
TRANSACTIONS OF THE SECTIONS. 119 
patented contrivances, which, had they been successful, would not have been re- 
markable for simplicity. 
The chief inconveniences attending the use of the ordinary engine are, first, the 
loss of power arising from the obliquity of the connecting rod ; and, secondly, that 
which is the necessary consequence of bringing large masses of matter alternately 
into a state of rest and motion, many times in a minute.—A great waste of power 
must follow from the obliquity of the connecting rod, since it is a fundamental 
principle in mechanics, that ‘‘ power is lost when the force which we have, and that 
which we require, do not act in precisely the same direction.”’ The oscillating 
engine obviates, to a greater or less extent, the inconvenience arising from obliquity ; 
but it increases, to a very serious amount, the quantity of power consumed in 
stopping and moving iarge masses of matter. The seriousness of such an evil 
was perceived very clearly by the experiments witnessed in this Section, on Friday 
morning last, regarding the oscillations produced in locomotive engines, by the 
alternate motion of the piston and the parts in connection with it. ‘lhe ingenious 
contrivance, on that occasion brought before the meeting, was admirably calcu- 
lated to prevent the oscillation; but, so far from diminishing the loss of power, 
due to the bringing into alternate rest and motion the reciprocating parts of the 
machine, it adds to the evil by increasing the weight of these parts. Loss of power 
and oscillation at high velocities, are far from being the only inconveniences which 
follow from this cause.—With powerful engines, intended to move machinery, there 
is an irregularity of motion arising from it, which, though not perceptible in ordi- 
nary circumstances, becomes exceedingly injurious, where regularity is—as in many 
manufactures—of deep importance. The wear and tear, also, consequent on great 
strains in opposite directions, is very considerable. 
Rotary engines may be conveniently divided into two species: in one of them 
the steam produces, at once, a rotary motion; in the other, it produces that mo- 
tion indirectly, by means of the crank, or some such contrivance. As to any of 
those engines which produce a rotary motion directly, I cannot but feel convinced, 
that, however ingenious they may be, or however smoothly they may work, from 
the very nature of things, the most simple of them must be far more difficult to con- 
struct than the ordinary engine; and, if it is at all possible to keep them steam- 
tight, it can be effected only by a complication of parts, which renders them greatly 
inferior to reciprocating engines, whatever their defects may be. Undoubtedly many 
such rotary engines are extremely beautiful, and, externally, appear sufficiently 
simple; but they depend too much, in general, on accuracy of original construc- 
tion, and do not fulfill a condition which I believe indispensable to a good engine, 
which is, that ‘‘the more it works, within reasonable limits, the better and more 
steam-tight it will be.’”’ This condition, I may venture to assert, belongs in the 
fullest degree to the engine now brought before the Section. 
While most persons admit that the ordinary engine has considerable imperfec- 
tions, all are not agreed as to the causes whence they arise. Many, confusing the 
facts connected with the crank, fall into errors regarding it; some concluding 
that because, as a lever, it does not destroy power, its application to the steam- 
engine is attended with no loss; while others infer that because its use is accompa- 
nied by a loss of power, it therefore itself destroys power. Neither opinion is cor- 
rect : and I am even free to admit that the engine now before you contains, in prin- 
ciple, a crank—which, as we are taught by the very first principles of mechanics, 
during every part of its revolution, gives back, though modified, all the force com- 
municated to it. We, therefore, did not propose to ourselves to obviate the necessity 
of using a crank, but to change the mode of its application, since to this is due the 
loss of power arising from its use. 
None being more convinced than we of the excellent qualities of the ordinary 
engine, our whole object was to retain its good points, while we endeavoured to 
exclude its defects. Nothing can be more simple nor effective than the ordinary 
piston, cylinder, slide valve, &c.: we have retained them. It is highly advan- 
tageous to work the steam expansively: we effect this as easily, and I think I could 
show to a greater extent, than can be done by the ordinary engine, and by a cone 
trivance which is completely under our control, 
