An Improved Tripod or Legs for Theodolites.
Year: 1889

page_text: Date of Application, 26th Apr., 1889
Complete Specification Left, 20th Dec., 1889-Accepted, 1st Feb., 1890
PROVISIONAL SPECIFICATION.
An Improved Tripod or Legs for Theodolites.
I, THEODORE FREDERICK WIESENER of 334 George Street, in the City of Sydney
and Colony of New South Wales, Scientific Instrument Maker do hereby declare the
nature of this invention to be as follows:-
:-
This invention relates to tripods or supporting legs for theodolites and such like
philosophical instruments which require to be maintained in a set level position while
other parts are adjusted to a definite point, and it has been devised in order to provide
a tripod with a traversing head, neat in appearance, compact in construction, easy of
adjustment and very adaptable for carriage upon the shoulder.
Heretofore tripods for theodolites having traversing heads that is, heads whose
centres can be moved within certain limits so that the plummet can be adjusted over
the required point have not been constructed with legs which when folded together
form a ( circular stem."
My improved tripod is provided with such circular stem legs carrying a traversing
head which has free motion within certain limits in every direction. Each leg is
hinged by joints having wide or long bearings to an annular "bed plate" prepared or
faced both top and bottom. Upon a "stem" passing through the annular bed plate,
and between it and the hinge joints, is a clamp plate or piece. The said stem also
carries loosely a washer or face plate above the bed plate, and what may be termed a
clamp-nut" to which is screwed the foot of the instrument.
"
The stem may be either hollow or provided with a central hook at bottom, and the
usual cap is employed. Spaces are left between the bed plate and the hinge joints for
the working of the three legged or circular clamp plate. The stem is provided with
a head and with a shoulder having keys thereon. Stop pins are fitted on the washer
or face plate and the clamp piece has three legs. A thumb post is fixed to the clamp
nut to allow the same to be turned. The end of the clamp nut is screw threaded to
receive the theodolite.
In operation the tripod with the theodolite thereon is placed approximately above
the starting point and the instrument is then levelled. The plummet is then adjusted
by pressing the thumb post so as to turn the clamp nut on the screw thread of the
stem the stop pin preventing the thumb post from travelling round too far and thus
from doing more than loosening the clamp. The parts then consisting of the stem,
the three legged clamp piece, the washer and the clamp nut, the latter carrying the
instrument, are free to move upon the bed plate in any direction but within the limits
governed by the difference in the thickness of the stein and the internal diameter of
the annular bed plate. The legs of the clamp piece are free to move inwardly
outwardly and sideways in the spaces. The plummet then being adjusted to the
desired point by so moving the parts above mentioned-the nut by means of the
thumb post is screwed hard down and the head of the instrument is thus firmly
clamped to the bed-plate which latter being in this position a fixture with the legs,
has maintained the instrument level during the adjustment. By this means the legs
having been placed with the plummet approximately above the desired point within
the limits of the traverse of the head the said legs do not require moving during
adjustment and repeated adjustment of the levels of the instrument is avoided.
In a modification of my invention the revolution of the screwed stem in the clamp
nut (which now forms part of the washer or faceplate) is caused to tighten all the
parts.

page_text: COMPLETE SPECIFICATION.
An Improved Tripod or Legs for Theodolites.
I, THEODORE FREDERICK WIESENER, of 334, George Street, in the City of Sydney
and Colony of New South Wales, Scientific Instrument Maker, 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 tripods or supporting legs for theodolites and such like
philosophical instruments which require to be maintained in a set level position while
other parts are adjusted to a definite point, and it has been devised in order to
provide a tripod with a traversing head, neat in appearance, compact in construction,
easy of adjustment, and very adaptable for carriage upon the shoulder.
Heretofore tripods for theodolites having traversing heads, that is to say heads
whose centres can be moved within certain limits so that the plummet can be adjusted
over the required point, have not been constructed with legs which, when folded
together, form a "circular stem."
My improved tripod is provided with such "circular stem" legs carrying a
traversing head which has free motion within certain limits in every direction.
Each leg is hinged, by joints having wide or long bearings, to an annular "bed-
plate" prepared or faced both top and bottom. Upon a screw threaded "stem" or
stud passing through the annular bed-plate, and located between the latter and the
hinge-joints, is a three-legged clamp-plate or piece. The said stem also passes loosely
through a washer or face plate above the bed-plate and what may be termed a "clamp-
nut" to which is screwed the foot of the instrument.
In order to enable my invention to be fully understood I will describe how it can
be carried into practice by reference to the accompanying drawings, in which―
Figure 1 is an elevation of the upper part of a tripod for theodolites constructed
according to my invention.
Figure 2 is a plan of the same.
Figure 3 is a vertical section on the line a a figures 1 and 2.
Figure 4 is a horizontal section on the line bb figure 1.
Figure 5 represents a plan and a vertical section of the washer or face plate and
screw-threaded stem.
Figure 6 represents a plan and an elevation of the three-legged clamp-plate.
Figure 7 is a vertical section illustrating a modified form of my improved tripod
for theodolites.
Figures 8 and 9 are an elevation and a plan respectively of the screw-threaded stem
for the said modified form of tripod shewing the position thereon of the three-legged
clamp-plate and a trigger piece hereinafter described.
Similar letters in all the figures indicate similar or corresponding parts.
I will first describe my invention by reference to figures 1 to 6.
A, A are the metal legs of my tripod, which legs when closed together form a stem
of circular shape in cross section as will be most clearly seen by reference to
figure 4. B, B are the hinge-joints of the legs whereby the said legs are connected
to the annular bed-plate C.
The hinge pins B2 are fixed in lugs B₁ formed integral with the bed-plate Cand
shroudings or encasements A¹ extending from the eyes which receive the hinge pins
at the tops of the metal legs A serve to cover and protect the bearings of the hinge
joints. A A² are liners between which and the metal legs or cheeks A the wooden
legs A of the tripod are secured by means of screws.
D is the screw-threaded stem which may be either hollow as shewn, or provided
with a central hook at the bottom; F is the three-legged clamp-plate resting upon
a head DI formed on the lower end of the steun D, the legs of the clamp-plate F
working in spaces between the bed-plate C and the hinge-joints B. E is the
washer or face plate through which the stem D passes loosely, the said face plate

page_text: bearing upon the upper surface of the bed-plate C. G is the clamp nut with screw-
thread G on which the theodolite is screwed after the usual cap H is removed
therefrom. A thumb post G is fixed to the clamp nut G to allow the nut to be
turned and stop pins E2 are provided on the washer or face plate E against which
the post G can abut for the purpose of limiting the movement of the nut. D' is a
flange on the stem D, on which flange are projections E¹, E¹.
In operation the tripod with the theodolite thereon is placed approximately above
the starting point and the instrument is then levelled. The plummet is then adjusted
by pressing the thumb post G' so as to turn the clamp nut G on the screw thread
of the stein D, the stop pin E2 preventing the thumb post from travelling round too
far and thus from doing more than loosening the clamp F. The stem D, the
three-legged clamp-piece F, the plate E and the clamp nut G (the latter carrying
the instrument) are then free to move upon the bed-plate C in any direction but
within the limits comprised by the difference in the thickness of the stem D and
the internal diameter of the annular bed-plate C. The legs F' of the clamp-piece F
are free to move inwardly, outwardly and sideways in the spaces C¹. The plummet
then being adjusted to the desired point by so moving the parts above mentioned,
the nut G by means of the thumb post G₁ is screwed hard down and the head
of the instrument is thus firmly clamped to the bed-plate which latter, being in this
position à fixture with the legs, has maintained the instrument level during the
adjustment. By this means the legs having been placed with the plummet
approximately above the desired point within the limits of the traverse of the head,
the said legs do not require moving during adjustment and repeated adjustment of
the levels of the instrument is avoided.
In the modification of my invention illustrated in figures 7, 8 and 9 the revolution
of the screw-threaded stem D in the clamp nut G (which here forms part of the
washer or face-plate E) is caused to tighten all the parts.
The flange D of the stem D is fitted with a trigger-piece I adapted to be fixed
thereto by means of set screws J, J which enter a groove K forined in the said
flange. The trigger-piece I projects outside through an opening L in the clamping-
nut G, so as to enable it to be moved in order to loosen the clamp F and the nut G
to which the theodolite is screwed instead of turning the clamp nut by means of a
thumb post thereon as in the arrangement illustrated in figures 1 to 6. In other
respects the construction of the tripod is the same.
In order to change the traversing or face plate E, after first loosening the clamp F
by means of the trigger-piece I as described the set screws J, J must be loosened and
the stem D being firmly held by tightly jamming a tapered or other suitably shaped
piece of wood into the central passage of the same from below, the traversing plate
can then be unscrewed. The handle end of a screw-driver with which each
instrument is supplied can advantageously be used for this purpose. The trigger-
piece I must then be introduced through the slot L of the substituted plate, the
stem D passed through the trigger-piece and the stem D being still firmly held by
the means herein before described, the traversing plate is screwed thereon until it is
firmly clamped. The trigger-piece is then shifted to the middle of the opening L
and the set screws J, J are tightened.
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 tripod for theodolites having a traversing head supported by and upon legs
which, when closed together, form a circular stem, substantially as hereinbefore
described.
2. The means for clamping the screw-threaded base of a theodolite to a bed-plate
jointed to the legs of the tripod and for loosening the clamp from above for the
adjustment of the instrument without disturbing its level, substantially as hereinbefore
described.

page_text: 3. In a tripod for theodolites the combination with legs jointed to a bed-plate, of a
three-legged clamp-piece which works in spaces C¹ and a screw-threaded stem or stud
with or without
separate face-plate or washer and the clamp nut to which the
instrument is screwed substantially as herein before described and illustrated in the
accompanying drawings.
4. The improved tripods or legs for theodolites herein before described and
illustrated in the accompanying drawings.
Dated the 20th day of December 1889.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.