Report on the Trials of Implements at Oxford. 445 
Lis inspection that he might be able to have the whole of the engines and 
boilers of each Exhibitor opened and taken apart, so as to obtain accurate 
drawings and to base calculations on those drawings, then, indeed, the engi- 
neering judge should be competent to form an opinion as to whether the machine 
was one constructed according to the best known rules of engineering science, 
but time does not admit of such a process as this being pursued, and happy 
indeed it is for the judges, or rather for the stewards, that the judges are not 
driven to arrive at their awards by the mode suggested ; for were they, the 
stewards would be the recipients of endless protests from the Exhibitors, 
protests embodying also all the most recondite iDrinciples of engineering at 
present received, and, looking at some of the curious things which are constantly 
brought to trial, of new and startling principles of engineering not yet to be 
found in any of the text-books. 
The Royal Society, however, still pursues, and, if we may be allowed to 
say so, wisely pursues, the ready but by no means rough test of ascertaining 
the merits of an engine by trying what is the actual work it can perform 
for a given w^eight of fuel. As an illustration of the information conveyed 
by such trials to intending purchasers, we refer onr readers to the Table of 
Results appended to the Report on Class 1, which shows that, with equal 
weights of fuel, Messrs. Clayton and Shuttleworth's engine ran 3 hours 45 
minutes 24 seconds, while Sir. Eagle's ran only 30 minutes 30 seconds, so 
that the purchaser of Messrs. Clayton's engine would get Ts times as much 
work from the consumption of a given weight of coals as the jnirchaser of 
Mr, Eagle's would get. In the case of Mr. Eagle's engine, it is true, there 
was a general air of bad design and of equally bad workmanship about the 
machine, which was enough to make the purchaser wary, however unscientific 
he might be ; but in the case of Mr. -Nicholson's engine, which only ran 55 
minutes 24 seconds, and which therefore was not quite of one-fourtb the 
economic value to a purchaser that the engine of Messrs. Clayton and Shuttle- 
worth would be, there was nothing to shock the eye ; on the contrary, the 
parts of the engine appeared to be harmoniously proportioned, and the work- 
manship and materials to be very good. The intending purchaser might 
perhaps be struck with the fact that the boiler was without clothing, and that 
the ash-pit was without a damper, but with these exceptions, such a purchaser, 
in the absence of trials, might just as readily have bought Mr. Nicholson's 
engine as that of Messrs. Clayton and Shuttleworth, and thus might have 
found himself possessed of a machine which would require four times the 
coals required by that of Messrs. Clayton and Shuttleworth's to keep it going. 
It may, perhaps, be interesting to give some account of the method followed 
by the Society, for the purpose of ascertaining what is the economic value in. 
fuel of any engine which is offered for trial. No doubt most of the old mem- 
bers know thoroughly well what this method is ; but there are many new ones 
who may not know it, and perhaps some old members who may have forgotten 
it, and to whom therefore, an explanation of the course pursued may not be 
without interest, although such an explanation is wholly unnecessary in the 
case of those who have some years' experience in these trials. The object is to 
ascertain what amount of coal per real horse-power — not nominal horse-power 
(for these are two most different things) — each engine offered for trial will 
consume. A horse-power, as everybody now knows, was settled by Watt to be 
equivalent to about 15 tons (actually 33,000 lbs.) raised through one foot in a 
minute of time. If, therefore, an exhibitor declares his engine to be 10-horse- 
power, he ought to be able to raise 150 tons through a foot in a minute of 
time, — or, what is precisely an equivalent thing, one ton through 150 feet, or 
1 cwt. through 20 times that distance, or 3000 feet. Now, obviously, the 
most satisfactory mode of ascertaining whether any particular engine could do 
this would be to have that engine tried in the neighbourhood of some tremen- 
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