Trials of Traction-Engines at Woherliampton. 545 
box is usually situated. It contains witliin it a real smoke-box, which in this 
c;ise is a very small one, just of sufiicient size to admit of access being obtained 
to the tubes. From the top of this smoko-box a funnel rises through the 
water-tank, above which it is continued by a chimney of the ordinary con- 
struction. By tliis arrangement it is intended to absorb a certain jiortion of 
the waste heat tor heating the feed water. There is also, with the same 
object, a branch in the exhaust-pipe. This engine was declared to work at 
20-horse-power, or double its nominal, at 165 revolutions, and at 120 lbs. 
pressure. It consumed 5-95 lbs. of coal per brake horse-power per hour. 
'J'he water evaporated was 7'28 lbs. for one pound of coal. The oil used was 
Hi o/,s., equal to 2^ ozs. per real horse-power per day of 10 hours. 
The indicator diagram, of which a copy is given below, shows that 23'55- 
Fig. 9. — Indicator Diagram of Messrs. Tuxford and Son's lO-Horse- 
2wwer Locomotive, No. 2677. 
horse-power was developed. The consumption of coal was therefore 5"06 lbs. 
per gross indicated horse-power. 
If anything were wanted to confirm the engineers and judges in their view 
of the desirability of taking indicator diagrams, it would be afl'orded by the 
instance of this engine. An examination of the diagrams thus taken will show, 
that while one end of the cylinder was developing 17'91-horse-power, the other 
end was developing only 5"64. Had the maker taken diagrams before ho 
exhibited the engine, it is certain that he would liave altered his slide so as to 
have corrected this error ; and had he done so he would undoubtedly have 
obtained a far better result upon the trial. 
Aveling and Porter s Q-IIorse-jiower, Group 2. — Locomotive engines with 
indiarubber internal tyres. — The only engine in this group was Aveling and 
Porter's 6-horse-power, No. 7003, price 340?., which is precisely similar to 
Xo. 7002, with the exception that the driving-wlicels are fitted with Mr. 
William Bridges Adams's indiarubber spring inner tyres. The outer tyres of 
the wheels are 11 inches wide. Upon the interior of these tyres are riveted 
two angle-irons, with their vertical limbs inwards, leaving a space of 7 inches, 
iktween these two angle-irons is placed a layer of indiarubber an inch and 
a-half thick, within which is the inner tyre of the wheel, formed of a T bar, 
with a 4-inch web and a 6-incli table to bear on the indiarubber. There is no 
connection of any kind, beyond frictional connection, between the inner tyre 
and the indiarubber, or between the indiarubber and the outer tyre. Ko. 7003 
was tried upon the break at 15-horse-po\ver, aud consumed 4"42 lbs. coal 
