r78i 
by means of the Pipe B running from a larger VelTel, 
CD, is a fhort Pipe of ^ of an Inch Bore, two Foot in 
length, opening into the Bottom of the Ciftern 
and whofe Oritice D is always lo Inches below the 
Bottom of A* 
' iPGEEEHF, is another Pipe of the fame Bore^ 
whofe Orihce F is like wife lo Inches below the Bot- 
tom of A, This Pipe is 119 Yards long, lying a- 
long the Ground five Foot below A, except the de- 
pending Part 0 G, and the afcending Part HF. 
When F is flopped, and {A being kept full) the 
Water runs out at D, the Quantity of VVater given 
is 19 Times more than when D is flopp’d, and the 
VVater runs out at F, 
The Air confin’d in feveral Parts of the long Pipe, 
is the chief Reafon of this Difference. 
In order to get rid of the Air, which lodging in 
the Pipe, contrads its Bore, and thereby lellens the 
Quantity of Water, which is to be deliver’d at the 
llTue, I made feveral Experiments to find whereabouts 
the Air does lodge, the more eafily to let it out one 
of which was as follows. 
I took a Glafs Pipe as AB(Fig, 2.) of about one 
Inch in Diameter, 12 Foot in length from P to P j 
only the Parts A P and P B 2Lt the other End, were 
of Lead. Then pouring in Water at A, till it came 
up to B f flopping the End G) the Air lodg’d in the 
eminent Parts the Pipe at the Places mark’d CC, 
DD, and EE: But when the Water was fuffer’d to go 
out at G, the Air came forward towards G, and took 
up the Spaces c c, dd^ and e contrading the Bore of 
the Pipe as before, but flood forwarder in the Pipe, fo 
that it generally happen’d that the Space of Air began 
upon the upper part of the Eminence of the Pipe 
KB, The Glafs Pipe may be made of feveral 
Pieces join’d to each other, and to the Leaden Pipes 
and 
