Improvements in Aneroid Barometers.
Year: 1898

page_text: Improvements in Aneroid Barometers.
I, HENRY SAMUEL SPILLER WATKIN, C.B., Colonel in Her Majesty's Army, of
The Wilderness, Woolwich, do hereby declare the nature of this invention
to be as follows:
The object of the invention is to obviate the errors which take place in aneroids
of the ordinary construction when employed at high altitudes, and to reduce the
friction of the working parts as far as possible.
To effect this I employ means by which the strain on the vacuum box and
mechanism is reduced to the normal or entirely done away with.
One way of effecting this is by connecting the bottom of the vacuum box to the
base by a screw arrangement so that the bottom of the vacuum box may be raised
and thus release the pressure.
There are other ways in which this may be done; for instance, by springs
arranged to act on both top and bottom of the vacuum box, in which case the
pressure on the latter can be released by pressing the springs towards each other.
In order to reduce the friction experienced in the working of the indicating
mechanism ordinarily employed, the rocking spindle and its attached mechanism
are dispensed with, and in lieu thereof a rocking bar is attached to a spring,
which latter is actuated by one end of a bar or rod pressing pivotally on said
spring and the other end of said bar or rod being pressed upon by a bar or lever
connected to the main spring. To the free end of the rocking bar is attached a
rack which works in a pinion on the indicator axis, a spring being connected to
said rack to ensure its correct action.
When using a spring to act on each side of the vacuum box, the ends of said
springs may be connected to the ordinary rocking shaft.
Dated this 22nd day of November 1898.
HARRIS & MILLS,
23, Southampton Buildings, London, W.C., Agents.
Improvements in Aneroid Barometers.
I, HENRY SAMUEL, SPILLER WATKIN, C.B., Colonel in Her Majesty's Army, of
The Wilderness, Woolwich, do hereby declare the nature of this invention
and in what manner the same is to be performed to be particularly described and
ascertained in and by the following statement:-
The object of the invention is to obviate the errors which take place in aneroids

page_text: of the ordinary construction when employed at high altitudes and to reduce the
friction of the working parts as far as possible.
To effect this I provide the aneroid with means by which the strain on the
vacuum box and mechanism is reduced to the normal or entirely done away with.
One way of effecting this is by connecting the bottom of the vacuum box to the
base by a screw arrangement so that the bottom of the vacuum box may be raised
and thus release the pressure.
There are other ways in which this may be done, for instance by springs
arranged to act on both top and bottom of the vacuum box, in which case the
pressure on the latter can be released by pressing the springs towards each other.
In order to reduce the friction experienced in the working of the indicating
mechanism ordinarily employed, I dispense with the rocking spindle and its
attached mechanism and in lieu thereof I employ a rocking bar or lever attached
to and carried by a spring which latter is actuated by one end of a bar or rod
pressing pivotally on said spring and the other end of said bar or rod being
pressed upon pivotally by a bar or lever connected to the main spring.
To the free end of the rocking bar or lever is attached a rack which works in
a pinion on the indicator axis, a spring being connected to said rack to ensure
its correct action.
When using a spring to act on each side of the vacuum box, the ends of said
springs may be connected to the ordinary rocking shaft.
My invention is illustrated in the accompanying drawings in which :-
Fig. 1 is a plan or front view of an aneroid barometer with the indicating
hand and face or dial removed. Fig. 2 is a cross section of such aneroid com-
plete showing one method of enabling the strain on the vacuum box to be freed
therefrom when desired. Fig. 3 is a side elevation of an aneroid barometer
provided with means similar to that of the barometer shown at Figs. 1 and 2 for
removing the strain on the vacuum box and being also constructed according
to my invention in such a manner as to reduce the friction of working of the
indicating mechanism, Fig. 4 is a side elevation of an aneroid showing a modifi-
cation in the method of relieving the vacuum box from strain, and Fig. 5 is a
detail view of the stop arrangement used in connection with the form of apparatus
shown at Figs. 1 to 3.
In all the figures like parts are indicated by similar letters of reference.
C
Referring first to Figs. 1 and 2 a is the casing of the aneroid, a¹ is a cross plate
to which the ordinary base plate 6 carrying the mechanism is fixed 2 is the face
or dial plate and a³ is the glass cap or cover, c is the vacuum box which as usual
is acted upon by a spring d and to said spring is rigidly fixed an arm or lever
the outer end of which is pin-jointed to one end of a linke the other end of which
is pin-jointed to a short lever f1 fixed rigidly to the rocking shaft f. To said
rocking shaft is fixed a longer lever which is connected by link and chain f
to the wheel g¹ on the indicator spindle g, springs being also attached to said
spindle 9. to act against the lever f, g³ is the indicating hand. The aneroid as
above described is of a usual construction, but, according to one part of my
invention I fix the vacuum box c to the base plate b in the following manner. To
the vacuum box c I fix a stud the square part of which fits within a square hole
in a sleeve ¹ attached to the base plate and passing through a hole in the
plate a beyond the square part c¹ this stud is screw threaded as shown at c² and
on this screwed portion is mounted a nut wheel h provided with a pivotted
handle by which it may be rotated. To limit the motion of the wheel in both
directions, and when turned in one direction to prevent its being screwed entirely
off the stud . ; I adopt a stop mechanism of similar character to that known
in watch-making as the "Geneva stop." this consists of a one toothed wheel j
fixed to the nut wheel and a wheel k with several teeth and a blank portion.
such wheel being pivotted in the cross plate a¹. Thus when the stud c¹. is
pulled down by rotating the nut wheel until it is stopped when the bottom of
the vacuum box will come against the base plate b, the vacuum box is expanded

page_text: into its normal position for use, but when the nut wheel is rotated as far as the
stopping apparatus will permit, in the contrary direction the strain on the vacuum
box is released.
Referring to the arrangement represented at Fig. 3, the vacuum box c, spring d
acting thereon, and the parts for enabling the strain on the vacuum box and
mechanism to be reduced to the normal or entirely done away with, are similar
to those described with respect to Figures 1 and 2 but in Fig. 3 I have repre-
sented my improved means for communicating motion from the arm or lever (1
to the axis of the indicating hand with a view to the reduction of friction. In
this case the rocking shaft and the attached mechanism ordinarily employed are
dispensed with and in lieu thereof a rocking bar or lever f2* is attached to a
spring which latter is attached to the base b. The bar or lever * is of L shape
and the shorter arm thereof has a tapered recess therein to receive one end of a bar or
rod f the other end of which is located in a tapered recess in the end of the
arm or lever . To the free end of the rocking bar or lever f2* is attached one
end of a rack which works in a pinion g' on the indicator axis g, a spring f
being connected to the other end of said rack f to ensure its correct action.
Referring to Fig. 4 it will be seen that the vacuum box e instead of being fixed
to the base is suspended between two springs * which act on both top and
bottom of the vacuum box.
These springs d* are fixed to the pillar 2 on the base and each spring has
fixed thereto an arm or lever d¹ which by a link e is connected to short arms fl
fixed to the ordinary rocking shaft f, this latter having also fixed thereon the arm
or lever which is connected to a wheel g' on the axis g of the indicating hand
by a link and chain f as usual.
In order to enable the springs * to be pressed towards each other to release the
strain on the vacuum box e and thereby put the instrument out of action I employ
two internally screw threaded blocks which are suitably guided in an upright 63
to prevent rotation; through these blocks is passed a screw having right and
left handed threads to fit the screw threads within the blocks i. Thus by apply
ing a key to the square end 22 of the screw ¹, the springs * can be made to
approach each other and thereby place the instrument out of action.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is
1. The means for enabling an aneroid barometer to be thrown out of action
when required by relieving the vacuum box from the strain of its spring or
springs substantially as herein set forth.
2. In aneroid barometers the improved means for communicating motion
from the spring arm to the axis of the indicating hand with a view to the
reduction of friction in the working parts substantially as herein set forth.
Dated this 16th day of Auœust 1800
HARRIS & MILLS,
23, Southampton Buildings, London, W.C., Agents.