280 Reply to Mr. Quinby on Crank Motion. 
Mr. Quinby uext says, ‘“ With respect to the reports on 
the performance of the engines used at the mines in Corn- 
wall, [have no knowledge, and am, therefore, not able to 
refer to the authority by which they were made out. 
‘It must, however, be concluded, that a very great blun- 
der has, in some way, been committed by those who made 
the estimate, since the reciprocating motion of the steam 
engine does not in truth (abstractly considered,) occasion 
any loss whatever of the acting power.” 
Before Mr. Quinby concluded thata very great blunder 
was made in these estimates, it would have been well for 
him to have hunted up some information on the subject. 
If be had consulted so common a book as Rees’ Cyclo- 
pedia, article Steam-Engine, he would have found the fol- 
lowing statement: “‘ By agreement of a number of respect- 
able proprietors of tin and copper mines in Cornwall, who 
resolved to have ascertained the real work their respective 
steam engines were performing, &c.——“ it was agreed that 
a counter should be attached to each engine, and all the 
engines put under the superintendence of some respectable 
and competent engineer, who should report, monthly, the 
following particulars.” Then, amongst other particulars 
enumerated, ‘“ Pounds, lifted one foot high, by a bushel of 
coals.” 
“¢ Messrs. Thomas and John Lean were appointed to the 
general superintendence. and since thattime they have pub- 
lished monthly reports, &c.”? By these reports, it appears 
that two large engines used for pumping, raise on an aver- 
age about 50,000,000 pounds one foot high, for each bush- 
el of coals consumed; and one of them raised, for one 
month, 56,000,000 pounds: again, says the same work ; 
‘“‘ Before quitting the subject of double engines, employed 
to give a rotative motion to machinery by a crank, we must 
notice a remarkable difference, shewn by Messrs. Lean’s 
reports, between the performance of the small engines, em- 
ployed in drawing the matter out of the mines, and those 
in pumping water.” 
‘*We should think the loss of power from friction, in 
drawing up buckets by a rope, would not be greater than 
the friction of the pump buckets, and of the water moving 
in the pipes; therefore, all the difference must be attributed 
io the application of the rotative motion, and to the small- 
