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the water may
rise up from
the surface of
the pond through
the necks by
forcing open the
valves.
3.- Opening the
mouths of the pump,
that the water
gained as above
may discharge itself
and a supply
of fresh air
equal in bulk be
taken in in consequence.
If these three
operations took
up each the same
quantity of time,
and so that the
replenishment
went on as quick
as the discharging,
and if the
aperture made
for the discharge
were equal to the
aperture made
for the admission
of the water; viz.
the sum of the
orifices of the mouths
equal to the sum
of the orifices of
the necks at the
valves, there to keep
up a constant
stream
stream raining discharging
down itself from
the pon reservoir into
which the pump discharged
itself would
require that the sum
of the orifices at the
valves should be
three times the sum
of the orifices at the
mouths. But the
time of replenishment
that is of the rise whatever were
the width of the
necks would certainly
be much
longer than that of
the discharge, that is
of the fall.
Upon opening the
Mouths the water
will continue to run
out, (unless they are
first shut) till it
it comes to the lowest
line of the mouths:
and it can not run
lower being stopt
from running back
again in the inside
by the valves.
When once therefore
it has been raised
to this level it will will
conti never sink
any lower, but continue
at that level
of course: and to raise
it to that level will require
only two or three preparatory
flashes extra at the
beginning of the operation.
The fla match
can not well be
convey'd into the
flash-chamber
at any of the
mouths: it would
be wilted by water
dripping from
the upper part
of the mouth.
It must be introduced
either
laterally at an
aperture higher
situated in short
situated above the
greatest rise of
the water, or
perpendicularly
through the
middle of the
cover
Instead of a Neck
on a floor of cast
iron, just below
the lowest level of
the water in the
pond, opening by
valves in as many
places as possible.
The will save the
expence of pipes
and nothing more
will be necessary
than a square
hollow tower of the
same diameter as
the flash-chamber
all the way down.
like the fetching of common pump.
---page break---
The mouth of the
flash-chamber may
occupy nearly the
whole extent of one
of the sides
of the square.
For a valve
either
1. Either a op clap-
-door of iron or
wood this cased with
thick iron sliding
up and down in
a groove -
or
2. a fixt grating
of flat bars on
the outside, and behind
it in the inside
a similar
grating to slide so
that its bars shall
alternatively fill coincide
with the bars
of the outer one, or
exactly fill up the spaces
between them
Advantages of the
1st valve
1. The discharge will
be performed in half
the time
2. There will be fewer
points of contact to
afford room for leakage.
Disadvantages.
It will require a force
immensely greater to
work it:
It must be at
least double the weight)2.
---page break---
2. It will have
perhaps 12 times
as far to move.
3. The motion will
be upinwards -in a
direction opposite to
that of its gravity
The second valve
slides horizontally:
and it has no greater
space to move over
than the distance between
bar and bar
of the fixt grating:
say 3 inches.
The touching surfaces
must be
kept well greased :
and the. substance
must be thick to prevent
warping.
{Line diagrams of design}
will not signify: since
by taking an observation
first of the heat,
and afterwards of the
degree of ascension
which is the result,
the proportion between
the one and the
other will be
nevertheless ascertained.
The great object will
be to ascerta make
the expulsion of the
air with a given quantity
of fewel of a given
sort as great and as
quick as possible: and
the great point to ascertain
is when a sufficient
expulsion
has taken place
This may be done
by the help of two
instruments
1. An index rod the
bottom stuck into a
board floating in the
water in the flash
-chamber: the upper
end moving up and
down freely in a
glass tube closed at
-top cemented into
the cover.
2. A thermometer,
passing through the
cover in such a manner
as that the whole
range of expansion
shall be visible
above the cover &
visible.
N.B. Both ascension
-index and thermometer
should be in one of
the corners where they
may be at as much
out of the way of the
heat of the flask as possible,
and be supported
by rings from the
wall.
The thermometer
will not indicate a
heat nearly so great
as what the air has
acquired: but this will
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Identifier: | JB/106/012/003 "JB/" can not be assigned to a declared number type with value 106.
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106 |
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012 |
flash-pump |
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003 |
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text sheet |
2 |
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recto |
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jeremy bentham |
[[watermarks::l munn [britannia emblem]]] |
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benjamin constant |
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includes drawings |
34600 |
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