An Improvement in Portable Theodolites, Levels, and other Surveying Instruments.
Year: 1899

page_text: PROVISIONAL SPECIFICATION.
An Improvement in Portable Theodolites, Levels, and other Surveying
Instruments.
GEORGE ALFRED HALL, 1, Victoria Street, Westminster, S.W., Architect and
Survevor, do hereby declare the nature of this invention to be as follows:-
An improvement in portable theodolites and levels consisting of an entirely
new ball & socket adjustment. A rectangular telescope with cross webbs and stadía
lines for reading levels and distances can be used separately or may be attached to a
clamp rest which forms the upper hemisphere of
a metal ball. This
upper half is hollow & leaves only three bridging pieces which act
as the support and admits of a compass with an "all way" spirit level combined &
sunk into the lower half of the ball being read. There is a vertical & horizontal
circumferenter with verniers & microscopes attached to the telescope and socket
in which the ball support works respectively and which gives vertical or horizontal
angles as required. The ball can be set to any position by the means of a clamp-
ing screw in the lower part of the socket. The telescope is set to a true level by
means of a spring clip & a slow motion screw.
Dated this 9th day of February 1899
An Improvement in Portable Theodolites, Levels, and other Surveying
Instruments.
GEORGE ALFRED HALL, 1, Victoria Street, Westminster, S.W., Architect and
Surveyor, 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:-
"
An improvement in portable theodolites and levels consisting of an entirely
new ball & socket adjustment. A rectangular telescope with cross webbs & stadia
lines for reading levels & distances & which can be used separately or by attaching
to it a clamp rest which forms the upper hemisphere of a metal ball. This upper
hemisphere is hollow & leaves only the bridging pieces which act as the support &
admits of a compass with an all way" spirit level combined & sunk into the lower
half of ball being read. There is a vertical & horizontal circumferenter with
verniers & microscopes attached to the telescope & socket in which the ball support
works & gives vertical or horizontal angles as required. The ball can be set to
any position by the means of a clamping screw in the lower part of the socket.
[Price 8d.]

page_text: The telescope is set to a true level by means of a spring clip & a slow motion screw.
The telescope is connected to its support on a swivel neck having a spring stop
so as to revolve horizontally without losing its level.
The body of the instrument a is a square metal tube less than 1/16" thick. A
circular focussing tube with rachet motion contains a disc with 1 vertical and two
horizontal stadia wires or webbs spaced to read for every 100ft. distant
foot on
the levelling staff. Telescoped to the focussing tube is an eye piece b. To the
reverse end of the square tube is the object glass screwed in making a complete
lens telscope. A metal plate c is tapped and screwed to the body and shaped to
a semi-circle on which the degrees are graduated reading to minutes by means of
a magnifier d and vernier e. The vernier is centred through the milled head f
and the centre spindle is fixed on the inner side of the are or semi circle to a
cross piece which supports a cylindrical spirit level with adjusting screws at each
end so that the vernier may be kept accurately at right angles with the level.
Form out of similar square tubing the rest g, open on one side to allow the screw
focussing adjustment to the telescope to slide through. Form a shoulder tapped
to receive the screw h, which secures the telescope in its rest. Screw to the top of the
rest the plate t, to which it attached the spring, and at the other end the screw,
to form the slow motion adjustment for setting up true level. Form of 3/8" metal
the round neck j, with reduced top fitted to plate p, and carried through to the
bottom of the rest'y, and to the plate p, fix a spring clip so that the telescope may be
revolved for reading back and front levelling staffs. The base of the neck j is
welded through the centre where the bridging pieces k, k, k converge. These
bridging pieces are turned in a lathe with the lower hemisphere and afterwards
detached but again sunk into the sides of the lower half and secured with
screws the heads being accurately filled so that the whole may revolve in the
socket m, easily and truly for the purpose of taking vertical and horizontal angles
or any other angles. Turn in the centre of to a depth of 3/8" and to a diameter
of 11" a sinking to receive the compass plate and needlen and the spirit level o
with glass bottom and top so that the compass may be read through the level. Form
a German silver circumferenter 9 graduated to 360 degrees and reading to minutes
with the vernier r, which is hinged to the moveable sphere so that it can be folded
Lack when vertical angles are required to be taken. The circumferenter is screwed
to the cup m & above the meridian so as to keep the ball in the socket. Turn
a thread "w" for 1/4" screw in the base of the socket by which means it is attached
to its aluminum tripod stand.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that
what I claim is:-
1. The adoption of the ball and socket action as described above for obtaining
levels.
2. The combination of compass and spirit level as described above.
3. The disposition of the stadia wires for measuring distances without the aid of
a chain and tape in so small an instrument.
Dated this 28th day of October 1000.
GEORGE ALFRED HALL