322 ,d. B. (^uinhy on Crank Motion. 



science of jnechanics, to conclude that all the difference 

 nrjust 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-eno;ine a loss of power in changing tht 

 direction of its action from rectiliiicar to rotary by the me- 

 thods in common praciice^'^ 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 to 

 rotary by the methods in eommon 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 

 1816, in which the direction of the power was not changed 

 from rectilinear to rotary by the m,ethod in common practice, 

 gave a product of 56 millions of lbs. 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 lbs. raised one foot high with each bushel, 

 it follows, on the principle adopted and contended for by 

 (he writer of the 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 in common practice, a loss of 

 II, (=94^ hundredths,) of the whole power employed ! ! ! 



And now it is asked, Does the writer of the article in tht 

 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 pov)tr from rectilinear to rotary, by the method in com- 

 mon practice ; 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 



