BAROMETER
Year: 1884

page_text: I DAVID WINSTANLEY of Sun-dial Cottage, Cowgap lane Marton near Blackpool
in the County of Lancashire, journalist and inventor do hereby declare the nature
of my invention for A NEW BAROMETER to be as follows viz :-
Such an arrangement of the Philosophical toy known as the " Cartesian diver"
as will cause it to float at elevations which are definite and different, under definito
and different barometric pressures of the outer air, and also of such other
appliances and arrangements as shall make the float of the said "Cartesian diver
to be but little influenced in its floating capacity by the variations of temperature
to which it is exposed.
"
There is a certain philosophical toy to be found in most physical laboratories and
known as the "Cartesian Diver." It is described in many works on science and
amongst them in *Deschanel's Natural Philosophy by Professor Everett" (pub-
lished by Blakie and Sons of London in 1871.) In this work the description may
be found accompanied by illustrations on page 108 of Part 1. The "diver"
consists essentially of a hollow vessel open beneath and having preferably a
weight attached. This hollow vessel filled partially with water and partially
with air floats in a glass containing water and covered air-tight by an elastic
membrane. Upon the application of pressure to this elastic membrane, the
"diver" sinks to the bottom of the vessel in which it is contained, and it does so
because under the pressure more water is forced into it than it contained already
and it is accordingly rendered specifically heavier. On the other hand when the
pressure is removed the "diver" rises, the elasticity of the air within it forcing
out a portion of the water and rendering the contrivance specifically lighter. Such
an apparatus cannot however be used as a barometer, for a pressure sufficient to
make the "diver" sink at all, suffices to make it sink to the bottom of the vessel
in which it is contained, and when at the bottom a levity which suffices to make
it rise at all suffices also to make it rise completely to the top. Temperature also
affects the performance of the "diver," a "rise" causing some quantity of the
water it contains to be expelled & a "fall" causing that quantity to be increased
with the same results as when these effects are obtained by variations in the
pressure.

page_text: My Invention―now to be described-consists of two distinct devices. By the
first of these, under the influence of pressures which are definite & different
the "diver" is made to sink to depths which are definite and different too, and
by the second the effects of temperature are nullified or "compensated" so far as
the "diver" is concerned.
Both these devices used together cause the "Cartesian diver" to become a true
barometer indicating the variations in the pressure of the outer air by the varying
elevations at which it floats.
My first device consists of a weight suspended from the "diver" and so
constructed and disposed that the amount of it to which the "diver " gives support
diminishes with each increment of its descent, and to an extent greater than that
to which the weight of the "diver" is itself increased by the influx of water
caused by tlie hydrostatic pressure of the liquid column under which it is
subinerged. In the drawing hereto attached this weight-my first device-is
represented as a chain which under increased pressure deposits itself link by link
on the false bottom placed for its reception, diminishing with each link deposited
the weight which the diver holds; and this chain is again picked up link by link
as the pressure is decreased-a different point of statical equilibrium being found
for each difference of barometric pressure to which the apparatus is exposed.
A variation of this device consists in the substitution of a suspended rod in place
of the suspended chain. This necessitates the use of two liquids differing in their
specific gravity & into the denser of which the rod dips deeper and deeper, as it
descends. This variation has the advantage of greater delicacy of indication and
the disadvantage of diminishing the amount of reading space.
As to my second device viz the "compensator" of the effects of temperature.
This consists of a tube containing mercury & so disposed that the mercury shall
rise and fall under the effects of temperature. This tube is shown in the drawing
as being bent & the blackened portion indicates the quick-silver. Apart from the
opening furnished by this tube the jar in which the diver" floats is closed, & is
completely filled with water. When the temperature increases the water in the
jar expands & by increasing the height of the mercurial column increases the
pressure under which the water is confined, & if proportioned properly counter-
balances the increased tension of the air within the "diver" which results from the
elevation of its temperature and thus maintains the equilibrium of the arrange-
ment in statu quo, so far as temperature is concerned without unduly influencing
its variations under different pressures.
Of course a vacuous elastic box similar to those cimployed in aneroid birometers
(and having a spring inside by preference) may be substituted for the "diver"
with a hole beneath, for though it does not increase in weight under an increased
pressure, it does increase in specific gravity from the compression of a constant
weight into a smaller volume. Neither is it necessary that water should be the
liquid used either in the jar or in the "diver." So long as the liquid is trans-
parent enough for the "diver" to be seen, its chemical nature is of. very little
consequence, if it does not act upon the apparatus, and does not freeze or boil at
the varying temperatures and pressures to which it is exposed. Water itself-
pure and simple-is of course inadmissible where the apparatus is exposed to
temperatures which freeze it. In such circumstances dilute "spirit" or something
else which does not freeze must be employed.
In point of length, the barometer now described may vary from an inch or two
(or less) to several feet. Both ways in fact the limit is determined chiefly by the
length desired and by the difficulties of construction-not by the principles on
which the instrument is based. In the drawing the cartesian barometer is shown
in section as a column fixed in a base of suitable design and intended for the
chimney piece or table. It may however be made of course as a pendent for
the wall, or for carrying in the pocket. The figures indicating" nominal inches."
of the mercurial barometer increase in value downwards in the instrument now

page_text: described, and may be engraven on the jar itself, or on some thing thereto attached
and finally as the diameter of the jar bears no fixed proportion to its length, it
may assume a merely tube like form.
Finally what I claim as my invention is, :-firstly a " Cartesian diver" having
a weight or other equivalent device (such as a spring) attached which will lessen
the burden on the "diver" as it descends, and so proportioned as to bring it to a
statical equilibrium at different elevations under different pressures, and secondly
a compensation for the effects of temperature constructed substantially as shown
but in which mercury is not of necessity the only liquid which may be used.

page_text: "
There is a certain philosophical toy to be found in most physical laboratories,
and known as the "Cartesian Diver." It is described in many works on science,
and amongst them in "Deschanel's Natural Philosophy, by Professor Everett
(published by Blakie & Sons, of London, in 1871). In this work the description
may be found, accompanied by illustrations, on page 108 of Part I. The "Diver
consists essentially of a hollow vessel inade of material specifically heavier than
water, open beneath, and having proferably a weight attached. This hollow vessel,
filled partially with water and partially with air, floats in a glass containing water
(or some other liquid) and covered air-tight by an elastic membrane. Upon the
application of pressure to this membrane the "Diver” sinks in the vessel in which
it is contained, and it does so because under the pressure moro water is forced into
it than it contained already, and it is accordingly rendered specifically heavier.
On the other hand, when the pressure is removed the "Diver" rises, the elasticity
of the air within it forcing out a portion of the water and rendering the con-
trivance specifically lighter. Such an apparatus cannot however be used as a
barometer, for a pressure sufficient to make the Diver" sink at all suffices to
make it sink to the bottom of the vessel in which it is contained, and when at the
"bottom, a levity " which suffices to make it rise at all suffices to make it rise
completely to the top. Temperature also affects the performance of the "Diver,"
"rise" causing some quantity of the water it contains to be expelled, and a "fall"
causing that quantity to be increased, with the same results as when these effects
are obtained by variations in the pressure.
E
"
te
My Invention now to be described-consists essentially of two distinct devices.
By the first of these, under the influence of pressures which are definite and
different, the "Diver" is made to sink to depths which are definite and different
too; and by the second the effects of temperature are nullified or compen-
sated" so far as the "Diver" is concerned. Both these devices used together
cause the "Cartesian Diver" to become a true barometer, indicating the varia-
tions in the pressure of the outer air by the varying elevations at which it
floats.
My First Device consists of a weight suspended from the "Diver," and so con-
structed and disposed that the amount of it to which the "Diver" gives support

page_text: diminishes with each increment of its descent, and to an extent greater than that
to which the weight of the "Diver" is itself increased by the influx of water under
the hydrostatic pressure of the liquid column under which it is submerged. In the
drawing hereto attached, this weight-my first device-is represented as a chain
which under increased pressure deposits itself link by link upon the floor of the
vessel in which the "Diver" is contained, diminishing with each link deposited
the weight which the "Diver" holds; and this chain is again picked up link by
link as the pressure is decreased,-
-a different point of statical equilibrium being
found for each difference of barometric pressure to which the apparatus is
exposed.
A variation of this device consists in the substitution of a suspended rod in
place of the suspended chain. This necessitates the use of two liquids differing in
specific gravity, and into the denser of which the rod dips deeper and deeper as it
descends. This variation has the advantage of greater delicacy of indication, and
the disadvantage of diminishing the amount of reading space.
As to my Second Device, viz.: the compensator of the effects of temperature.
This consists of a tube containing mercury, and so disposed that the mercury shall
rise and fall under the effects of temperature. This tube is shown in the drawing
as being bent, and the blackened portion indicates the quicksilver. Apart from--
the opening furnished by this tube the jar in which the "Diver" floats is closed,
and completely filled with water, with the exception of a solitary bubble of air
retained to prevent absorption from the "Diver" under increasing temperatures.
When the temperature increases the water in the jar expands, and by increasing
the height of the mercurial column increases the pressure under which the water is
confined, and if proportioned properly counter-balances the increased tension of
the air within the "Diver," resulting from an elevation in its temperature,
and thus maintains the equilibrium of the arrangemont in statu quo so far as
temperature is concerned, without materially influencing its variations under
Hat prosenroq
DUTTIEM UN INT
"
Of course, a "Vacuous Elastic Box," similar to those employed in aneroid
barometers (and having a spring inside by preference) may be substituted for the
"Diver" with a hole beneath, for though it does not increase in weight under an
increased pressure, it does increase in specific gravity from the compression of a
constant weight into a smaller volume. Neither is it necessary that water should
Diver." So long as the liquid is
be the liquid used either in the jar or in the
transparent enough for the "Diver " to be seen, its chemical nature is of very little
consequence if it does not act upon the apparatus, and does not freeze or boil at the .
varying temperatures and pressures to which it is exposed. Water itself, pure and
simple, is of course inadmissible when the apparatus is to be exposed to tempera-
tures which freeze it. In such circumstances dilute "spirit" or something else
which does not freeze must be employed.
In point of length the apparatus may vary from a few inches (or even less) to
several feet. Both ways, in fact, the limit is determined chiefly by the length
desired, and by the difficulties of construction rather than by the principles on
which the instrument is based.
0
In the drawing the cartesian barometer is shown in section as a column fixed in
a base of more or less suitable design, and intended for the chimney-piece, the
sideboard, or the table. It may, of course however, he made as a pendant for the
wall, or for carrying in the pocket. The figures indicating "nominal inches" of
the mercurial barometer increase in value downwards in the instrument now
described, and may be upon the jar itself or on something thereto attached, and

page_text: finally, as the diameter of the jar bears no fixed proportion to its length it may
assume a merely tube-like form.
In conclusion, what I claim as my invention is
"
Firstly, a Cartesian Diver" having a weight or equivalent device (such as
a spring) attached which will lessen the burden on the "Diver" as it descends,
and so proportioned as to bring it to a statical equilibrium at different elevations
under different pressures; and,
Secondly, a compensation for the effects of temperature constructed substantially
as shown, but in which mercury is not of necessity the only liquid which may be
used.