IMPROVEMENTS IN BAROMETERS AND OTHER PRESSURE INDICATORS
Year: 1868

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane,
in the County of Middlesex, Patent Agent, for the Invention of
"IMPROVEMENTS IN BAROMETERS AND OTHER PRESSURE INDICATORS."-A
communication from abroad by Paul Baudet, of 13, Boulevart
St. Martin, Paris.
Sealed the 22nd December 1868, and dated the 2nd July 1868.
PROVISIONAL SPECIFICATION left by the said Alexander Melville
Clark at the Office of the Commissioners of Patents, with his
Petition, on the 2nd July 1868.
I, ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County
of Middlesex, Patent Agent, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN BAROMETERS AND OTHER PRESSURE
INDICATORS," to be as follows:-
This Invention relates to improvements in what are known as aneroid
barometers, mercurial barometers, and all kinds of instruments or
apparatus generally which are used for indicating varying pressures.
Barometers, pressure guages, and such like instruments indicate
atmospheric or other variations of pressure with sufficient precision

page_text: when well constructed, by as regards foretelling the weather or the
pressure from one day to the next the information required of the
barometer, for instance, is not merely to indicate its exact height but
to show whether it is rising or falling. For this purpose an index is
ordinarily used to mark the position of the hand of the barometer, or
the case of the instrument is tapped until the hand has moved in one
direction or the other. These methods, the first of which requires
to be performed with great regularity, while the other often leaves
the observer in doubt, cannot be employed supposing several persons
wish to consult the instrument in succession. The index does not
indicate whether the pressure is stationary or on the increase or
decrease, and the object of the present Invention is to obtain this
indication by adapting to barometers and other pressure gauges an
additional part or self-acting index to show whether the pressure is
increasing or decreasing. This index shows at all times whether the
barometer has a tendency to rise or fall without touching the
instrument, and indicates the barometrical movements as easily as the
hour is shown on a clock face, it being simply necessary to deduce
certain results from the relative positions of the index and the hand of
the barometer. This additional indication will be of great service in
many instances, as in agriculture, scientific observations, and more
especially for nautical purposes.
This indicator may be arranged to operate in various ways, some
examples of which are illustrated in the accompanying Drawings.
The first arrangement is represented in Figures 1, 2, 3, and 4, and
consists in fitting at any suitable point of the index a of the barometer
or manometer a small spring or flexible blade 6 of platina, copper, or
other metal, as shown in red, one end of which spring bears against the
dial c of the barometer or pressure guage, the other end being free.
When the pressure increases or has a tendency to increase, the hand
moves in the direction of the arrow, Figure 1, the small spring b
inclining from right to left, as indicated in Figures 1 and 3. Imme-
diately the pressure has a tendency to decrease, that is, when the hand a
begins to move in the direction of the arrow, Figures 2 and 4, the spring
plate will become inclined in the opposite direction, as represented in
these Figures. Any suitable mode of attaching the spring plate or of
regulating its friction on the dial may be adopted as experience may
determine.

page_text: A modified arrangement is represented in Figures 5, 6, and 7,
Figure 5 showing a face view of a barometer provided with the improve-
ments of this Invention; Figure 6 is an under side view of the arrange-
ment of the index and hand; and Figure 7, a side view of same.
The same letters apply to these three Figures.
a, barometrical index fixed on the axis b; c, hand oscillating at d
on the index a; e, small plate provided with two pins for limiting the
oscillation of hand c on index a; f, collar mounted loosely on the
barometer spindle; g, two small spring plates fixed at one end to the
dial, and bearing at their other end on each side of the collar f.
When the index a moves in the direction of the arrow, Figures 5 and 6,
it carries with it the index c, but the collar f being loose on spindle 6
does not participate in this movement, being held by the pressure of the
springs g, g; thus the lower end of the index will be caused to abut
against the right-hand side of the notch f, forming a stop, and the hand
oscillating at d will be inclined with regard to the barometric index,
as shown in Figures 5 and 6. If the pressure continues to increase
the hand c abutting against notch f will be carried round with the
index and collar f in contact with the springs. Immediately the
pressure decreases the reverse effect is produced, the lower end of hand c
abutting against the left side of recess f', its upper end moving in
advance of the barometric index. It will be understood that the
position of the hand with regard to the barometric index may be
varied, as, for instance, the same indications may be obtained by
making the hand to follow instead of precede the barometric index in
its motion.
Figure 8 shows another arrangement of the apparatus. a, barometric
index fixed on spindle b; c, indicator mounted loose on spindle 6 of the
barometer and moving according to the variations of temperature. One
end of this index is provided with two projecting points or pins e,,/,
between which is placed the barometric index a, the other end being
terminated by a fork e', f. h, index to be moved by hand if desired
to mark the variations of position. The index a in its movement abuts
against one or other point e, f, carrying with it the index c in one or
the other direction. If, for example, the point f is in contact with
the index a, the arrow at its head will be on the side of the fork,
indicating that the oscillation is in this direction, that is to say,
the barometer is falling; the reverse effect is produced if the index a

page_text: moves towards pin e. Thus the direction of oscillation is determined
by the index approaching one or other branch e¹, f¹, the points e, f,
serving to effect the self-acting adjustment of the index by the movement
of the barometer hand. It will be readily understood that the index may
he otherwise arranged to indicate the rising or falling of the barometer or
other pressure guage.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Alexander Melville Clark in the Great Seal Patent
Office on the 1st January 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Second day of July, in the year
of our Lord One thousand eight hundred and sixty-eight, in the thirty-
second year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Alexander Melville Clark, Her special
licence that I, the said Alexander Melville Clark, my executors,
administrators, and assigns, or such others as I, the said Alexander
Melville Clark, my executors, administrators, and assigns, should
at any time agree with, and no others, from time to time and at all
times thereafter during the term therein expressed, should and lawfully
might make, use, exercise, and vend, within the United Kingdom of
Great Britain and Ireland, the Channel Islands, and Isle of Man,
an Invention for "IMPROVEMENTS IN BAROMETERS AND OTHER PRESSURE
INDICATORS," a communication to me from abroad by Paul Baudet, of
13, Boulevart St. Martin, Paris, upon the condition (amongst others)
that I, the said Alexander Melville Clark, my executors or adminis-
trators, by an instrument in writing under my, or their, or one of
their hands and seals, should particularly describe and ascertain the
nature of the said Invention, and in what manner the same was to be
performed, and cause the same to be filed in the Great Seal Patent Office
within six calendar months next and immediately after the date of the
said Letters Patent.

page_text: NOW KNOW YE, that I, the said Alexander Melville Clark, do
hereby declare the nature of the said Invention, and in what manner
the same is to be performed, to be particularly described and ascertained
in and by the following statement, reference being had to the Sheet of
Drawings hereunto annexed, and to the letters and figures marked
thereon (that is to say) :-
This Invention relates to improvements in what are known as ancroid
barometers, mercurial barometers, and all kinds of instruments or
apparatus generally which are used for indicating varying pressures.
Barometers, pressure guages, and such like instruments indicate
atmospheric or other variations of pressure with sufficient precision when
well constructed, but as regards foretelling the weather or the pressure
from one day to the next the information required of the barometer, for
instance, is not merely to indicate the exact pressure but to show whether
it is increasing or decreasing. For this purpose an index is ordinarily
used to mark the position of the hand of the barometer, or the case of the
instrument is tapped until the hand has moved in one direction or the
other. These methods, the first of which requires to be performed with
great regularity while the other often leaves the observer in doubt,
cannot be employed supposing several persons wish to consult the
instrument in succession. The index does not indicate whether the
pressure is stationary or on the increase or decrease, and the object of
the present Invention is to obtain this indication by adapting to baro-
meters and other pressure guages an additional part or self-acting
indicator to show whether the pressure is increasing or decreasing. This
indicator shows at all times whether the barometer has a tendency to
rise or fall without touching the instrument, and indicates barometrical
movements as easily as the hour is shown on a clock face, it being simply
necessary to deduce certain results from the relative positions of the
indicator and the hand of the barometer. This additional indication
will be of great service in many instances, such as in agriculture, scientific
observations, and more especially for nautical purposes. This indicator
may be arranged to operate in various ways, some examples of which are
illustrated in the accompanying Drawings.
The first arrangement is represented in Figures 1, 2, 3, and 4, and
consists in fitting at any suitable point of the index a of the barometer
or manometer a small spring or flexible blade b of platina, copper, or
other metal or material, as shown in red, one end of which spring bears

page_text: against the dial c of the pressure guage the other end being free.
When
the pressure increases or has a tendency to increase the hand moves in
the direction of the arrow, Figure 1, the small spring 6 inclining from
right to left, as indicated in Figures 1 and 3. Immediately the pressure
has a tendency to decrease, that is, when the hand a begins to move in
the direction of the arrow, Figures 2 and 4, the spring blade will become
inclined in the opposite direction, as represented in these Figures. Any
suitable mode of attaching the spring blade or of regulating its friction
on the dial may be adopted as experience may determine.
A second arrangement is illustrated in Figures 5 and 6 of the Drawings,
Figure 5 showing a front view of a portion of the dial of a barometer or
other pressure guage on which is disposed the indicator to be herein-
after described. In this Figure the indicator shows when the hand rises
and moves in the direction of the arrow from left to right. Figure 6
shows the position of the indicator when the hand falls, that is, when
moving from right to left.
In the-first described arrangement, Figures 1, 2, 3, and 4, I apply an
additional part to the hand placed at right angles thereto and made of
some flexible material, such as cane, whalebone, or horsehair, which
being placed in contact with the surface of the dial bends in one direction
or the other, and thus indicates whether the hand has a tendency to
move forwards or backwards.
In the arrangement Figures 5 and 6 I also employ a flexible indicator
as before, but placed in the same plane as the index hand, the curvature
of the indicator for marking the rise or fall being obtained by means
of a segment provided with small pins or serrations. a is the ordinary
hand, at the end of which is fixed the flexible indicator 6 composed
of horsehair, quill, whalebone, or other material. This flexible part b
further carries a disc of paper c or other material rendering its position
more preceptible. One end of the indicator b is fixed at any point
of the hand either direct or by the aid of a small spiral spring, its free
end passing between the pins or serrations d of the segment f fixed
on the dial, as seen. In this manner the flexible part b will be held
by the pins d in rear of the hand when the latter moves in either
direction. The disc c may further be of different colors on opposite
sides and made to turn in order to indicate by the color presented to view
either wet or fine weather.
Another arrangement is represented in Figures-7, 8, and 9. Figure 7

page_text: shows a face view of a barometer provided with the improvement of this
Invention Figure 8 is an under side view of the arrangement of the
indicator and hand; and Figure 9 a side view of same. The same reference
letters apply to these three Figures. a, barometrical index hand fixed on
the axis b; c, hand oscillating at d on the index a; e, small plate provided
with two pins for limiting the oscillation of hand c on index a; f, grooved
collar mounted loosely on the barometer spindle; g, two small spring
blades fixed at one end to the dial and bearing at their other end on
cach side of the collar f. When the index hand a moves in the direction
of the arrow, Figures 7 and 8, it carries with it the indicator c, but the
collar being loose on spindle does not participate in this movement,
being held by the pressure of the springs 9, 9; thus the lower end
of the indicator c will be caused to abut against the right-hand side
of the notch f' forming a stop, and the hand oscillating at d will
be inclined with regard to the barometric index, as shown in Figures
and 8. If the pressure continues to increase the indicator c abutting
against notch f will be carried round with the hand and collar f in
contact with the springs. Immediately the pressure decreases the
reverse effect is produced, the lower end of the indicator c abutting
against the left side of recess f', it upper end moving in advance of
the barometric index.
It will be understood that the position of the indicator with regard
to the barometric index may be varied, as for instance, the same indi-
cations may be obtained by making the indicator to follow instead of
precede the barometric index in its motion.
Figure 10 shows another arrangement of the apparatus. a, barometric
index fixed on spindle b; c, indicator mounted loose on spindle b
of the barometer and moving according to the variations of tem-
perature. One end of this indicator is provided with two projecting
points or pins e, f, between which is placed the barometric index a,
the other end being terminated by a fork e¹, f'; h, index to be moved
by hand as usual if desired to mark the variations of position. The
index a in its movement abuts against one or other pivot e, f, carrying
with it the indicator c in one or other direction. If, for example, the
point is in contact with the index a the arrow at its head will be
on the side f¹ of the fork, indicating that the oscillation is in this
direction, that is to say, the hand is falling; the reverse effect is pro-
duced if the index a moves towards pin e. Thus the direction of

page_text: oscillation is determined by the index approaching onc or other
branch e, f, the points e, f, serving to effect the self-acting adjust-
ment of the indicator by the movement of the barometric hand.
Figures 11, 12, and 13 of the Drawings show an arrangement more
especially applicable to barometers with open faces or dials. Figure 11
shows a front view of a barometer of this kind, and Figure 12 a
transverse section showing the arrangement of the hand and indicator,
while Figure 13 is a detached view of the indicator. The same letters
apply to these three Figures. a, barometer dial having a central
opening b; c, hand of barometer mounted on spindle d; e, indicator
turning with slight friction on spindle d; f, semicircular bridge placed
in the open part of the dial; q, spring blade fixed on the lower end
of the indicator and bearing on bridge f; h, small plate fixed to the
indicator provided with two pins i, j, against which the hand c abuts
on moving in either direction. When the hand moves in the direction
of the arrow, Figure 9, it will abut against pin i of the indicator so
as to move the latter therewith, the spring 9 bearing at same time
on bridge f. When the hand moves in the reverse direction the
indicator remains stationary until the hand comes in contact with
pin j, at which moment the indicator will be moved by the hand but
always in rear of the same.
Figure 14 shows another arrangement, in which a is the barometer
hand; b, axis of same; c, small disc mounted loosely on axis h under-
neath the hand; d, notch made in disc c; e, pin fixed in the tail end
of hand a and entering notch d; f, g, round, square, or other geometrical
figures made on disc c on either side of the hand in different colors.
The action is as follows:-The hand in moving carries with it disc c
on the pin e abutting against one side or other of the notch d, but
before this takes place the hand in its motion will have covered either
partially or entirely one or other of the dots or figures f, g, thereby
indicating the direction of motion of the hand. In Figure 14 the hand
is shown as partially covering the sign f, which indicates that the hand
is falling; when the hand remains between the two signs f, g, it is an
indication that the barometer is stationary. It will be readily under-
stood that the indicator may be otherwise arranged to indicate the
rise or fall of the barometer or other pressure guage.
I also propose to place an allegorical figure or design in colors, for
instance, a representation of Jupiter Eolus, or it may be a compass

page_text: card at the centre of the dial of a barometer, whether mercurial, aneroid,
or other kind. This design is clouded at "changeable;" blue or azure,
at "fair," "set fair," "very dry;" and on the contrary dark clouded at
"rain" or "wind," "much rain," and "; stormy."
Having described the nature of this Invention, and the manner of
performing the same, I declare that what I claim as the Invention to be
protected by the herein-before in part recited Letters Patent is,-
1st. The application to barometers and other pressure guages of an
additional self-acting indicator operated by the instrument in any
suitable manner, for the purpose of indicating at a glance if the
atmospheric or other pressure has a rising or falling tendency or is
stationary.
2ndly. I claim the several means herein-before described for effecting
this purpose, 1st, by means of the arrangement shown in Figures 1,
2, 3, and 4, consisting of a flexible part b made of any suitable, material
fixed at right angles to the hand of the barometer or other guage,
and which is deflected to the right or left by its friction on the dial
of the instrument, substantially in the manner shown and described;
2ndly, I claim the arrangement of parts illustrated in Figures 5
and 6, consisting of a flexible part 6 attached to the hand of the
barometer or other guage in the same horizontal plane, the free end
of which flexible part is held in pins or notches d for the purpose
of producing its deflection to the right or left by the motion of the hand,
said part being also provided with a colored indicator c to render the
position of part 6 more preceptible, substantially in the manner shown
and described.
3rdly. I claim the arrangement illustrated in Figures 7, 8, and 9,
in which an indicator c is fitted to oscillate on the barometer hand
in combination with a grooved collar or disc f and spring blades g, g,
for producing such oscillating motion, all in the manner described.
4thly. I claim the arrangement of parts shown in Figure 10, consisting
of an indicator c provided with points or projections e, f, and a forked
end e, f, acting in combination with the hand of the barometer, as and
for the purpose described.
5thly. I claim the arrangement shown in Figures 11, 12, and 13,
specially applicable to barometers and other guages having open faced
lials, which consists of an indicator c provided with pins i, j, and spring g

page_text: pressing on a semicircular bridge f, the whole arranged and applied sub-
stantially in the manner shown and for the purpose specified.
6thly. I claim the arrangement shown at Figure 14, consisting of a
disc c mounted loosely on the barometer spindle and provided with
colored spots or marks f, g, which being alternately covered by the
hand serve to indicate the direction of its motion, all as herein-before
described.
In witness whereof, I, the said Alexander Melville Clark, have
hereunto set my hand and seal, this Thirty-first day of Decem-
ber, in the year of our Lord One thousand eight hundred and
sixty-eight.
Witness,
JAMES DAISH,
53, Chancery Lane,
London.
A. M. CLARK. (L.S.)