IMPROVEMENTS IN SPIRIT LEVELS
Year: 1885

page_text: I, JOHN THROPP of 22 Frankfort Street, Birmingham in the County of Warwick,
Manufacturer, do hereby declare the nature of said invention for "IMPROVEMENTS
IN SPIRIT LEVELS," to be as follows:-
My invention relates to levels commonly called spirit levels for determining
planes and levels.
Spirit levels as ordinarily constructed are made usually of box wood, but are
sometimes inade in malleable iron with closed bottoms. The spirit tube which
determines the plane is introduced into the level from the top by forming a recess
or mortice wherein the spirit tube is secured by cement or other means.
The top
plate covers the aperture thus formed.
or semi
My invention consists in making spirit levels hollow or somewhat
circular in cross section, that is, the level is nearly closed at top and perfectly open
at bottom, and instead of introducing the spirit tube from the front, as is common
with gauges of the ordinary construction, I introduce the said tube through the
open bottom.
The shell which is preferably produced by casting in brass or other metals or alloys,
is divided off about its middle by two walls or partitions, so as to make the middle
into a box form wherein the spirit tube is enclosed; and situated a little below the
bottom edge of the body of the gauge, two bearing seats are formed, upon which
the enclosing plate carrying the spirit tube rests.
The plate enclosing the box aperture, lies a little below the level or plane of the
gauge bottom and is affixed in position by screws.
The gauge has a longitudinal slit with a cross bar in its middle through which
the spirit tube is seen.
The ends of the gauge are rounded off, while the part or middle surrounding the
hole through which the level is seen is made flat, and curved off, so as to present
a neat and compact effect.
Should the spirit tube require to be replaced or removed, this is very simply
done by removing the bottom enclosing plate.
In consequence of the bottom of the gauge being practically open, a thin edge is
left; following the boundary of the gauge, and of the thickness of its walls; thus
[Price Sdl

page_text: the gauge is supported upon the boundary edging which is of about an eighth or
a sixteenth of an inch broad leaving the other part hollow.
The great advantage in having a hollow under body, is, that any inequalities
coming under can be readily removed, on a slight shifting motion being imparted
thereto.
The gauge so constructed, is both simple in its construction, combined with
lightness, cheapness and efficient working.
I, JOHN THROPP of 22 Frankfort Street Birmingham in the County of Warwick,
Manufacturer, do hereby declare the nature of said invention for "IMPROVEMENTS
IN SPIRIT LEVELS," 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 levels commonly called spirit levels for determining
planes and levels.
Spirit levels as ordinarily constructed are made usually of box-wood, but are
sometimes made in malleable iron with closed bottoms. The spirit tube which
determines the plane is introduced into the level from the top by forming a recess
or mortice wherein the spirit tube is secured by cement or other means.
The top
plate covers the aperture thus formed.
or semi-
My invention consists in making spirit levels hollow or somewhat
circular in cross section; that is, the level is nearly closed at top and nearly open
at bottom, and instead of introducing the spirit tube from the front, as is common
with gauges of the ordinary construction, I introduce the said tube through the
open bottom.
The shell which is preferably produced by casting in iron, brass or other metals:
or alloys, is divided off abouts its middle by two walls or partitions, so as to make
the middle into a box form wherein the spirit tube is enclosed; and situated a
little below the bottom edge of the body of the gauge, two bearing seats are formed
upon which the enclosing plate carrying the spirit tube, rests.
The plate enclosing the box aperture, lies a little below the level or plane of the
gauge bottom, and is affixed in position by screws.
The gauge has a longitudinal slit with a cross bar in its middle through which
the spirit tube is seen.

page_text: The ends of the gauge are rounded off, while the part or middle surrounding the
hole through which the level is seen, is made flat and curved off, so as to present
a neat and compact effect.
Should the spirit tube require to be replaced or removed, this is very simply
done by removing the bottom enclosing plate.
In consequence of the bottom of the gauge. being practically open, a thin edge
is left, following the boundary of the gauge, and of the thickness of its walls; thus
the gauge is supported upon the boundary edging which is of about an eighth or a
sixteenth of an inch broad, leaving the other part hollow.
The great advantage in having a hollow under body, is, that any inequalities
coming under can be readily removed, on a slight shifting motion being imparted
thereto.
The gauge so constructed, is both simple in its construction, combined with
lightness, cheapness and efficient working.
I will now proceed to describe with reference to the accompanying Drawing the
manner in which the same is to be performed.
Figure 1 is a side elevation, figure 2 a plan, figure 3 a longitudinal vertical
section and figure 4 an underside view of a spirit level provided with an open
bottom and constructed according to my invention. Figure 5 is also an underside
view of the level with the enclosing plate of the box portion removed. Figure 6
is an end elevation of figure 1, and figure 7 is a transverse section on the dotted
lines A B figure 2. Figure 8 is a transverse section of the body of the spirit level
with the enclosing plate and spirit tube removed. Figure 9 is a front and edge
view of the said enclosing plate.
The same letters of reference indicate corresponding parts in the several figures
of the Drawing.
a is the body or shell of the spirit level, partially closed at top, and open at
bottom. The said body in cross section resembles somewhat the figure of an
inverted letter U, with the spirit tube introduced into position from the underside,
instead of from the front, as is common with spirit levels of the ordinary construc-
tion ; so that the spirit tube is introduced into the box receptacle or compartment a²,
from the underside, which box portion is formed by dividing off the middle part of
the shell, as best seen in the longitudinal section figure 3; and situated near the
bottom edge of the gauge, two bearing seats a³ are provided, upon which the
enclosing plate b rests, which enclosing plate is affixed in position by small screws a¹
taking into the solid metal of the shell."
At the top of the gauge a is a longitudinal slit with a cross bar at its middle,
through which the spirit tube c is seen, the said tube being enclosed or affixed in
position by cement d, and protected by the plate b as before referred to.
Should at any time by accident or from other causes the spirit tube is required
to be replaced or taken out, this is done by simply removing the bottom or
enclosing plate.
In consequence of the bottom of the level being practically open, a thin edge d
is formed, which follows the boundary of the body of the shell a-This boundary
supporting edging is about an eight or a sixteenth of an inch broad.
The one and main advantage in having a hollow under body, with thin sup-
porting edges on its underside, is, that any inequalities being presented or coming
under the spirit level when in use, can be readily removed and a true bearing
obtained, by slightly shifting or shuffling the gauge.
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
First. Making spirit levels of a box or shell form divided or partitioned off at
or about its middle into a separate compartment, wherein the spirit tube is placed,
and introduced therein, from the back or underside, instead of from the front.
The closing up and securing of the said tube within the instrument is effected

page_text: by an enclosing plate, secured to seats or rests, substantially as described and
illustrated.
Secondly. Making the bases or the undersides of spirit levels, hollow, or partly
open or enclosed, so that the instrument when in use, rests wholly upon thin
supporting edges, which follow the outside boundary or base of the instrument,
substantially as and for the purpose herein-described and illustrated.
1
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1000