IMPROVEMENTS IN LEVELLING INSTRUMENTS
Year: 1883

page_text: LETTERS PATENT to Benjamin Joseph Barnard Mills of the firm of Harris
"
and Mills of 23 Southampton Buildings in the County of Middlesex, Patent
Agent for an Invention of " IMPROVEMENTS IN LEVELLING INSTRUMENTS
cominunicated to him from abroad by James Macdonald of the City County
and State of New York in the United States of America
PROVISIONAL SPECIFICATION left by the said Benjamin Joseph Barnard
Mills at the Office of the Commissioners of Patents on the 19th June 1883.
BENJAMIN JOSEPH BARNARD MILLS of the firm of Harris and Mills of
23 Southampton Buildings in the County of Middlesex, Patent Agent IMPROVE-
MENTS IN LEVELLING INSTRUMENTS. A Communication to me from abroad by
James Macdonald of the City County and State of New York in the United States
of America
The Invention relates to instruments for levelling long reaches of shafting and in
general to ascertain the deviation if any in altitude from the samo horizontal plane
of any two points situated at such a distance apart as to preclude the use of an
ordinary level.
For this purpose a flexible pipe and two liquid containing graduated portable
standards are employed in combination with peculiarly constructed valves and
coupling devices as hereinafter described.
The outer shell of each standard consists of a tube of brass or other metal secured
to a base and provided at opposite sides with vertical slots through which the
difference of an object in altitude above or below the horizontal line indicated by
the surface of the contained liquid is visible on a graduated scale marked on the
said tube at the edge of one of said slots or preferably upon a glass tube which
contains the fluid and which is fitted into a second metal tube slotted to correspond
with that first named and capable of turning therein.
To each end of the second metal tube is attached a conical valve.
The upper one of these valves is provided with a screwed cap and a vent hole
which when in one position communicates with the atmosphere through a corre-
sponding hole in the first metal tube and the lower valve at the same time opens a

page_text: communication through an arm with a flexible tube or hose by which the two
standards are connected together.
These holes or ports are closed or opened by applying the thumb and finger to
the milled edge of the cap and turning to the right or left until the movement
is restricted by a stop pin in the base which extends into a slot in the lower
valve.
These valves are so arranged as to open and close the communication between
the hose and the standards and the vent hole leading to the atmosphere at the
same time thus confining the water in the rubber hose and the air and water in the
standards simultaneously thereby rendering the instrument easily portable.
The second tube and the lower valve may be separated to give access to the glass
by removing a pin and the junction of the glass tube with the valves is rendered
watertight by means of india rubber or other suitable packing.
1
The hose is held upon and connected to the arm by means of a sleeve which fits
tightly upon the hose and is pushed or slidden over that part of the latter which 1
surrounds the arm which is threaded or grooved upon its circumference.
When the distance between the standards is so great as to render it necessary
to lengthen the hose by additional sections this is accomplished in the following
manner.
The adjacent ends of two hose sections are pushed over the outwardly threaded
or grooved surfaces of the tapering ends of a metallic coupling tube and corre-
sponding conical sleeves surrounding the ends of the said hose are employed to
compress the same against the grooved surface of the coupling tube.
In order to use the instrument the valves are opened, and one of the caps is
removed. Water is then poured into the uncovered standard in quantity sufficient.
to fill the standards and the hose or flexible connection between them to about the
middle of the scale.
The removed cap is then replaced and the valves are closed. The instrument is
now conveniently portable without spilling the liquid and ready for use.
To level two points the standards are placed in position and. the valves are
opened, thus opening the communication between the standards and the hose or
flexible connection and admitting air for equalizing the pressure on the two ends of
the liquid column and thus allowing the liquid to find its level.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Benjamin Joseph Barnard Mills in the Great Seal Patent Office
on the 19th December 1883.
33
BENJAMIN JOSEPH BARNARD MILLS of the firm of Harris and Mills of
23 Southampton Buildings in the County of Middlesex Patent Agent "IMPROVE
MENTS IN LEVELLING INSTRUMENTS A communication to me from abroad by
James Macdonald of the City County and State of New York in the United States
of America
The invention relates to instruments for levelling long reaches of shafting and
in general to ascertain the deviation, if any, in altitude from the same horizontal
plane of any two points situated at such a distance apart as to preclude the use of
an ordinary level.
For this purpose a flexible pipe and two liquid containing graduated portable
standards are employed in combination with peculiarly constructed valves and
coupling devices as hereinafter described.
And in order that the said invention may be more clearly understood and
readily carried into effect I will proceed aided by the accompanying Drawings more
fully to describe the same.
DESCRIPTION OF THE DRAWINGS
Figure 1 is a vertical section of one of the standards of a hydrostatic levelling
instrument constructed according to the invention, Figure 2 is a similar view but
showing the inner tube removed Figure 3 is a separate view of the inner tube
Figure 4 is a horizontal section taken on the line AA of Figure 1. Figure 5 is a
sectional plan taken on the line B B of Figure 1. Figure 6 is a separate view of
the cap and Figures 7 and 8 are separate sectional views of the upper and lower
valves respectively. Figure 9 represents the coupling device partly in section.
The outer shell a of each standard consists of a tube of brass or other metal
secured to a base a¹ and provided at opposite sides with vertical slots a³ through
which the difference of an object in altitude above or below the horizontal line
indicated by the surface of the contained liquid is visible on a graduated scale 6¹
marked on the said tube a at the edge of one of said slots or preferably upon a
glass tube b as shown which tube b contains the fluid and is fitted into a second
metal tube c slotted to correspond with the slots a³ in the standard tube a and
capable of turning in such tube a.
To each end of the metal tube c is fitted a conical valve c¹. The upper one of
these valves is provided with a screwed cap d and a vent hole c which when in
one position (as shown) communicates with the atmosphere through a corresponding
hole as in the tube a and the lower valve at the same time opens a communication
by its vent hole c³ through an arm a' with a flexible tube or hose e by which the
two standards are connected together. The cap d is formed with an annular
grooved communicating by a channel d' with the interior of the instrument and
it is provided with a flap valve d³ to close the channel d which will prevent the
liquid overflowing should one standard be raised higher than the other when
in use.
The vent holes or ports c³ are closed or opened by applying the thumb and
finger to the milled edge of the cap d and turning to the right or left until the
movement is restricted by a stop pin a³ in the base a' which pin extends into a
slot or groove o³ in the lower valve and extending partly around the same.

page_text: The valves c¹ are so arranged as to open and close the communication between
the hose e and the standards and the vent hole c in the upper valve and the
atmosphere at the same time thus confining the liquid in the rubber hose and the
air and liquid in the standards simultaneously thereby rendering the instrument
easily portable and preventing any air which may be contained in the standards
entering the rubber hose and mixing with the liquid therein which would
injuriously affect the proper working of the instrument.
and
The metal tube c and the lower valve c¹ are connected together by a pin
may be separated to give access to the glass tube b by removing such pin c and
the junction of the glass tube b with the valves is rendered watertight by means
of india rubber or other suitable packing.
The hoso e is held upon and connected to the arm a by means of a sleeve e¹
which fits tightly upon the hose e and is pushed or slidden over that part of the
hose e which surrounds the arm a' which arm is threaded or grooved upon its
circumference.
When the distance between the standards is so great as to render it necessary to
lengthen the hose by additional sections this is accomplished in the following
manner and as shown at Figure 9.
The adjacent ends of two hose sections are pushed over the outwardly threaded
or grooved surfaces of the tapering ends of a metallic coupling tube e² and
corresponding conical sleeves e' surrounding the ends of the hose e are employed
to compress the hose against the grooved surface of the coupling tube e².
In order to use the instrument the valves c¹ are opened that is to say they are
turned until their vent holes care opposite the ports a³ and a' in the standard
when their movement will be arrested by the stop pin a³. One of the caps d is 2
then removed and water is poured into the uncovered standard in quantity
sufficient to fill the standards and the hose or flexible connection between them to
about the middle of the scale.
The removed cap & is then replaced and the valves c¹ are closed by turning them
in the contrary direction. The instrument is now conveniently portable without
spilling the liquid and ready for use.
To level two points the standards are placed in position and the valves c¹ are
opened thus opening the communication between the standards and the hose or
flexible connection e and admitting air for equalizing the pressure on the two ends
of the liquid column and thus allowing the liquid to find its level.
Having thus described the nature of the said invention and the mode in which
the same is carried into effect I would have it understood that I do not claim
the general construction of the levelling instrument herein described but what I
do claim is: In a levelling instrument of the character herein described the
employment of valves constructed arranged and operating substantially as herein
shown and described and for the purpose stated.
In witness whereof I the said Benjamin Joseph Barnard Mills have hereunto set
my hand and seal this eighteenth day of December in the year of our Lord One
thousand eight hundred and eighty three
]
B. J. B. MILLS (L.S.)