THE EXHIBITION Of 1862. 
141 
these drawbacks, it is found from practice that the non-con- 
densing engine does nearly the whole of the work, and in 
many instances drags forward (if we may use the expression) 
the piston of the old condensing engine along with it. The 
work done by the larger engine is, therefore, nil, or little more 
than what is gained by vacuum and condensation. In the 
Woolf or compound principle, this is not the case to the same 
extent ; but it yet remains to be solved what benefit there 
is in a more expensive and more complicated construction, 
when the same advantages can be obtained by the single 
cylinder. 
That is the question for solution, and to which the advocates 
of the double cylinder reply, that in working with high-pressure 
steam, the force applied to the piston of the first cylinder is 
diffused over a much smaller area, and the action is less severe 
upon the working parts of the engine than if forced, with the 
velocity of impact, upon the surface of a greatly enlarged piston, 
as in the case of the single-cylinder condensing engine. This, 
to a certain extent, is correct, only it does not effect the 
economy but simply the strength of the working parts of the 
engine. Again, it is stated that the double - cylinder engine 
produces from the same cause a more uniform motion than the 
single-cylinder engine. But the advocates for the single-cylinder 
system affirm that these objects are all attained, first, by 
cutting off the steam at a point that will produce the same rate 
of expansion as in the compound engine, and this, although 
suddenly effected, is fully compensated by the action of the 
fly-wheel, at the greatly increased speed of the engine. 
We have been the more particular in this description, as the 
question is not yet settled amongst practical men which of the 
two systems is the best ; each side has its advocates, with 
proofs which they adduce in confirmation of their respective 
theories. Without entering further into this question, we may, 
however, state that we would prefer the single-cylinder engine, 
where the advantages are the same as those of a more compli- 
cated form ; for it appears to us that no benefit is gained in the 
shape of economy by the double or the compound engine ; on 
the contrary, we are. inclined to believe there is a loss in the 
former, owing to the difficulty of working them together as one 
engine. The same reasoning will apply to what is called the 
M f Naught principle, which consists in placing a high-pres- 
sure cylinder at half-stroke, under the main working "beam of 
the ordinary condensing engine, and exhausting the steam from 
one cylinder to the other, on the same principle as already de- 
scribed in the double, horizontal, and vertical system. 
Having described the different forms and conditions of our 
stationary engines, and the improvements that have been 
