IMPROVEMENTS IN ASTRONOMICAL AND SURVEYING INSTRUMENTS."
Year: 1876

page_text: LETTERS PATENT to Patrick Adie, of Pall Mall, in the County of Middlesex,
Mathematical Instrument Maker, for the Invention of "IMPROVEMENTS IN
ASTRONOMICAL AND SURVEYING INSTRUMENTS."
led the 21st December 1876, and dated the 30th June 1876.
PROVISIONAL SPECIFICATION left by the said Patrick Adie at the Office
of the Commissioners of Patents on the 30th June 1876.
PATRICK ADIE, of Pall Mall, in the County of Middlesex, Mathematical Instru-
inent Maker. "IMPROVEMENTS IN ASTRONOMICAL AND SURVEYING INSTRUMENTS."
The improvements relate to the manner of arranging the support of these instru-
ments when done by the means of three levelling screws, and for this I adopt the
following arrangements -Instead of having the three screws on which the instru-
ment is supported working in or through the tribrac frame I propose to make the
three screws a portion of said tribrac frame working in female screwed sockets,
which sockets have a ball or half ball worked on the lower part of their outer
side, the under spherical portions of which work in the V's of the tripod stand or
frame underneath. I thus am enabled to bring the fixed points of support in the
V's exactly into the same plane with the moveable screw contacts of the adjusting
screws, and so get rid of the angular displacement arising from the liability to
twist when the screw fittings are much above the points of support in the V's with
the milled head intervening, and the screws not a portion of the tribrac, but having
screwed fittings through the same. The upper extensions of the screwed adjusting
balls are worked into broad milled heads for turning the screwed sockets so as to
elevate or depress in levelling the instrument.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Patrick Adie in the Great Seal Patent Office on the 30th December
1876.
PATRICK ADIE, of 15, Pall Mall, in the County of Middlesex, Mathematical Instru-
anent Maker. IMPROVEMENTS IN ASTRONOMICAL AND SURVEYING INSTRUMENTS."
The improvements relate to the manner of constructing the supports of such
instruments when these are the three levelling screw patterns, and for this I
adopt the following arrangement:-Instead of having the three screws on which
the instrument is supported working in or through the tribrac frame I propose to
[Price 4d1

page_text: make the three screws a portion of the said tribrac frame working in female
screwed sockets, which sockets carry a milled head, and have a ball or portion of a
ball worked on the lower part of a hollow stem, extended underneath the milled
heads, the under spherical portions of which work in the V's of the tripod stand
or frame underneath. I thus am enabled to bring the fixed points of support in
the V's exactly in the same plane with the moveable screw contacts of the adjusting
screws, and so get rid of angular displacement arising from the liability to twist
when the screw fittings are elevated above the fixed points of support in the V's,
with the milled heads intervening, and the screws not a portion of the tribrac, but
having screwed fittings through the same. The upper portion of the screwed
sockets forming the milled head already referred to is used for turning the hollow
screwed sockets so as to elevate or depress, and so adjust.
But that the nature of my Invention and the means I adopt in carrying the
same into effect may be better understood, I will proceedto describe the Drawings
annexed, in both Figures of which the same letters are used to indicate like parts.
wherein they occur.
.
Fig. 1, A, A, A, is the tribrac of a theodolite or such instrument; B shows tho
hollow centre which receives the male centre, which carries the limb and upper
portions of the instrument not shewn in the Drawing. E, F, G, are the three
screws for supporting and levelling the instrument, these screws E, F, G, are not
adjustable through A at I, as is the usual way, but are of a piece, or fixed so as to
be of a piece with I.
Fig. 2 shews in section the arrangement which applies equally to E, F, and G,
with the attachment to the tribrac at A only shewn; C is a milled head; H, an
extension of C formed on the under side into a spherical shape; D, D, is the V on
which H rests; O, O, is a space turned out of C; P, P, is screwed to fit G. The
adjustment is made by turning C, by which means G is elevated or depressed,
thus the point of support of H being opposite the middle of the moveable femulo
adjusting screw P, P, the effect of torsion arising from the point of adjustment
being a long way above the point of support is wholly obviated.
A usual locking
plate, not shewn in the Drawing, comes over the top of H, to prevent the instru-
ment falling out of its V's.
Having thus described the nature of my said Invention, and the manner in
which I carry the same into effect, I would have it understood that I do not confine
myself to the precise details shewn and described as these may be varied, but what
I do claim is the bringing together to the same height or plane the point of support
and middle of the fitting of the adjusting screws, combined with the adjusting by
means of loose milled headed female screws attached to ball or segment of ball
instead of having these a portion of the adjusting screw itself, all substantially as
herein-before described and drawn.
In witness whereof, I, the said Patrick Adie, have hereunto set my hand
and seal, this Twenty-ninth day of December, in the year of our Lord One
thousand eight hundred and seventy-six.
PATRICK ADIE. (LS.)