Trials of Tor table Sleam-Engincs at Cardiff. 81 
The Cornish pumping-engine used to be looked upon as the 
most econoinic.vl of all. The Monthly Report for June last 
shows that their average duty in that month was 53'o millions of 
pounds raised 1 foot high by the combustion of 1 cwt. of coal, 
and that the duty of the best engine was 7 1*7 millions of pounds. 
These sound like A'ery large figures, very much as a sum 
stated in francs appears enormous, until the proper divisor is 
applied to bring it into pounds sterling, and then the bulk 
vanishes, and one is enabled to judge of the amount in relation 
to other sums with which one is familiar. 
When this reducing test is applied to the Cornish engine 
coinage, it will be found that 71"7 millions of pounds lifted 1 
foot high for a cwt. of coals, means 3 09 lbs. of coal per horse- 
power per hour, a quantity rather over ^ lb. per horse-power 
per hour more than that which was burnt by the most econo- 
mical engine tried at Cardiff ; and it must be remembered that 
not only is this best Cornish engine working with the aid of 
condensation, giving a vacuum of probably 13 lbs. on the square 
inch, but that it has an 80-inch cylinder, and 9 feet stroke, so 
that the cooling surfaces of the cylinder, and the piston friction, 
and other frictions, are considerably less relatively to the size of 
the engine, than they can be in a portable with its 9-inch 
cylinder and 1 foot of stroke. 
Following up the Cornish engine comparison it may not be 
amiss to point out, that two of the engines tried at Cardiff gave 
duties above that of the best of the engines in the J une Cornish 
Report, viz., 79*49 millions, and 76'64: millions, as against 71*7 
millions, and that the average duty of the engines tried at Cardiff 
was 57 09 millions as against 53"3 millions the average of the 
Cornish. 
Recent improvements have brought the marine steam-engine 
down to as low a consumption as 2 lbs., or under, per Indicated 
horse-power per hour ; but here again the engines are of large 
size, have the great advantage of condensation, and that a sur- 
face condensation, and in many cases the advantage (or supposed 
advantage) of compound cylinders. 
The consumption of the most economical engine tried at this 
show, of which successful indicator diagrams were obtained, the 
engine of the Reading Ironworks Company (Limited), was as 
low as 2'377 lbs. per Indicated horse-power per hour ; a con- 
sumption which will bear favourable comparison with the best 
modern marine engines, when it is remembered that those en- 
gines condense their steam, and are of large size. 
The Judges will take the liberty of throwing out, in conclu- 
sion, one or two suggestions, and they do so with the more con- 
fidence, because they know that these Reports are really studied 
VOL, IX. — S. S. G 
