A Novel Self-adjusting Levelling Instrument.
Year: 1893

page_text: Date of Application, 13th Feb., 1893
Complete Specification Left, 13th Nov., 1893-Accepted, 16th Dec., 1893
PROVISIONAL SPECIFICATION.
A Novel Self-adjusting Levelling Instrument.
I, HENRY BLACKHAM, of Lichfield Street, Wolverhampton in the County of
Staflord, Optician, do hereby declare the nature of this invention to be as
follows :-
This invention has for its object the construction of a levelling instrument
which shall be self-adjusting, that is to say in which the portion through or by
means of which the sight is taken shall automatically assume a true level when the
legs or frame by which it is supported have been placed in position for the
purpose of taking a sight, whereby considerable economy of time is effected
compared with the use of ordinary levelling instruments in which screws have to
be manipulated to secure the necessary adjustment.
A levelling instrument constructed according to this invention has the portion
thereof through or by means of which the sight is taken suitably pivoted, so that
it can be moved through a vertical or approximately vertical arc, to a turning
piece which is carried in a mounting to which the supporting legs are attached in
such manner that it can turn in such mounting and allow of the portion through
or by means of which the sight is taken being turned to any point of the compass.
A pendulum is rigidly connected with the portion of the instrument through or
by means of which the sight is taken, and such portion is thereby automatically
brought to a true level in the direction into which it may have been moved after
the instrument has been set up.
A more complex form of the apparatus consists in constructing it as above
described except that the portion through or by means of which the sight is taken
is pivoted to a ring which is itself pivoted to the turning piece on an axis at right
angles to the axis on which the portion through or by means of which the sight is
taken is pivoted to the ring. According to this latter construction, the portion
through or by means of which the sight is taken will always automatically
assume, when the instrument is set up, a true level in the direction in which such
portion is turned, and the transverse axis on which it is pivoted to the ring will
automatically assume a true level also.
An instrument may be constructed, according to this invention, suitable for
being held in the hand for roughly sighting levels. In such an instrument the
legs or frame and mounting at the top thereof as described are dispensed with,
and a part corresponding to the part above described as the turning piece is
adapted to be grasped and held by one or both hands, by which means it is held
approximately steady while the pendulum comes to rest and the sight is taken.
Dated this 11th day of February 1893.
STEPHEN WATKINS,
Wolverhampton, Agent for the Applicant.
COMPLETE SPECIFICATION.
A Novel Self-adjusting Levelling Instrument.
I, HENRY BLACKHAM, of Lichfield Street, Wolverhampton in the County of
Stafford, Optician, 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 has for its object the construction of-a levelling instrument which
shall be self-adjusting, that is to say, in which the portion through or by means

page_text: of which the sight is taken shall automatically assume a true level when the legs
or frame or other part by which it is supported have or has been placed or is in
position for the purpose of taking a sight, whereby considerable economy of time
is effected compared with the use of ordinary levelling instruments in which
screws have to be manipulated to secure the necessary adjustment.
A levelling instrument, constructed according to this invention, has the portion
thereof through or by means of which the sight is taken suitably pivoted to the
part by which it is supported so that it is free to move into a true level from any
other position when the instrument is set up for taking a sight; and the self-
adjustment is effected by means of a rod or stem, having an enlargement or weight
on its lower end, which is rigidly connected with the portion of the instrument
through or by means of which the sight is taken.
A self-adjusting levelling instrument, constructed according to this invention, is
illustrated by the drawings herewith, of which
Figure 1 is a part side elevation and part section, Figure 2 a vertical section
through the centre taken at right angles to the view shewn by Figure 1, and
Figure 3 a plan with the telescope barrel removed.
In Figure 1 the outer end of the telescope is omitted and the inner end of the
barrel is broken away for convenience of illustration; the upper portions only of
the supporting legs are shewn, and the rod or stem having an enlargement or
weight at its lower end is broken in its length. In Figures 2 and 3 the supporting
legs are omitted, and in Figure 2 the rod or stem is broken in length as in
Figure 1.
The carrier or bar A, in the jawed or bifurcated ends of which the telescope
barrel B is fixed in the ordinary manner, is pivoted by means of pivots a within
bearings formed in blocks 6 projecting upwards from a ring C, and the pivots are
preferably covered with caps c. The axis of the pivots a is transverse to the
axis of the telescope and thus, when such axis is truly horizontal, the longi-
tudinal axis of the telescope may be moved through a vertical arc. The ring C is
pivoted by means of pivots d within a bush or turning-piece D which is made a
true turning fit within the mounting E to which the upper ends of the tripod legs F
are pivoted. This bush D allows of the telescope being turned to any point of the
compass. The axis of the pivots d is at right angles to the axis of the pivots a, and
thus the transverse axis of the telescope may be moved into any required angle
with the vertical axis of the bush. The bush D has a collar e therearound at the
top which rests upon the top of the mounting E. The pivoting of the ring C
within the bush D is conveniently effected by forming the pivot pins d each with a
screwed outer end and a plain inner end, and screwing the pins into holes in the
collar e with their plain ends within holes which form bearings in the ring. The
left hand side of the ring C is shewn in section by Figure 1, while the remainder
of the ring is shewn by such view as in outside elevation. A stem G, having an
enlarged or weighted lower end f, is screwed or otherwise rigidly fixed to the
carrier A from the centre of which it depends when the instrument is set up. The
stem passes down through the ring C bush D and mounting E, and the legs Fare
pivoted to the mounting each at such distance from the vertical axis thereof that
they may be closed up against one another at their lower ends notwithstanding
that the legs are closed up around the enlargement or weight f.
It will readily be seen that when the instrument is set up, the rod or stem G
enlarged or weighted at its lower end will hang down perpendicularly, as the
carrier A and rod or stem are connected to the supporting bush D by a universal
joint having its two pivot axes at right angles to one another. The telescope is,
of course, so adjusted in relation to the rod or stem that when the latter is at rest
after the instrument is set up both the longitudinal and transverse axes of the
telescope are truly horizontal. The instrument is thus self-adjusting.
As in the case of other constructions of levelling instruments in which a bush or
turning piece corresponding to the bush D is used, a shallow groove g is turned
in the outer surface of the bush into which the end of a pin h, screwed through

page_text: the side of the mounting E, is advanced to prevent the bush being accidentally
removed from the mounting; and in this case also the bush may be fixed from
turning in the mounting by screwing the pin h tightly against the back of the
groove. When the pin his unscrewed sufficiently to withdraw its end from the
groove g, the bush D may be lifted out of the mounting E, and the mounting is
preferably of such internal diameter that the enlargement or weight f may be
drawn up therethrough, so that the telescope, carrier A, stem G and enlargement
or weight at its lower end, ring C and bush D, may be removed, without
disconnecting any of them from the rest, for packing separately from the tripod.
The upper portion of the mounting E may be made separately from the lower
portion to which the legs are pivoted, and be joined thereto by a screwed joint i.
In the illustrations, the portion by means of which the sight is taken is shewn
as a telescope, but it may consist of other appliance fitted with sights, such as
that used with a miner's or latching dial, the rod or stem G being rigidly fixed to
or connected with such portion so that when it comes to rest after the instrument
is set up the sights will be truly horizontal.
A simpler, but less reliable, form of levelling instrument may be constructed
by pivoting the portion through or by means of which the sight is taken direct to
the bush D, the pivot axis being transverse to the longitudinal axis of the sighted
portion.
An instrument may be constructed, according to this invention, suitable for being
held in the hand for roughly sighting levels. In such an instrument, the legs or
frame and mounting at the top thereof as described are dispensed with, and a part
corresponding to the bush D is adapted to be grasped and held by one or both
hands, by which means it is held approximately steady while the rod or stem G
comes to rest and the sight is taken.
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.:-
1. A self-adjusting levelling instrument in which the adjustment is effected by
means of a hanging weight, substantially as described.
2. A self-adjusting levelling instrument in which the portion through or by
means of which the sight is taken is connected with the fixed portion by a universal
joint, and is brought to a true level, when the instrument is set up, by the coming
to rest of a rod or stem enlarged or weighted at its lower end with which it is
rigidly connected, substantially as described.
3. A self-adjusting levelling instrument constructed and operating substantially
as described and shewn by the drawings herewith.
Dated this 11th day of November 1893.
STEPHEN WATKINS,
Wolverhampton, Agent for the Applicant.