$15 : Mr. PRINCE'S Account of 
the.gla(s will bear, When a glas receiver is afed; this.igage 
may be placed within it, where it wall. meafure any, degree of 
condenfation. the receiver will bear, without-danger. to. the 
gage : or the. capacity of any receiver, may: be, meafuted -by. this 
gage, | before it is removed. from its place, by íhoiving. how 
many ftrokes of the winch will throw one atmofphere into the. 
receiver, 4 then turning the. cock, to pyevent any air .eícaps. 
ing, change the gage. fer the, button : when this-is dòne, 
the degree of c denfation may.be further meafured by the-num-. 
bet of Rrokes. | | 
MT 
wheel Ma roe e on dmm n gteat eae of de 
pitons; * to remedy this, I have fitteda condenfer, of afmal- 
ler bore than the barrel of the great pump, to the-ciftern-of 
the valve-pump, to be {crewed on occafionally ; by which-the 
.conden fation may ‘be finifhed, inílead of the great pump. Of, te 
fave the work and expence of this condenfer, the valve-pump, 
if made a little. larger, May be cafily fitted for the fame purpofe, 
by having : a | plate m made.to {crew into the bottom of the cylin- 
der, occafionally, with a valve on it, opening into the ciftern < 
a hole. matt alfo be made to be opened, . on the fame eccafion, 
neat the top of the cylinder, to let air in below the pifton, 
—— this is drawn up above it. 
"The common gage, which is pakai placed under the re- 
aiebo in this pump, is placed in the front ; that it may 
‘be:feen by the perfon who is working the pump, and-that thé 
Pah? be. left free for other ufes. 
"ana 
om dn my | pump, ie, are two SENE diameter; fo that there will be about: 
Fonty- -eight pounds added to the .refiflance in opening the valves, for every amor - 
iphexe thrown into the receiver, 
