnels are left open to 
this branch, and the third one shut off from it by closing the doors or valves, 
vitiated air will be drawn off from the two tunnels through the branch, whilst 
fresh air will enter them, partly through their open ends, and partly at the centre, 
where it is in communication with the third tunnel, so that fresh air will be drawn 
along the third tunnel, from the bottom of its vertical shaft, down which air is 
forced, provision being made for the purpose, and will pass into the other two near 
their centre, and be drawn through the branch, as above explained ; the quantity 
of pure air being sufficient, so as to dilute the bad gases. 
By means of the doors or valves above mentioned, any of the three tunnels can 
be used as fresh air inlets, whilst the others are used as outlets for the mixed im- 
pure air and gas. 
By this means all the three tunnels will be efficiently ventilated, whilst at the 
same time the line of rails in one tunnel can be repaired, whilst the other tunnels 
are used for the passage of trains; and the tunnel in which repairs are going on 
1 Published in the Lngineer, August 3, 1883, and in Engineering, August 10, 1883. 
