BW Rejoinder to Mr. Quinby on Crank Motion. 
tribute the loss to the crank, any more than to the fly 
wheel, the connecting rod, or any other, the most insignifi- 
cant part concerned in the motion. The loss was said te 
belong, not to engines of any peculiar structure, but was ex- 
tended to all the methods in ‘‘common practice ;” thus in- 
cluding engines in which the rotation is produced by the 
sun aud planet wheels, and which consequently has no 
crank about it, as well as those in which a crank is used. 
The fact was rested on Leans’ reports, in which it is stated 
that taking an average of a vast number of the engines used 
in Cornwall, those which raise their load directly by the 
working beam perform a great deal more work, from the 
consumption of a given quantity of coals, than those in 
which the force is transferred from the working beam 
through another mass of machinery, in which it keeps up a 
continuous rotary motion; the engines being alike in other re- 
spects, except indeed in size, it being declared that they were 
of the peculiar construction of Watt or Woolf. It is true thet 
in the particular cases stated the force was transferred 
through acrank, yet this being in any position merely an 
arm of a lever, and consequently only capable of modifying 
without destroying force, a fact known sometime before Mr. 
Quinby’s “demonstration of the crank problem,” namely, 
in the age of Archimedes; such general terms were used as 
indicated the loss under the conditions in which it happened, 
without fixing it to any mere instrument by which the 
change of motion was produced. 
In my answer to Mr Quinby, I disclaimed attributing the 
loss in question to any mechanical agent, and it seems that 
Mr. Quinby cannot conceive to what I did attribute it. I 
can give him no aid in his dilemma, as | proiessed in the 
beginning that 1 would not undertake to account for it. 
But Mr. Quinby has discovered, after doubting the fact of 
the loss in question, circumstances which to him satisfac- 
torily account for it. These are “first the injudicious or 
wasteful application of the coal consumed ; and secondly, the 
want of a constant and sufficient load in the buckets during 
the time the engine is in action.” It seems to me very 
clear that a wasteful application of coals would not belong 
exclusively to the rotary engines, but that the pumping en- 
gines would suffer in the same degree. That it would, at 
least in some solitary instances of the numerous ones cited, 
happen that the greatest waste of coals in the werst pamp- 
