a new-confructed Air- Pump. 5rs 
allowing the common one to. rarefy ‘theair one hundred times. - 
Nothing like this, however, is to be expected, fince we fee Mr. 
Smeaton's pump, in experiment, falls fo far fhort of the theory. 
But fuppofing my pump to rarefy the air in duplicate propor-^ 
tion of what Mr. Sweaton’s does by experiment, this would 
carry the rarefaction to one million times : and whatever it falls 
fhort of this, mutt be attributed either to the imperfection of 
the machine, or the nature of the : air, or both together : orif 
this pump fhould rarefy the air only to the fame degree with’ 
Mr: Smeaton’ s, fince by conftru&tion it ought to go fo much 
further, will it not afcertain to us, in a dire& line, that the ria- . 
| ture of the air does not admit of being further rarefied by a 
pump; and that this is the reafon why Mr. Smeaton’s pump, 
in experiment, fell fo far fhort of the theory ?- If this fhould be 
the cafe, will it not be a confirmation that the power of mecha= 
nifm is not wanting - to produce a a much greater rarefaction in 
the receiver, where no body aéts immediately upon the air to ex- 
pel it, and from. which place it can only be induced to come, 
by making room for its expanfion into fome other ? I hope, in 
a little time, to be able to inform you what the refult is by ex- 
periment, and to whet doss thig pump will hyh the re- 
eM 
ceiver. = 54 1315 3 ie 
i am, &c.. Y 
JOHN PRI NCE. 
ii ; 3 t rt $ R FE r 2 Ra F m T is AN 
EIA Since this 1 i was icated, I have feen, inthe 67 thvol. of the Phi- 
lofophical Tranfacious, an see of fome experiments ‘made by Mr. Nairne, with al 
pump confirnéted on Mr. Smeaton’ ; principle : from which 1 it appears that Mr. Smena- 
ton was deceived. with refpect to the ratefaaion in his receiver, as indicated by the’ 
pear-gage ; and that the greatelt power of the pump, when the experiment was pe 
perly made, would carry the rarefaction in the receiver only to fix Duguren e uM 
