Reply to Mr. Quinby on Crank Motion. 279 
nearly the same length as that of the clock. The remedy 
is easy: merely to conduct the cord of the weight to a 
different support from that which sustains the pendulum. 
Ant. X1X.—Reply to Mr. Quinby on Crank Motions 
TO PROFESSOR SILLIMAN. 
Str, 
Iv a note to an article on “ Crank Motion,” published in 
the last number of the American Journal, Mr. Quinby, the 
author of that article, says: ‘Since I wrote the above solu- 
tion, 1 have learned that the North-American Review con- 
tains an article in which it is stated that the crank motion 
occasions a loss of three fourths of the whole power em- 
ployed !! y 
* On referring to the article alluded to, I find the following 
statement relative.to the loss of power supposed to result from 
the reciprocating motion producedby the crank.” Mr. Quin- 
by then quotes the words of the Review as follows: ‘‘ There 
isin the steam engine a loss of power in changing the di- 
rection of its action from rectilinear to rotary, by the meth- 
ods in common practice, not very satisfactorily accounted 
for, considering the magnitude of the loss, which on an 
average amounts to three fourths of the whole power, as 
appears from the reports of the performance of the engines 
used at the mines in Cornwall.” 
Now, can any one pretend for one moment that there is 
any thing in this paragraph which warrants Mr. Quinby’s 
assertion, that the loss of power is supposed to result from 
the crank? ven the term is not to be found on the page 
from which he made the quotation; if, indeed, it occurs in 
the article. Itis expressly said that the loss of power ‘is 
not very satisfactorily accounted fer,” an observation which 
surely would not have been made, if the author had attri- 
buted it to the crank. The fact of the loss is stated in all 
its nakedness, and on authority to be seen directly ; and the 
cause of it was not connected with any mechanical agent 
whatever, and no such connexion can be inferred without 
violence to the whole statement. 
