AN IMPROVEMENT IN QUADRANTS
Year: 1859

page_text: LETTERS PATENT to Thomas Hedgcock, of Ivy Cottage, Great Church
Lane, Hammersmith, in the County of Middlesex, Master in the
Royal Navy, for the Invention of "AN IMPROVEMENT IN QUADRANTS."
Sealed the 14th February 1860, and dated the 2nd September 1859.
PROVISIONAL SPECIFICATION left by the said Thomas Hedgcock at
the Office of the Commissioners of Patents, with his Petition, on the
2nd September 1859.
I, THOMAS HEDGCOCK, of Ivy Cottage, Great Church Lane, Hammersmith,
in the County of Middlesex, Master in the Royal Navy, do hereby declare
the nature of the Invention for "AN IMPROVEMENT IN QUADRANTS," to be as
follows:-
This Invention has for its object an improvement in quadrants, and consists
in an addition to the quadrant shown and described in the Specification of the
Patent granted to me, No. 727 (1855). That quadrant consists of a graduated
arc having radial arms attached to it at each end. These arms are both con-
nected with a boss at the centre of the arc through which an axis passes, and
it carries a moveable arm, having at one extremity a vernier, which slides in
contact with the graduated arc before mentioned; and at the other a silvered
glass, the surface of which is parallel with the length of the arm. Inter-
mediate of the length of one of the fixed arms, and in front of the silvered
glass before mentioned, is a glass which is silvered on one part and left trans-

page_text: parent on the other part. It is mounted on an axis, and can be set at any
angle to the arm which carries it by means of another graduated arc and an
arm carrying a vernier scale and mounted on the axis of the glass. In addition
to these glasses is a third glass, which is left transparent. It is carried by
the moveable arm, and is set at an inclination to the silvered glass thereon,
its lower edge coming almost in contact with the surface of the silvered glass.
This glass in the instrument described in my former Patent was fixed to the
moveable arm at an angle of 45° to the surface of the silvered glass.
Now, my present Invention consists in mounting this third glass on an axis
in such manner, that by means of a third graduated scale and an arm carrying
a vernier and fixed on the axis, such glass may be set at any desired inclination
to the surface of the silvered glass. This third glass should be so mounted as
to leave both its front and back edges clear. The instrument shown and
described in the Specification of my former Patent has also a level attached
to it, which is now dispensed with.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Thomas Hedgcock in the Great Seal Patent Office on the
2nd March 1860.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
HEDGCOCK, of Ivy Cottage, Great Church Lane, Hammersmith, in the County
of Middlesex, Master in the Royal Navy, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Second day of September, in the year of our Lord
One thousand eight hundred and fifty-nine, in the twenty-second year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Thomas Hedgcock, Her special licence that I, the said Thomas
Hedgcock, my executors, administrators, and assigns, or such others as I,
the said Thomas Hedgcock, 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
"AN IMPROVEMENT IN QUADRANTS," upon the condition (amongst others) that
I, the said Thomas Hedgcock, my executors or administrators, by an instru-
ment 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

page_text: 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 Thomas Hedgcock, 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 thereof, that is to say:-
This Invention has for its object an improvement in quadrants, and consists
in an addition to the quadrant shown and described in the Specification of the
Patent granted to me, No. 727 (1855). That quadrant consists of a graduated
arc having radial arms attached to it at each end. These arms are both con-
nected with a boss at the centre of the arc through which an axis passes, and
it carries a moveable arm, having at one extremity a vernier, which slides in
contact with the graduated arc before-mentioned; and at the other a silvered
glass, the surface of which is parallel with the length of the arm. Inter-
mediate of the length of one of the fixed arms, and in front of the silvered glass
before mentioned, is a glass which is silvered on one part and left transparent
on the other part. It is mounted on an axis, and can be set at any angle to
the arm which carries it by means of another graduated arc and an arm
carrying a vernier scale, and mounted on the axis of the glass. In addition to
these glasses is a third glass, which is left transparent. It is carried by the
movable arm, and is set at an inclination to the silvered glass thereon, its
lower edge coming almost in contact with the surface of the silvered glass.
This glass in the instrument described in my former Patent was fixed to
the moveable arm at an angle of 45° to the surface of the silvered glass.
Now, my present Invention consists in mounting this third glass on an axis
in such manner that, by means of a third graduated scale and an arm carrying
a vernier and fixed on the axis, such glass may be set at any desired inclination
to the surface of the silvered glass. This third glass should be so mounted as
to leave both its front and back edges clear. The instrument shown and
described in the Specification of my former Patent has also a level attached
to it, which is now dispensed with.
And in order that my said Invention may be most fully understood and
readily carried into effect,. I will proceed to describe the Drawing hereunto
annexed
Figure 1 is a front view, and Figure 2 is a back view, of a quadrant con-
structed according to my Invention. a is an arc fixed on arms b, b, radiating

page_text: from a boss c at the centre of the arc a; d is an axis at the centre of the
boss c; it carries the arm e, at the end thereof is the vernier scale e', which, as
the arm is moved on its axis, slides on the graduated arc a; this arc, as is
shown, is graduated, as is usual in quadrants, so that each degree of the
graduations on the arc corresponds with an angular motion of the arm e about
its axis equal to one-half of a degree. f is a piece which slides on the arc a,
it can be clamped thereto by the binding screw f', and g is a screw connecting
the extremity of the arm e with the piece f, and by turning this screw the
arm e may be moved through a short distance independently of the piece f;
by means of these parts the position of the arm e on the arc a can be accurately
adjusted. g* is a silvered glass carried by the arm e; its surface is parallel to
the length of the arm, and if continued would cut the zero point of the vernier
scale e'. is a glass which is partly silvered and partly left transparent; it is
mounted on an axis on one of the radial arms b, and this axis also carries an
arm i at the back of the instrument, the end of which has a vernier scale
formed on it, and slides when the arm is moved on an arc j, which is graduated
from a zero point in the centre of the arc towards each extremity thereof, each
degree of the graduation representing one-half of a degree of angular motion
of the arm i on its axis. The arm i is furnished with apparatus for locking it
to its arc, and with a screw for accurately adjusting it thereon, similar to those
employed in connection with the arm e, as already described. j* is an eye-
piece fixed on one of the arms 6 opposite the glass h; it has two small holes in
it, to one or other of which the eye is applied when observing. k is a trans-
parent glass mounted on the arm e; this glass, in the arrangement described in
the Specification of the Patent granted to me in the year 1855, is fixed to the
arm at an angle of 45° to the surface of the mirror g*, but according to my
present Invention it turns on pivots 1, 1; it has also an arm m attached to it,
and the end of this arm, as the glass k turns on its pivots, traverses over an
arc m* fixed on the arm e, and graduated with natural angles, as is shown, so
that by means of this are the glass k may be set at any desired angle to the
mirror 9*, and it may there be clamped by the binding screw m.
In witness whereof, I, the said Thomas Hedgcock, have hereunto set
my hand and seal, this Second day of March, in the year of our
Lord One thousand eight hundred and sixty.
THOMAS HEDGCOCK.