[ 4H ] 
barrel, that it may be forced into the receiver. I 
am, 
S I R, 
Fornivai’s-Inn-courf, Your mott humble fervant, 
April 1 6, 1752. 
J. Smeaton. 
P. S. 1 have alfo added fome draughts, and let- 
ters of reference, in order to explain myfelf more 
fully. 
Figure I. 
Is a perfpedtive view of the principal parts of the 
pump together. 
A is the barrel. 
B the cittern, in which are included the cock, with 
feveral joints. Thefe are cover’d with water to 
keep them air-tight. A little cock to let the Water 
out of the cittern, is marked 6. 
Cc c is the triangular handle of the key of the cock : 
which, by the marks on its arms, fhews how it 
it mutt be turned, that the pump may produce 
the effedt defired. 
D H is the pipe of communication between the 
cock and the receiver. 
E is the pipe, that communicates between the cock 
and the valve, on the upper plate of the barrel. 
F is the upper plate of the pump, which contains 
the collar of leathers d , and F"the valve, which is 
covered by the piece f 
GI 
