316. Mr. PRINCE'S Account of : 
“AN EXPEANATION: OF THE: PLATES. 
PLATE ly. RO ry A view of the pump. at up, i 
not in ufe ; appearing through a. glafs. window, as fhewn by the: 
pricked. lines.. a | 
Fig. 2... A view of "e pump ien opened "i uncovered, 
for experiments; .. ç 
i Bag. g. V ansie fe&ion A one. of the. "piii Ge 
two cifterns, condenfing gage, &c. where A B; reprefents. the: 
barrel: C.D. the ciftern on which it ftands;; aa aa the. leathered: 
joint, fank into a focket, and buried in.oil: E E is the piston; the: 
rod pafi: ing througha collar of leathers, G-G, in the box. 
HI. K fhows the placeof the valve on.the top-plate K L, cover- 
ed by the crofs-piece M M, into which thepipe O O is foldered ;. 
that conveys.the air from. the, valves. to. the duct. going. under the: 
valve-pamp, aS. may. be feen; in. plate V. fig. I. @ is part of the: 
faid duct; 5 is, the. joint funk into a focket in the crofs-piece: 
bs P, which connects the cifterns and hasa duct through it lead-. 
ing to them... - Into this dud open the ducts ¢ and 7, the firft lead- 
ing to the gage in. front of the pump, the other t to the cock and: - 
receiver... 
of one thoufind times.. By an account of Mr. Cowall’s, i in the 73d voL of the Phi-- 
lofophical "'ranfa&ions, I, find.an improvement made in. Mr.. Smeaton’s pump, by: 
Mr. Haas, inftrument-maker, , ‘He has:contrived to open the valve atthe bottom of” 
the barrel independent of the {pring of the air underneath; and by this improve-. 
ment he has increafed the power of the pump to one thoufand times. . This experi-. 
ent ti$a confirmation, of muri is. to be ced from tlie "en er the valve i in: 
ples contig of aring E at the bottom of the barra to which ài ig the valve: 
is fattened’ this ring i is raifed by a. pedal, connected with two wires moving through: 
. two y collars of leathers, andis. depreffed by ą-fpiral {pring contained in a focket, thë- 
whole being fixed under-the barrel of the pump:. But he has done nothing to re-- 
meye the refiftance from the valve i in the pifton, nor the. weight ‘of the. atmofpbere: 
from off the valve on the top-plate,. 
