4. B. Quinby on Crank Motion. 319 
in diameter; but their pailodinwicas with respect to coal, is 
only 3, 33, 4, and 5 millions. The best engine they have 
draws only fren 91 to 11 million pounds, one foot high, sith 
each bushel of coal. which is only one-third of the perform- 
ance of the best large engine employed in pumping.” 
“One of Woolf’s double [cylinder] © pee at Wheal 
Fortune mine, in May 1816, drew only three million pounds, 
one foot high, with each bushel but Sather: at Wheal = 
oes drew Stn bade ege 
crank, and to the smaflness of the engines; and, wes 
that the writer of the article in the North American Review 
offers this very case as the basis on which he founds his asser- 
tion, that “* There is, in the steam-engine, .a loss of power in 
changing the direction of its dchon, from rectilinear to rotary, 
ba ys the methods in common practice 
With respect to the first of reed opinions, j it is 10 be re- 
marked, that however respectable the writer “of the article 
Steam Engine, Rees’? Cyclopedia, may be, as a man of: 
science, his. knowledge was inadequate to the subject on 
which he: Ww rote :—for; certainly, no individual, who is com- 
petently acquainted with the steam-engine, and with the appli- 
cation of the rotative motion by the crank, would ever con- 
clude that “ therefore, all the difference must be attributed to 
the application of the rotative motion by the crank, and to 
the smallness of the engines, since there : ot other causes to 
* It will be — by ‘nit Sere, that the wr of the article in“ 
the North Am n Review, lays aside the smallness of the en engines, a 
attributes all the “didbrence t to the single cause of changing the direction 
of the power, from rectilinear to rotary, by the methods in common prac- 
fice. 
+ In the article Steam oa rem Rees’ Cyclopedia, the author states, 
that “There is, in the Philosophical Journal, a descr a goes a of a con- 
produ 
— by Mr. Samuel Clegg, for ucing a rotative motion from a 
iprocating rw whicli not only simplifies eet machine “ much, but 
exctet the power of the common crank one-third.” 
rom this we Sern what part of t the eet loss of power in the 
ste chncengine this writer would attribute to the ae. of the rota- 
tive motion by the crank; for, since he believed tha r. Clegg” § con- 
tri vance exceeds the. power of the common crank pay He it is plain 
of 
$.% 
