354 Quinby on the maximum effect of Machines. 
When r=o, f=o, and n=o, we have d=D x ve 
When m:n::p:7r, we have 
d=Dx vp? +f) PCHRD, 
prt’) 
water, minerals, or any other heavy body, is raised by means 
of water acting by its weight in the buckets of an overshot 
whee 
When in the last case, 7=0, and f=o, we have 
2 2 3 5 
d=D x VP meet) _p=px (fae 
This case often takes plese, a particularly in pulleys ; 
and making D=1, and r=}, in 
eee 
and when p=1, and D=1, we have 
da fy ii. 
The preceding formule will be found applicable to almost 
every case which can occur; and the intelligent engineer 
will have no difficulty in sccoingdens them to any unfore~ 
seen circumstances 
Now in the art. I have amped, we have 
rpDd—r? d? —rfd? 
The expression here given is the expression for the mo- 
mentum of r ; and is the same as that given by Dr. Grego- 
_ ry, im his 4th and 5th cos. The problem, however, which 
is here considered, is different from the one considered.b; 
Dr. G Gregory in ns 4th and 5th cos. The problem which 
Prof. Farrar here considered, is this : 
a power P and weight W, and a wheel being given, to 
the one so that Pi in descending by its own gravi- 
eneral ea atl anemone ne 
