Rejoinder to Mr. Quinby ow Crané Motion. 85 
ivg engine, would equal the least waste in the best rotary 
one; thus furnishing a case where the work was equal, if 
the difference arises from a waste of coals. But this does 
not happen in any instance. The pumping engines always 
perform much better than the rotary ones. the parts concerh- 
ed in the formation of the steam being of like structure. As 
to the load in the buckets being too light, it is a sheer 
assumption of Mr. Quinby, not warranted by the statement 
of a single fact, and subject to the obvious general objection 
that | have made to the assumption of a waste of coal, which 
is that some of the pumping engines are just as likely to be 
in the same condition, of working with an insufficient load. 
But this is not all, for presuming the saperintendents of the 
mines have a common share of judgement and eapacity of 
observation, and being in the constant habit of working their 
engines; experience alone would inevitably teach them very 
nearly the load for a maximum effect, and interested as they 
are in making every possible saving, we may be certain that 
they would take the means to have their engines worked 
with the proper loads to produce it. But there are, in Corn- 
wall even, men of high endowments, familiar with every 
thing relating to the construction or working of engines, 
striving with each other to produce the greatest effect with 
their different machines ; and is it to be supposed that this 
fact, which would be before their eyes every day, has been 
so long unperceived or neglected? Does Mr. Quinby him- 
self believe his own statement to be true? His very paper 
furnishes evidence enough of his want of confidence in it; 
because if the engines are worked as he supposes them to 
be, the loss must follow as a necessary consequence; yet he 
doubts the fact of any loss, a doubt certainly applicable to 
that, which, if it existed, must inevitably produce loss. 
Mr. Quinby’s next shift is that the consumption of coals 
is not an accurate measure of the power produced. A very 
short examination will show us the weight of this objection. 
It is very evident to every one, that in any two engines, simi- 
larly constructed in all the parts concernedin the production 
of steam, the same quantity of coals of like quality will va- 
_ porize equal quantities of water, under a like pressure. In 
- practice, the quantity of water vaporized by one bushel of 
Newcastle coals, is placed by Mr. Watt within the limits of 
from eight to twelve cubic feet, and the steam thus produced 
ts found capable of raising, with Woolf’s pumping engine, ar: 
