IMPROVEMENTS IN DRAWING AND LEVELLING INSTRUMENTS."
Year: 1858

page_text: LETTERS PATENT to François Auguste Lecornu, of Paris, (France,)
Mechanician, for the Invention of "IMPROVEMENTS IN DRAWING AND
LEVELLING INSTRUMENTS."
Sealed the 5th October 1858, and dated the 10th April 1858.
PROVISIONAL SPECIFICATION left by the said François Auguste Lecornu
at the Office of the Commissioners of Patents, with his Petition, on
the 10th April 1858.
I, FRANÇOIS AUGUSTE LECORNU, of Paris, (France,) Mechanician, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN DRAWING AND
LEVELLING INSTRUMENTS," to be as follows:-
The Invention consists of a rule provided with suitable divisions and with a
notch of such length that the hypotenuse of an isosceles or equicrural triangle
may be inserted therein, so as to have its right angle in a vertical position, in
which angle is a plumb line or pointer. The three sides of the triangle are
provided with suitable divisions in order that the whole may serve as an
instrument for indicating the level or any degree of inclination; the said rule
and triangle may serve also as drawing instruments, and the same may be
adapted to any instrument in which a rule and level are required.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said François Auguste Lecornu in the Great Seal Patent Office
on the 9th October 1858.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, FRANÇOIS
AUGUSTE LECORNU, of Paris, France, Mechanician, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Tenth day of April, in the year of our Lord One
thousand eight hundred and fifty-eight, in the twenty-first year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
François Auguste Lecornu, Her special licence that I, the said François
Auguste Lecornu, my executors, administrators, and assigns, or such others
as I, the said François Auguste Lecornu, my executors, administrators, and
assigns, should at any time agree with, and no others, from time to time
and at all times thereafter during the term therein expressed, should and
lawfully might make, use, exercise, and vend, within the United Kingdom
of Great Britain and Ireland, the Channel Islands, and Isle of Man, an
Invention for "IMPROVEMENTS IN DRAWING AND LEVELLING INSTRUMENTS," upon
the condition (amongst others) that I, the said François Auguste Lecornu,
my executors or administrators, by an instrument in writing under my, or
their, or one of their hands and seals, should particularly describe and
ascertain the nature of the said Invention, and in what manner the same
was to be performed, and cause the same to be filed in the Great Seal
Patent Office within six calendar months next and immediately after the
date of the said Letters Patent.
NOW KNOW YE, that I, the said François Auguste Lecornu, do hereby
declare the nature of the said Invention, and in what manner the same is
to be performed, to be particularly described and ascertained in and by
the following statement:―
The Invention consists in an apparatus in which certain indications are
given by means of a plumb line, and which for itself may be used either as a
drawing or levelling instrument, or applied to other graphical instruments
instead of the water or other level with which such instruments where hitherto
furnished.
In the annexed Drawings Fig. 1 gives an elevation view of the apparatus
which may serve either as a drawing rule or for indicating either a level or
certain angles, and will be found exceedingly useful for architects, engineers,
and others. The same consists of a rule A, F, which I prefer constructing of

page_text: brass, iron, or any other metal or material that preserves its forms and
dimensions, this rule may have divisions of any kind inscribed thereon so as to
allow of making use of the same as a measure or as a drawing rule, or the
same may be arranged as a calculating rule. On this rule is either fixed or
applied in any suitable manner the two sides B, C, and B, D, of an isosceles
or equicrural triangle or square, so as to cause the rule A, F, or part C, D, of
the same to form the hypotenuse of the square; and if now a plumb line G, H,
be applied to the centre of the right angle C, B, D, this plumb line will when
the rule is situated at exact level point to the centre I of that part of the rule
which forms hypotenuse, that is, the part extending from C to D. To one or
both of the arms B, C, and B, D, may be applied a segment of a circle, as
shown in Fig. 1, provided with suitable divisions for indicating the grade or
inclination under which the rule might be placed when the apparatus is to
serve as a levelling or graphical instrument. The arms B, C, and B, D, may
themselves be provided with proper divisions. It may in some cases be useful
to have the square B, C, D, form a separate part, and cause the same to glide
in a slot or groove in the rule A, F. In Fig. 2 a top view of the apparatus is
shown, provided with two or three fixed or moveable sight vanes L, so as to
make the rule form alidade, and if required the ordinary telescopes made use
of for graphical instruments might also be applied to the rule. Fig. 3 shows
in elevation view the apparatus applied to a graphical instrument (for instance,
to an astrolabe), in order to serve instead of the ordinary water level hitherto
made use of in such instruments; Fig. 4 shows an elevation view of a modifi-
cation of Fig. 1. In Fig. 1 the plumb line G, H, is hung from the point G,
whereas in Fig. 4 the apparatus is provided with a top K, forming an arc of a
cercle, in the interior of which turns in a concentric manner round a swivel or
axis p the segment P, to the lower part of which is fixed the plumb
line R; the arc K and the segment P are further provided with proper cor-
responding divisions so as to form a vernier or nonius, whereas the plumb line
will indicate on the divided arc S, T, the angle which the rule of the instru-
ment forms with the horizontal or level line; the entire may be fixed in the
same manner as in Fig. 3 on a proper foot or stand.
Having thus described the nature of my Invention, and the manner of
carrying the same into effect, I would observe that I do not limit myself to
the precise details herein-before described, as they may be modified without
departing from the principle of the Invention; but I claim the general
arrangement of the apparatus described, forming a commodious instrument
for drawing, levelling, and other analogous operations, or which may in many

page_text: instances replace the ordinary water levels hitherto made use of in graphical
instruments.
In witness whereof, I, the said François Auguste Lecornu, have hereunto
set my hand and seal, this Seventh day of October, One thousand eight
hundred and fifty-eight.
Witness,
J. SOUTH.
A. LECORNU. (L.S.)