it more than I would then do, not having occafion for fuch 
work; but fince I have feen Mr. Nuis his ObjedionJ have 
been Obliged in order to anfwer him to make the follow- 
ing computation. 
■ Let the diftance as he fuppofeth be 12000 foot, and the 
Capacity of each Receptacle be about one half of a cubick 
foot : I might make the wheel with the Axis to make 
their revolution in one minute of time,and lb order all things 
that the Air under the afcending plugs might come to be 
rarefied to fuch a degree, that by its Elafticity it might not 
counterpoife more than7 foot of water :but at the fame time 
the Air in the Receptacles A A,B B,would even in it's great 
eft dilatation be able to counterpoife 1 7 foot ; fo it is plain 
that the Air will be driven from the Receptacles into the 
Pumps by a ftrength equivalent to ten foot of water ; Now 
if we compute after the method publifhM in the Tranfaft- 
ion of the month diOBoher laft,what fhould be the Velocity 
of the Air driven by fuch a preffure: we fhali find that the 
faid Velocity will be about 740 foot in a fecond ; So that 
in half a minute, during which the plug goetli up, this Air 
might pafs above 2 2 coo foot,although it were not rarifi'd at 
all ; but being rarefi'd, as we do fuppofe it to be, it might 
go a great deal further. . 
I muft now take notice that according to the Honoura- 
ble Mr. Boiles Experiments quoted by Mr. /V/^^, the Rarc- 
faftion of the Air is much lefTer than he takes it to be.- 
jFor the Water contained in the Pipe N O. is fbfar from 
caufing the Air to fill up a fpace four times bigger, that 
it will not extend it felf to a fpace once bigger than be- 
fore ; confidering therefore the Velocity of the Air and the 
fmall dilatation it doth fuffer,if any one will take the trou- 
ble to compute, he will find that if the Pumps have in 
Diameter the Diagonal of a Square Poor, and the fame 
heighth; and if the fmall Tubes of communication be 
made of % part of an Inch in Diameter, fb that being 1 2 000 
iFoQt iqng, they may contain about one cubick Foot of 
;i Air; 
