322 A.B. Quinby on Crank Motion. 
science of mechanics, to conclude that ai/ the difference 
must be attributed to the application of the rotative motion 
-by the crank, and to the smallness of the engines ; nor, that 
“there is in the steam-engine a loss of power in changing the 
direction of its action from rectilinear to rotary by the me- 
thods in common practice,” since, as before observed, there 
are other causes to which this difference may be much more 
obviously and properly referred. 
But we will suppose for a moment that all the difference 
does result from the application of the rotative motion by the 
crank, and from the smallness of the engines; or, as the wri- 
ter of the article in the N. A. Review expresses it, from 
** the changing of the direction of the power from rectilinear te 
rotary by ihe methods in common practice ;’’ and let us exa- 
mine what will be the result: —then, since one of Woolf’s 
double cylinder engines at Wheal Abraham mine, in May 
18'6, in which the direction of the power was not changed 
from rectilinear to rotary by the method in common practice, 
gave a product of 56 millions of Ibs. raised one foot high 
with each bushel of coal, and another of the very same kind 
of engines, at Wheal Var mine, in the same month, in which 
the direction of the power was changed from rectilinear to 
rotary by the method in common practice, gave a product of 
only 3-millions of Ibs. raised one foot high with each bushel, 
ly 
it follows, on the principle adopted and contended for by 
the writer ofthe article in the N. A. Review, that there is in 
this case, in changing the direction of the power from rectili- 
near to rotary by the method tn common practice, a loss of 
38> (=942 hundredths,) of the whole power employed!!! 
And now it is asked, Does the writer of the article in the 
N. A. Review presume that any person possessing an unper- 
verted mind, will believe that the prodigious difference above 
exhibited is attributable to the changing of the direction of 
the power from rectilinear to rotary, by the method in com- 
mon “ora ; or, which is precisely the same thing, to the 
crank : 
But the writer of the article in question asserts, that he did 
not connect his idea or statement of a loss of power in chang- 
ing the direction of its action from rectilinear to rotary by the 
methods in common practice, with any mechanical agent what- 
ever; and that no such connexion can be inferred without 
violence to the whole statement. On the subject of this as- 
sertion I shall only put one question. Does the writer of the 
