Improvements in Speed Indicators.
Year: 1891

page_text: Date of Application, 11th Mar., 1891
Complete Specification Left, 11th Jan., 1892-Accepted, 13th Feb., 1892
PROVISIONAL SPECIFICATION.
Improvements in Speed Indicators.
1, JAMES MURDOCH NAPIER, of York Road, Lambeth, in the County of
Surrey, Engineer, do hereby declare the nature of this invention to be as
follows:-
This invention relates to speed indicators such as are described in the
Specifications of my former Patents No. 4125 of the year 1875, No. 6021 of
the year 1884 and No. 2822 of the year 1886 in which mercury is rotated in a
vessel or container and in accordance with the varying speed of the rotation is
caused to rise and fall in a fixed central indicating tube by its varying pressure
against an orifice in connection with the fixed central tube and it has for its object
improvements in the means for preventing the escape of the mercury out of the
rotating vessel or container along with the air through the annular space between
the hollow cylindrical boss which forms a continuation of the indicating tube down-
wards into the container, and the circumference of the hole in the container through
which it passes.
In the top portion of the rotating vessel or container I form a cylindrical recess
or fit to it a cylindrical chamber which surrounds the hollow cylindrical boss which
passés down from the horizontal support of the indicating tube into the rotating vessel
or container. Within this recess or chamber and upon the boss I fit one or more rings
of triangular section so that they incline downwards at the top from the inner to
the outer circumference while the bottom is flat leaving the edge thin.
be more than one the upper ring or rings may fit loosely upon the boss but the
lowest one is tight upon it and supports the loose rings if any. The rings may also
be formed united in one piece made fast to the boss.
If there
I
The diameter of these rings and of the recess or chamber are such that the rings
do not touch the walls in the recess or chamber but leave a passage for the return
of any mercury which may work up and also for the entrance and escape of air.
provide a bottom to the recess or chamber in which the ring or rings are enclosed
and arrange in placing the ring or rings on the hollow cylindrical boss so that they
are fixed at a convenient height not to touch the bottom of the recess or chamber
which turns with the container while the ring or rings remain stationary upon the
fixed hollow cylindrical boss which passes freely through a hole in the bottom of
the recess or chamber so that the boss will not touch the bottom of the chamber
when the instrument is working. I provide a hole placed where the bottom. meets
the circumference of the recess or chamber of sufficient size to permit the mercury
which may have passed above the bottom of the recess or chamber to flow back
into the body of the container.
When the container is rotated the centrifugal force will assist to clear the recess
or chamber of mercury through the hole above referred to. In case of the speed
of rotation of the instrument being reduced from a high to a low point the mercury
falls in the indicating tube and passes through the orifice pipe, which is fixed to
the hollow cylindrical boss, into the container and the air which is displaced by it
passes out through the annular space between the hollow cylindrical boss and the
circumference of the hole in the bottom of the recess or chamber through which it
passes along under the lowest ring on the boss then up and through the annular
space or spaces between the ring or rings and the walls of the recess or chamber
and finally out of the annular space between the hole in the upper part of the
container and the hollow cylindrical boss which passes into it. The air will also
pass out through the hole at the bottom of the recess or chamber. I provide also
that the air may enter and escape from the container when the passages, mentioned

page_text: are closed by the rising of the mercury in the container above the level of the
bottom of the recess or chamber. For this purpose I preferably bore holes
through the walls of the cylindrical recess or chamber leading from the inside of
the container at the top into the recess or chamber and the more perfectly to
prevent the passage of mercury through these while leaving sufficient freedom
for the passage of air I screw the holes and plug them with cotton wool or
the like.
CARPMAEL & Co.,
Agents.
COMPLETE SPECIFICATION.
Improvements in Speed Indicators.
I, JAMES MURDOCH NAPIER, of York Road, Lambeth, in the County of
Surrey, Engineer, 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:-
This invention relates to speed indicators such
as are described in the
Specifications of my former Patents No. 4125 of the year 1875, No. 6021 of the
year 1884 and No. 2822 of the year 1886 in which mercury is rotated in a vessel
or container and in accordance with the varying speed of the rotation is caused to
rise and fall in a fixed central indicating tube by its varying pressure against an
orifice in connection with the fixed central tube and it has for its object improve-
ments in the means for preventing the escape of the mercury out of the rotating
vessel or container along with the air through the annular space between the hollow
cylindrical boss which forms a continuation of the indicating tube downwards into
the container, and the circumference of the hole in the container through which
it passes.
In the top portion of the rotating vessel or container I form a cylindrical recess
or fit to it a cylindrical chamber which surrounds the hollow cylindrical boss
which passes down from the horizontal support of the indicating tube into the
rotating vessel or container. Within this recess or chamber and upon the boss I
fit one or more ring of triangular section so that they incline downwards at the top
from the inner to the outer circumference while the bottom is flat leaving the edge
thin. If there be more than one the upper ring or rings may fit loosely upon the
boss but the lowest one is tight upon it and supports the loose rings if any. The
rings may also be formed united in one piece made fast to the boss.
The diameter of these rings and of the recess or chamber are such that the rings
do not touch the walls in the recess or chamber but leave a passage for the return
of any mercury which may work up and also for the entrance and escape of air.
I provide a bottom to the recess or chamber in which the ring or rings are enclosed
and arrange in placing the ring or rings on the hollow cylindrical boss so that they
are fixed at a convenient height not to touch the bottom of the recess or chamber
which turns with the container while the ring or rings remain stationary upon the
fixed hollow cylindrical boss which passes freely through a hole in the bottom of
the recess or chamber so that the boss will not touch the bottom of the chamber
when the instrument is working. I provide a hole placed where the bottom meets
the circumference of the recess or chamber of sufficient size to permit the mercury
which may have passed above the bottom of the recess or chamber to low back into
the body of the container.
When the container is rotated the centrifugal force will assist to clear the recess
or chamber of mercury through the hole above referred to. In case of the speed
of rotation of the instrument being reduced from a high to a low point the mercury
falls in the indicating tube and passes through the orifice pipe, which is fixed to
the hollow cylindrical boss, into the container and the air which is displaced by it
passes out through the annular space between the hollow cylindrical boss and the

page_text: Figure is a vertical section of a portion of a speed indicator which in its
general arrangement is such as is described in my former Specifications herein-
before referred to; the figure shows fully the improvements to which my present
invention relates.
Figure 2 is an underside view showing one half of the upper portion of the
mercury vessel or container.
A is the mercury vessel or container, it is mounted on an axis which is driven
by the machine the speed of which the indicator is required to show. B is the
bracket or support which carries the indicating tube; this tube is of glass so
that the mercury or a float on the surface thereof may be visible in the tube.
In the top part of the rotating vessel or chamber there is formed at the centre
the cylindrical recess a into which is fitted the cylindrical chamber a' which
surrounds the hollow cylindrical boss which passes down from the horizontal
support B of the indicating tube into the rotating vessel or container A. Upon
the boss b in the chamber are fitted three rings c, c, c². The lower ring is
fixed in its position on the boss while c', c² may be fitted loosely and rest on
ring c. The diameter of these rings is such that they do not touch the walls of
the chamber a but leave a passage for the return of any mercury which may work
up and also for the entrance and escape of air. The chamber a is provided with
a bottom a which has a hole a through which the mercury which may have passed
above the bottom of the chamber a may flow back into the body of the container A.
When also the container is rotated the centrifugal force assists to clear the
chamber a of mercury through the hole a². The orifice pipe serves for the
passage of the mercury to and from the container A and the hollow boss bas
the speed of rotation of the container varies. The holes a are provided to allow
the air to enter and escape from the container when the other passages are
closed by the mercury.
These holes a' may be screwed and packed with cotton
wool.
Figure 3 shews a variation in the forming of the recess or chamber a-the
bottom a being in this arrangement fitted in separately.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
In a speed indicator in which rotary motion is imparted to a vessel containing
mercury, and in which the mercury is thereby caused to enter an orifice and to rise
in a fixed central indicating tube; the device herein described for preventing loss
of mercury, consisting of a partially closed cylindrical chamber upon the rotating
mercury vessel and surrounding the boss at the lower end of the indicating tube,

page_text: and a fixed or stationary ring or rings within the chamber and mounted upon the
boss such stationary ring or rings serving to baffle the air escaping from the
mercury vessel, thereby causing it to deposit particles of mercury which it may
contain.
Datod this 11th dex of January 1802
CARPMAEL & Co.,
Agents for the Applicant.