IMPROVED INSTRUMENTS FOR ASCERTAINING LEVELS, ALSO FOR COMPUTING ANGLES
Year: 1863

page_text: PROVISIONAL SPECIFICATION left by William Edward Gedge at the
Office of the Commissioners of Patents, with his Petition, on the 17th
September 1863. - A communication from abroad by Jean Baptiste
Chairgrasse, of Dijon, France.
I, WILLIAM EDWARD GEDGE, of the Firm of John Gedge and Son, of No. 11,
Wellington Street, Strand, in the County of Middlesex, Patent Agent, do
hereby declare the nature of the said Invention for "IMPROVED INSTRUMENTS
FOR ASCERTAINING LEVELS, ALSO FOR COMPUTING ANGLES," a communication to
me from abroad by Jean Baptiste Chairgrasse, of Dijon, France, to be as
follows:-
The improved levels, the subject of this Invention consist of the ordinary
simple level, combined simple ordinary and incline level, and combined simple
ordinary incline graphometer and square level. The thee pocket levels aro
composed each of a small board either of wood, and nearly half an inch thick,
to a plate of any metal the sixth or fourth of an inch thick, and about nine
inches in length by six inches in breadth, cut away at each angle by way of
ornamentation only by portions of circumferences having say, one inch in
diameter. The board or plate carries two inner cuts or hollows one forming a
little more than a quarter of a circle and one inch broad for the movement
of a small copper (or other metal) plummet, and the other to enable the
instrument to be held with greater facility. The dimensions of the board or
plate and of the radius of the plummet thread may be increased up to twenty
inches on the square by one thick. The divisions marked on the board or

page_text: plate indicate the numbers or figures corresponding with the different inclina-
tions. This designation may be inscribed in full letters on the levels, and
may be marked on a metal stamp fitted to the plate. The cyphers of the other
divisions indicate the incline by yard. The small divisions indicate the inclines
inch by inch, or part of inch, which may be continued on the entire extent
of the quarter circle. To settle these divisions the right angle is brought
completely from the left angle where all the lines of inclination converge, and
similarly with all the others. The plunmet will be suspended by means of a
horsehair or silken cord crossing the board or plate by means of a small
copper tube. The combined simple ordinary and incline level is composed of
the board or plate, above described with the plummet line, and also two pinules
or sight vancs, one with hole the other with window. These two pinules, which
are forked, are placed at the upper part of the board or plate and fixed by a
screw. The board or plate may be fixed, on a ball and socket of wood or
metal. The graphometer level is composed of a plate. of wood, copper, or
other metal, say, about nine inches long by nine inches high, measured from
the upper line to the vertical extremity of the diameter. If of wood it will be
about one inch thick, if of metal, one-fourth to one-sixth of an inch. It will
be cut away at the upper part like the other levels, it will have but one inner
cut or hollow of a little more than a quarter circle with a radius of about five
inches which may be increased or diminished with one inch in length for the
plummet. The lower part will be à circumference having exteriorly a diameter
of about eight inches, on which will be traced the degrees and balf degrees of
the circle. This instrument, like the preceding, is fixed on a ball and socket,
and when the board or plate is horizontal the altitudes act as square and as
graphometer, therefore the last described instrument fulfils the same purpose as
those previously described, and further acts as a graphometer.