AN IMPROVED SPIRIT OR LIQUID LEVEL AND INSTRUMENT FOR ASCERTAINING ANGLES OF INCLINATION OR ALTITUDES
Year: 1885

page_text: PROTIVNAL DI BUIFICATIO
I GEORGE PALMER EVELYN of the Army and Navy Club Pall Mall in the
County of Middlesex, Honorary Colonel 3rd Battalion East Surrey Regiment, do
hereby declare the nature of the said invention for "AN IMPROVED SPIRIT OR
LIQUID LEVEL AND INSTRUMENT FOR ASCERTAINING ANGLES OF INCLINATION OR
ALTITUDES," to be as follows:-
My Invention relates to an instrument fulfilling the purposes of a level,
clinometer or other instrument used for measuring vertical angles or ascertaining
the departure of a surface from the horizontal or vertical, and it has for its object
first to enable the exact angle of inclination (if any) to be at once ascertained or
read off at a glance and secondly to render the indexes of liquid levels generally
and similar instruments more sensitive and accurate.
According to the first part of my invention I construct the tube of the level in
the form of a semicircle or other arc (or I use a vessel having a circular periphery)
and provide it with a correspondingly curved scale graduated according to require-
ments with reference to which the position of the air bubble will indicate the angular
measurement to be ascertained.
For ascertaining angles of inclination or altitudes the instrument may be
provided with the necessary sights and adjuncts to enable the object whose altitude
is to be ascertained, to be sighted, and the position of the index to be read off, at
the same time.
Or the instrument may be provided with a hinged limb to carry the sights and
a graduated are about the hinge, so that the sum or the difference (as the case may
be) of the angle indicated by the level and the angle made by the two limbs would
give the angular height or altitude of the object.
In order to render the index of this instrument and of other instruments (in
which an air bubble is used as the index) more sensitive and accurate the liquid is
subjected to pressure in order to compress the air of the bubble and cause the
latter to become smaller and more spherical and consequently more definite in its
indication and less liable to error by friction and capillary attraction.

page_text: I GEORGE PALMER EVELYN of the Army and Navy Club Pall Mall in the
County of Middlesex, Honorary Colonel 3rd Battalion East Surrey Regiment do
hereby declare the nature of my invention for "AN IMPROVED SPIRIT OR LIQUID
LEVEL AND INSTRUMENT FOR ASCERTAINING ANGLES OF INCLINATION OR ALTITUDES
"
and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement :-
My Invention relates to an instrument fulfilling the purposes of a level,
clinometer or other instrument used for measuring vertical angles or ascertaining
the departure of a surface from the horizontal or vertical, and it has for its object
first to enable the exact angle of inclination to the horizon (if any) to be at once
ascertained or read off at a glance without previous adjustment of the instrument
to a level and secondly to render the indexes of liquid levels generally and similar
instruments more steady and definite.
According to the first part of my invention I construct the tube or vessel of the
level in the form of a semicircle or other arc of small radius or in the form of a
segment of a sphere and provide it with a correspondingly curved scale graduated
according to requirements, with reference to which, the air bubble will indicate by
its position the angular measurement to be ascertained.
For ascertaining angles of inclination to the horizon or altitudes the instrument
may be provided with the necessary sights and adjuncts to enable the object whose
altitude is to be ascertained, to be sighted, and the position of the index to be read
off, at the same time.
Or the instrument may be provided with a hinged limb to carry the sights and
a graduated arc about the hinge or the sights may be attached to a limb tangential
to the graduated arc and carrying a vernier, so that the sum or the difference (as
the case may be) of the angle indicated by the level and the angle indicated on the
graduated arc would give the angular height or altitude of the object.
In order to render the index of this instrument and of other instruments (in
which an air bubble is used as the index) more steady and accurate the liquid is
subjected to pressure to compress the air of the bubble and cause the latter to
become smaller and more spherical and consequently more definite in its indication
and less liable to error by friction and capillary attraction.
In the accompanying drawing I have represented a few examples of the many
various forms which my improved instrument may assume according to the purpose
for which it is intended to be used.
Figure 1 is a face view Figure 2 an edge view and figure 3 an edge view partly
in section of one form of instrument.
Figures 4 and 5 are face views of other forms adapted to different purposes.
The same letters of reference indicate the same parts in all the figures.
a is the curved glass tube or vessel and b the scale of corresponding curvature
graduated according to any required system according to the purpose for which the
instrument is to be used.

page_text: in ugure i the tube a is curved to a radius of about 2-feet and is in the form of
an arc of about 30°. It is recessed into the face of a semicircular plate c having
the scale b along the upper side of the tube and having a scale d along its curved
edge divided to correspond to the divisions of the scale b regard being had to their
difference of radius. The lower edge c' of plate c is a plane surface and a line
drawn through the centres of curvature of the plate c and tube a would be per-
pendicular thereto. e is a limb carrying hinged sights fand g such as are usually
employed in similar instruments said limb being tangential to the semicircular
edge of the plate c and capable of being brought to any point therein either by
being mounted on the end of a radial arm pivoted at the centre of curvature of
plate c or by being attached to a carrier h dovetailed and curved to fit and slide in
a dovetailed groove i in the semicircular edge of the plate c. This carrier is
provided with an index or vernier for use in reference to the scale d. The bubble
in the tube a indicates the angle at which the base c¹ may be placed and the
vernier or index on the carrier indicates the angle to wbich the sight limb e
may be adjusted in sighting the object whose altitude is to be ascertained and the
sum or difference (as the case may be) of these two indications is the angular
measurement required.
The tube a is sealed at one end and closed at the other by a plug or cork
enclosed by a screw cap as shown in figure 3ª or by any other means whereby
pressure may be applied to the liquid in order to compress the air bubble.
In the instrument shown in figure 4 the tube a is in the form of an are of rather
more than 90° whose centre is at 7 the tube being recessed into the face of a plate c
carrying a scale 6 of corresponding curvature to the tube. The sides e¹ of the
plate care respectively parallel to the sides of a quadrant described from centre
and therefore at right angles to one another. The instrument in this form is
eminently adapted for use in lieu of a plumb line and for cognate purposes.
Figure 5 shows the instrument adapted for laying drains and other purposes.
It is similar to that last described and except that it is in the form of a complete
semicircle.
When the instrument is level the bubble is at the zero point when it is vertical
the bubble marks 90°.
The vessel containing the liquid need not be permanently sealed. I prefer to
make it with an opening or neck in which is inserted a piston or plunger matle of
cork or other elastic material, or it may be of inelastic material acted on by a
spring, the pressure of which on the fluid is regulated by a cap with an internal
screw which works on a male screw outside the neck. The small quantity of air
in the vessel assumes in compression a globular form and retains sufficient buoyancy
to float like a bead of air, partly immersed at the surface of the liquid. It thus
forms an efficient index, and is kept perfectly steady by the pressure.
I do not restrict myself to the direct action of a piston on the fluid as the only
means to compress the air. In one adaptation of the instrument this object is
attained by the pressure of an adjusting screw on a diaphragm of corrugated metal
like that used to form the vacuum chamber of an aneroid. This diaphragm forms
the base of a hemispherical vessel containing the liquid. The circular edge of the
glass is cemented to a metal cylinder and the piston or spring is in the space
between the diaphragm and the base of the cylinder. The vessel is filled through
an aperture in the wall of the cylinder which is afterwards stopped by a cork or
plug. The corrugations allow for the expansion of the liquid by increase of
temperature
The liquid may be water or diluted spirits. In preparing the instrument for use
I usually entirely fill it with liquid and obtain the air required by means of a cup
shaped cavity at the end of a tapering cock or plunger. The plunger being
introduced vertically into the vessel displaces a proportionate bulk of the liquid,
which escapes by the neck. The air descends in the cavity, and on the instrument
being turned up emerges from the cavity and floats as a bubble on the liquid. The
size of the bubble is regulated by the pressure applied,

page_text: The invention provides a very perfect ship clinometer. It shows the exact
extent of angular movements such as the pitching or rolling of a ship as the bubble
has no tendency to oscillate in the tube or vessel. By means of the hemispherical
instrument not only the inclination of a surface but the direction of its dip, is at
once shewn. And the combined result of any number of vertical angular movements
such as the simultaneous pitching, rolling or lurching of a ship in a seaway is at
once ascertained by means of parallel circles or other graduations, on; or adjacent
to, the spherical surface.
It may be applied to under surfaces for instance to test the level of a ceiling on
the pitch of a rafter, and may be used in elevating and depressing guns and
howitzers, making stairs, laying pipes and drains, pitching roofs, adjusting instru-
ments and for other purposes.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is
1st In a level or instrument for ascertaining angles of inclination or altitudes,
the combination of a tube or vessel whose upper surface is curved to an arc of a
circle, or segment of a sphere, with a correspondingly curved scale in proximity to
the circular or spherical surface of the tube, for use in connection with the floating
index of the instrument, substantially as shown and described.
2nd An instrument for measuring angles of inclination or altitudes consisting of
a level formed of a curved tube or vessel and corresponding scale as herein described,
in combination with a movable limb carrying sights and working tangentially to a
graduated arc, substantially as described and shown in figures 1. 2. 3 of the
drawings, for the purpose specified.
3rd The method of compressing the indexes of liquid levels and similar instru-
ments, substantially as and for the purpose specified.