Of the Velocity of Air passing into an Exhausted receiver by Denis Papin

                                Proposition.1.
From this Principle may easily be deduced this Proposition 
that of two differing liquor’s driven by the same pressure, that 
which is <u>in specie <\u> lighter must ascend higher then that which 
is heavier, and their heigth’s will be reciprocally in the same reason as their 
specifick gravity’s are. Thus, quick silver being 13 1/2 times heavier 
then water, bear’s as much pressure when it’s spring is one foot 
<s>high, as wat  <\s> above the spout hole, as water doth when it’s 
spring is 13 1/2 foot high, and the heigth to which Mercury shall 
ascend will be 13 1/2 times lesser than the heigth to which water 
shall be driven by those equall pressures.
Proposition.2.
From the foregoing Proposition another may easily be deduced 
<u>viz<\u> that Of differing liquor’s bearing the same pressure 
those that are lighter <u>in specie <\u> must acquire a greater 
swiftness, and their differing velocity’s are to one another 
as the root’s of the specifick gravity’s of the say’d liquors.
For we have seen Prop.1. that the heigth’s to be attain’d are 
in the same reason as the specifick gravity’s; Now <u>Galileus,
Hugenius <\u>, and <s>Mr Hally <\s> others have demonstrated that the Velocity’s 
of body’s are to one another as the square root’s of the heigth’s 
to which they may ascend: and so in this occasion they are also 
as the root’s of the specifick gravity’s.
If therefore we will know what is the velocity of the Air 
being driven by any degree of pressure whatsoever, we ought 
but to find what would be the velocity of water under the 
same pressure: and then take the square root’s of the specifick 
gravity’s of these two liquor’s, because as much as the square 
root of the specifick gravity of water, will exceed the 
square root of the specifick gravity of Air, so much in 
proportion will the velocity of Air exceed the velocity of 
water. For example, when I have computed what should 
be the swiftness of a bullet shott by the pneumatick engine,
as hath been described in the Philosophical Transactions,
I should first compute what was the velocity of the Air itself