198 
NATURE 
| Fuly 2, 1885 
smaller cylinder was conducted to the larger one, after 
going through a sort of intermediate receiver in the 
smoke-box. The arrangement to work the engine non- 
compound consisted of a sort of slide valve controlled by 
the driver, by which means the direction of the steam 
from the boiler was so regulated that in one position the 
engine worked compound, and in the other in the ordinary 
way ; this was called the compound valve, and was placed 
on the boiler with the necessary pipes leading to it, making 
the engine look very unsightly. In both positions the waste 
steam was exhausted in the usual way up the chimney. 
Many combinations of the above arrangement have 
been tried both in this country and on the Continent. 
The earliest trials in England were made on the Eastern 
‘Counties Railway, now part of the Great Eastern system ; 
on the Continent trials have been made extensively. In 
all cases the economy of fuel was at once apparent, but 
there was something in the arrangement which stopped 
its progress ; this most probably being the general com- 
plication of the machinery, combined with a difficulty of 
management when at work. 
In 1878 Mr. F. W. Webb, the able locomotive super- 
intendent of the London and North-Western Railway, 
commenced to make experiments with an old locomotive 
converted to the compound principle; this engine had 
two cylinders of different sizes. The results of the trials 
were of such a promising nature, that he went thoroughly 
into the subject, and eventually brought out an entirely 
new arrangement with three cylinders, which he patented. 
This arrangement is a really good practical solution of 
the question of compounding locomotive engines, and 
visitors to the International Inventions Exhibition will 
there see the sort of way it has been accomplished. The 
compound locomotive, the AZarchzoness of Stafford, built 
at Crewe Works, is a really fine engine and a credit to 
the builders. 
In attacking this problem Mr. Webb had several ob- 
jects in view besides the saving of fuel by working the 
steam compound. His arrangement has enabled him to 
do away with two of the chief sources of anxiety pertain- 
ing to the management of locomotives. 
{n most non-compound locomotives designed to take 
‘heavy loads at a high speed the arrangement of coupling 
the driving and trailing wheels together by means of out- 
side connecting-rods is a necessity ; in order that all the 
available power of the engine may be exerted without 
slipping, the wheels are coupled, so that it may be trans- 
mitted by two pairs of wheels instead of one. These con- 
necting-rods are a source of danger at high speeds, and 
when they break, which they sometimes do, the prospect 
of a serious accident is by no means distant. Again, in 
all engines having inside cylinders a two-throw cranked 
axle is required; this axle has to transmit the whole 
power of the engine; it has to withstand the constant 
vibration caused by points, crossings, and roughness of 
the road, besides the heavy straining caused by the 
powerful steam-brakes now in use. The breakage of this 
axle has been the cause of many serious accidents. In 
Mr. Webb’s compound engine both of these sources of 
danger are done away with, and in place of the two-throw 
cranked axle we find a single-throw cranked axle, amply 
strong enough to be practically unbreakable, and giving a 
length of bearing otherwise impossible. The arrangement 
of the cylinders is as follows :—The engine has two out- 
side high-pressure cylinders and one inside low-pressure 
cylinder. The high-pressure cylinders are attached to the 
frames about midway between the leading and central 
wheels, and are connected to two cranks at right angles 
on the trailing wheels. The low-pressure cylinder is 
placed between the frames at the leading end, and is con- 
nected to a single-throw crank on the axle of the middle 
pair cf wheels. The valve motion is that designed by 
Mr. David Joy, which does away with all excentrics and 
rods, and considerably reducing the number of working 
parts per cylinder. This gear is singularly easy to adapt 
to the altered circumstances required in Mr. Webb’s 
arrangement, and must have considerably helped him 
when designing the engine. 
The working of the engine is as follows :—The steam 
is taken from the boiler through the regulator in the dome 
to the smoke-box, where it is divided, and taken by means 
of a pipe to each high-pressure cylinder; here it does a 
certain amount of work, and afterwards is returned in a 
parallel pipe into the smoke-box ; each pipe is taken round 
the smoke-box and then enters the valve-chest of the 
low-pressure cylinder. Thus the steam is somewhat 
heated during its progress through the pipes in the smoke- 
box, the pipes themselves serving the purpose of an inter- 
mediate receiver. When the steam has completed its work 
in the low-pressure cylinder it is finally exhausted up the 
chimney. 
The Aarchioness of Stafford belongs to the class of 
most powerful compound locomotives yet built at Crewe, 
and is of course fitted with all Mr. Webb’s latest im- 
provements ; the reversing gear is of special design, and 
only fitted to this class of engine. It is desirable in any 
compound engine to be able to vary the cut-off of the 
steam in the high-pressure cylinders without affecting the 
cut-off in the low-pressure, or the reverse ; at the same 
time it is necessary to have the reversing gear of a loco- 
motive all worked by one lever or wheel. Mr. Webb’s 
arrangement will no doubt answer the purpose fully, the 
driver being able to vary the cut-off of the steam into the 
cylinders either individually or all at the same time accord- 
ing to circumstances. 
These engines have now been at work some time, and 
are giving good results, both as regards fuel consumption 
and steadiness of running at high speeds. There are now 
thirty-four compound engines at work on the London and 
North-Western Railway, taking their turn in working 
some of the most important trains on the system, doing 
the work thoroughly well with a considerably less con- 
sumption of coal than that required by the ordinary 
locomotive. 
Following Mr. Webb in solving the question of com- 
pounding locomotives we find Mr. T. W. Worsdell, the 
locomotive superintendent of the Great Eastern Railway, 
| at work in the same direction, but evidently for a means 
of reducing the consumption of fuel, and not, as Mr. Webb 
has done, to try and make the locomotive at the same 
time less liable to break down at high speeds. : 
In Mr. Worsdell’s design we have two inside cylinders 
of different sizes, with an arrangement to turn steam direct 
from the boiler into the low-pressure valve chest either 
when the high-pressure crank happens to be on one of the 
dead centres, or to augment the power of the engine in 
starting the train. This valve, compared with the old 
compound valve of the earlier experimental compound 
engines, is extremely simple, and is so arranged that when 
the driving wheels have made a complete revolution the 
engine will automatically commence to work compound. 
This engine is well designed and is a thoroughly good 
specimen of locomotive engineering, but we think Mr. 
Webb’s engine is to be preferred, if only on the 
grounds that it does away with double-throw cranked 
axles and outside coupling rods. No doubt, as far as coal 
consumption goes, both engines will be very nearly equal, 
this being merely a question of proper proportions given 
to the cylinders and valves. Both gentlemen are to be 
congratulated on having broken through the bounds of 
locomotive practice and having succeeded in their different 
designs. 
When we think of the millions of miles run each year 
by locomotives in this country alone, and that the com- 
pound working of the steam enables us to save three or four 
pounds of coal per mile run, the enormous saving 1s at 
once apparent, leading us to the conclusion that the com- 
pound locomotive has a great future. 
