An Improved Traversing and Levelling Head for Theodolites or other Instruments.
Year: 1895

page_text: Date of Application, 8th Nov., 1895-Accepted, 14th Dec., 1895
An Improved Traversing and Levelling Head for Theodolites or
other Instruments.
We, ALEXANDER IRONSIDE LITTLEJOHN, and PETER STILL, both of 42 Lambton
Quay, in the City of Wellington, in the Colony of New Zealand, Scientific Instrument
Makers, do hereby declare the nature of this invention, and in what mannor the
same is to be performed to be particularly described and ascertained in and by the
following statement :-
The object of our invention is to provide a new and simple method of combining
and clamping together the traversing and levelling parts of a theodolite or similar
instrument, after the machine has been set, and of readily releasing the same for another
operation.
Our invention is illustrated on the accompanying sheet of drawings on which,
Figure 1 is a sectional view of our improved head as used for theodolites and similar
instruments.
Figure 2 is an elevation of part of the same when set to an angle and moved on the
traverse plate to its full extent.
Figure 3 is a plan showing the traversing plate, and
Figure 4 is a sectional view through the line 1-2 on Figure 1.
Similar letters indicate like parts in all the figures. (A) are the ordinary legs or
supports which are joined to the cap piece (a) by pins (A1). This cap piece (a) is
formed with a lower flange (a 1) and an upper flange (a 2), joined together by
distance pieces (a 3) so as to leave a free space in which the traversing plate (3)
may move freely in all directions horizontally. (c) is the traversing head having a
spherical upper surface (c 1) and flat base (c 2) so that it can be traversed horizontally
by the hand when desired simultaneously with the plate (b). (d) is the levelling head
fitted with the ordinary screw (d 1) for receiving the theodolite, which screw is covered by
a cap (e) when the instrument is not in use. This levelling head (d) has a base (d2)
hollowed out internally in the form of a sphere, so as to fit and move freely upon the
spherical surface (c 1) of the traversing head, and also has a projection piece (d 3)
fitted with a left-handed screw (d 4) for a purpose to be hereinafter described. The
cap (e) is fitted with a square recess (e 1) which forms a wrench for turning the joint
screws (A 1).
By this description of the parts it will be seen that an instrument screwed on
at (1) can be made to slide in any direction horizontally upon the base (c2), and
can be set to a horizontal position or to an angle by being adjusted on the spherical
surface (c 1). Such motions have been applied to theodolites and similar instruments,
and we lay no claim to the means which allow of such movements, our invention
consisting of the improved method of clamping the whole of the parts together,
and which we will now proceed to describe. (p) is the clamping piece, having at
its lower end a semi-spherical projection (p1), bored accurately to receive the
plumb-line (9), the centre of the semi-sphere being at (p2), which centre is also
the centre from which is described the spherical surface (c 1). This projection (p 1)
works accurately in a spherical hollow (1) formed in the traversing plate (b) t
receive it.
The upper end of the clamping piece (p) is formed in the shape of a capstan
head (p3) having an internal thread (p 4) screwing on to the thread (d 4) of the
levelling head (d) and around this capstan head are holes (p 5). (r) is a ring
fitting loosely around the levelling head (d) and fitted with two projections († 1)

page_text: which have internal threads to receive the screws (s), the ends of which (s1)
project into the holes (p 5) of the capstan head, and serve to turn the said capstan head
when the ring (7) is turned.
It will be seen from this description; of the several parts and by reference to the
drawings that the ring (r) being turned from left to right the capstan head (p)
is also turned, and by this action, (d 4) being a left-handed screw, the levelling
head (d) is drawn down tight upon the traversing head (c) and the traversing
plate (6) is drawn up against the plate or flange (a 2), so that both levelling head
and traversing head are firmly fixed by one action of the head acting on the
projecting pieces († 1), and this takes place in whatever position the levelling head
or traversing head may have assumed. Of course, on moving the ring (r) back
from right to left the whole is again loosened ready for re-setting. The point (p 2)
being the centre of the spherical traversing head (c), the plumb-line (9) is not
materially affected by the movement of the traversing head, but only by the horizontal
movement of the plate (a 1).
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is,
1. In a traversing and levelling head for theodolites and other similar instruments
a clamping piece (p) having a capstan head (p 3) acting upon the levelling head (d)
by means of the screw (d4), and having a tail-piece (p1) carrying the plumb
line (9), and oscillating or revolving in a traversing plate (b) as and for the
purposes substantially as described herein and illustrated.
2. In a traversing and levelling head for theodolites and other instruments a
clamping piece (p) having a capstan head (p3) acting upon the levelling head (d)
by means of the screw (d4) actuated by the revolution of a ring (r) carrying
screws or pins (s) as and for the purposes substantially as described herein and
illustrated.
3. The improved traversing and levelling head for theodolites or other instruments
substantially as specified.
Dated this 8th day of November 1895.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicants.