CERTAIN IMPROVEMENTS ON OR ADDITIONS TO THE ASTRONOMICAL INSTRUMENT, KNOWN BY THE NAME OF THE QUADRANT
Year: 1822

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
BENTON ROXBY, of Arbour Square, Stepney, in the County of Middlesex,
Gentleman, send greeting.
WHEREAS His most Excellent Majesty King George the Fourth, did, by
His Letters Patent under the Great Seal of that part of the United Kingdom
of Great Britain and Ireland called England, bearing date at Westminster, the
Thirty-first day of July, in the third year of His reign, give and grant unto
me, the said Robert Bentón Roxby, my exors, admors, and assigns, His
especial licence, full power, sole privilege and authority, that I, the said
Robert Benton Roxby, my exors, admors, and assigns, during the term of
years therein mentioned, should and lawfully might make, use, exercise, and
vend, within England, Wales, and the Town of Berwick-upon-Tweed, my
Invention of "CERTAIN IMPROVEMENTS ON OR ADDITIONS TO THE ASTRONOMICAL
INSTRUMENT, KNOWN BY THE NAME OF THE QUADRANT;" in which said Letters
Patent there is contained a proviso, that if I, the said Robert Benton Roxby,
shall not particularly describe and ascertain the nature of my said Invention,
and in what manner the same is to be performed, by an instrument in
writing under my hand and seal, and cause the same to be inrolled in His
Majesty's High Court of Chancery, within two calendar months next and
immediately after the date of the said Letters Patent, that then the said*
Letters Patent and all liberties and advantages whatsoever thereby granted
shall utterly cease, determine, and become void, as in and by the same, relation:
being thereunto had, will more fully and at large appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
Robert Benton Roxby, do hereby declare that my improvements upon the
astronomical instrument, commonly called a quadrant, are herein set forth
and explained, reference being made to certain parts of the Drawing hereunto
annexed (that is to say):--
But previous to describing the improvements I have invented, I shall here
observe that a great deal of inconvenience and difficulty is experienced by all
mariners in the use of the Hadley's quadrant on account of the liability there
is in all of them to move by starts or jumps (particularly in damp weather),
in which case it becomes exceedingly difficult and sometimes almost impossible
to make an accurate observation, because the index so frequently overshoots.
the precise place at which it should come to rest. To remedy this incon-
venience a tangent screw was applied to the index or nonius, by which means
a fine adjustment can be obtained, but in all cases where an observation is
to be made, it is necessary the index should be moved by the hand only as
near as possible to the desired position, when the index (in quadrants that
have a tangent screw) must be clamped, and then the tangent screw is
made use of to complete the observation. Now it must have been found
by every person conversant with nautical practice that such a loss of time
occurs in the use of the tangent screw that the opportunity is frequently lost
by observing the sun at the meridian, and that at a time perhaps when it is
of the most serious consequence to the lives and property of a numerous
body of people. It also frequently happens that when a view of the sun
can be obtained while at the meridian, no use can be made of it, because the
borizon cannot be perceived on account of the hase that then prevails.
This unfortunate circumstance is too often experienced, and for want of an
observation, the most distressing consequences ensue. Various attempts have
been made to construct an artificial horizon, which should serve as well as
the natural horizon, but up to the present time no one has been produced that
would sufficiently answer the purpose so as to be implicitly depended upon.
I shall now proceed to shew how the improvements I have invented will
enable any person to take a very accurate observation whenever the sun can
be seen at the meridian, whether the natural horizon be visible or not.
Fig. 1, A, A, represents a front elevation of a quadrant, of the size that I
prefer when my improvements are to be combined therewith; B, shews a
square plate of brass, screwed by the screws a, a, a, a, to a similar shaped
piece of ebony, which constitutes a portion of the frame A, A, of the instru-
ment. To this piece of brass the parts which form my artificial horizon are

page_text: fixed; G shews the position of the horizon glass, which I find convenient to
place lower down than is usually done; the same alteration is also adopted
with the sight vane D; E represents a piece of brass, which swings freely
upon a small brass pin b, and is secured there by the milled head c; 'the
piece E has a projecting arm F, upon the end of which is fixed the small
angular projecting piece d; which I call the director or finder, the edge or line
formed above d, at e, being one of the lines which I use to find the place of
the true horizon'; G represents' a piece of brass which fits into a 'square liole
in the stud piece f, where it may be held at any height by the thumbscrew 9;
h shews the possition and shape of a small projecting stud, which has a gap
filed in it, shewn by a dotted line near h, the line thus formed at the bottom-
of the gap is used as a guide to the eye of the observer, to bring the finder or
director to a proper place. Fig. 2 shews a plan or birds'-eye view of the
finder or director, seen at E, Fig. 1. Fig. 3 represents a front elevation of
the finder or director, with the same letters of reference upon the parts thereof
that were used in Fig. 1. Fig. 4 shews a side view of Fig. 2. Fig. 5 shews
a left-hand side view of the guide piece, shewn at G in Fig. 1; and Fig. 6
shews a right-hand side view of the same piece, the form of the gap will, in
these two Figures, be very distinctly seen at h. Fig. 7 is a plan or birds'-eye
view of the same piece. Fig. 8 shews a plan of the stud or arm f, which holds
the guide piece shewn at G, Fig. 1. Fig. 9 shews a plan of the brass pin b,
and milled head c, upon which the director or finder E swings.
Having enumerated the various parts, and shewn the combination of that
portion of my Invention which enables me to form an artificial horizon, I shall
now endeavour, as briefly as possible, to explain the manner of adjusting and
using the same with the greatest advantage. When the instrument with my
improvements is to be, adjusted, it must be placed upon the three bearings
seen at H, I, J, Fig. 1, the last of which also forms a handle to hold 'the
instrument by when it is used, this is fixed upon a brass pin about three inches
long, by the screw i; the surface upon which the quadrant is placed must be
varied in position until the line formed above the angular piece at e, coincides
with the real horizon; this being very accurately obtained, the instrument
must be left at rest, and the brass guide piece G being placed properly in the
hole or recess provided for. it in the stud. f, must be so adjusted for height
that a very minute line or portions of the part d of the director E may be seen
above the line h, formed by the bottom of the gap in the guide piece G; the
line k, drawn from the sight vane D to the part d of the director E, shews
that it is a very minute height above the line formed at the bottom of the

page_text: gap h, in the guide piece G, and as the line k cuts or passes through the
horizon glass at k, it there shews the true place of the real horizon.
When the instrument is to be used to take an observation at a time that the
real horizon cannot be seen, it must be held in the left hand by the handle J,
and the eye being placed at the sight vane D, the quadrant must be moved in
such a manner that the line formed by the upper part e of the director E, may
be seen just above the line at the bottom of the gap h of the guide piece G ;
and this, although artificially produced, will be the true place of the real
horizon upon the horizon glass. The method of making the reflection of the
sun coincide, is the same as in other cases. The directions here given imply
that a coincidence is to be made as nearly as possible by the two lines thus
formed upon the two objects, the one being fixed and the other being capable of
moving upon its centre until the due effect is produced. But should it be
prefered, the coincidence may be formed with the lines on each side of the
gap h, in which case the guide G must be adjusted accordingly, so that a small
portion of the part d of the director E may be seen forming a minute black
line above each side of the cap h.
Fig. 10, K, represents a front view of a brass case, the sides of which are
made deep enough to cover the parts that form the artificial horizon, it is to
be fixed to the brass plate B by four screws that pass through the ears
0, 0, 0, 0. Fig. 11 represents a front view of the upper part of the same
case; the top and left-hand side are formed of plate glass, so that by this con-
trivance the whole of the parts may be completly covered from the effect of
high winds, and yet the parts necessary to been seen are quite visible. Fig. 12
represent a side view of Fig. 10, in order that the depth of the case may be
more plainly understood. The dotted line shew 'at p, p, p, in Fig. 1 is the
position upon which the case is screwed, the upper part is screwed to projecting
studs q, q. Fig. 13 represents the reverse side of a portion of Fig. 1; 'A, A,
shews a part of the ebony frame, which has the brass arc L screwed to it by
the screws r, r, r; the arc L is racked on its outer edge to receive the teeth of
the small pinion seen at s; the pinion s'is fixed upon the back part of the
index, but in this Figure the cock t is shewn only in dotted lines that the
position of the pinion may be more plainly seen. Fig. 14 represents a front
and side view of the cock t, which may be fixed to the index by two screws
that pass through the two small holes seen at the bottom of the front view.
The hole in which the axis of the pinion works is seen just above in the same
Figure. Figure 15 represents a milled-headed thumb screw, which is placed
upon the square part of the axis of the pinion s, and is retained there by the

page_text: binding nutt v. The peculiar advantage that ensues from this construction
and combination of the parts may be thus very shortly explained. When it is
desired to move the index at large by the hand, it may be done as the pinion
s is at liberty to turn freely upon its axis, and of course it will follow the
motion of the index whichever way it is moved, and as the teeth of the pinion
are constantly in gear with the teeth of the rack, it follows, that the instant a
minute adjustment is required there is no previous preparation of clamping
necessary, for the moment the finger and thumb are applied to the milled head,
the minute adjustment is then under the most perfect command of the observer,
and may be used with the greatest ease and precision. I shall here observe;
that as the radius of the arc that contains the divisions is much less in this
quadrant than in those in common use, I therefore prefer having it divided
into fourths of degrees, which will of course give half the number of divisions
that are usually produced upon the common sized arcs, hence it is necessary
that the nonius should also be reduced from 19 divisions to 9. But to this
part of the instrument I lay no claim, as this method of dividing the arc is
adopted merely to accommodate the reduced size of the arc. I shall here
observe that the small angular piece upon the upper part of the director E
should be cover'd with black varnish, and the part of the guide piece G, where
the
gap is made, should be either covered with any white substance, or it may
be made of any white metal, by which means the contrast will be the greatest.
And I hereby further declare that I do not claim as my Invention any of the
parts that are common to and have been used in quadrants before my Inven-
tion; and improvements consist entirely :-
First, in substituting a rack and pinion in lieu of the tangent screw, by
which means I am enabled to take an accurate observation with a quadrant
having such an appendage in less time, and consequently with greater certainty
than by any other means hitherto known or made use of.
Secondly, in constructing, combining, and applying certain parts herein set
forth and explained, and which I call a finder or director, and also a
part which I call a guide piece, by the use of which, in the manner and
way I have described, a more certain and effectual artificial horizon will be
obtained than was ever before known or made use of.
.
In witness whereof, I, the said Robert Benton Roxby, have hereunto
set my hand and seal, this Thirtieth day of September, in the year
of our Lord One thousand eight hundred and twenty-two.
R. B. (L.S.) ROXBY.

page_text: AND BE IT REMEMBERED, that on the Thirtieth day of September, in
the year of our Lord 1822, the aforesaid Robert Benton Roxby came before
our said Lord the King in His Chancery, and acknowledged the Specification
aforesaid, and all and every thing therein contained and specified, in form
above written. And also the Specification aforesaid was stamped according
to the tenor of the Statute made for that purpose.
Inrolled the Thirtieth day of September, in the year of our Lord Onie
thousand eight hundred and twenty-two.
Inrolled the Thirtieth day of September, in the year of our Lord One
thousand eight hundred and twenty-two.