IMPROVEMENTS IN QUADRANTS, Sxx- 'TANTS, OR OTHER OTHER SIMILAR INSTRUMENTS TO WHICH ARTIFICIAL HORIZONS ARE APPLICABLE
Year: 1860

page_text: LETTERS PATENT to James Rahill, of Ramsgate, in the County of Kent,
Gentleman, for the Invention of "IMPROVEMENTS IN QUADRANTS, Sxx-
'TANTS, OR OTHER
OTHER SIMILAR INSTRUMENTS TO WHICH ARTIFICIAL HORIZONS
ARE APPLICABLE."
Sealed the 20th November 1860, and dated the 30th July 1860.
PROVISIONAL SPECIFICATION left by the said James Rahill at the
Office of the Commissioners of Patents, with his Petition, on
the 30th July 1860.
I, JAMES RAHILL, of Ramsgate, in the County of Kent, Gentleman, do
hereby declare the nature of the Invention for "IMPROVEMENTS IN QUADRANTS.
SEXTANTS. OR OTHER SIMILAR INSTRUMENTS TO WHICH ARTIFICIAL HORIZONS ARE
APPLICABLE," to be as follows.:-
..
This Invention has for its object improvements in the arrangement and
construction of artificial horizons suitable for being applied to quadrants,
sextants, or other similar instruments for measuring altitudes or angles, by
which the altitude of the sun or other heavenly body may be ascertained
when the true horizon is obscured.
My improvements consist in employing a pendulum connected to a hori-
zontal bar, to the ends of which are attached two thin bars or arms standing
at right angles to the pendulum, by preference one on each side of the horizon
glass; and 1 prefer to place the axis of motion of the pendulum about the
[Price 8d.]

page_text: centre of the horizon glass in a line with the centre of the tube or eye-
piece through which the observation is taken; the said two bars or arms
when properly adjusted to the true horizontal plane forming a true and
reliable horizon for measuring altitudes or angles, as is well understood,
and the horizontal arms or bars may be readily adjusted with the true
horizon from time to time to ascertain the correctness of the instrument by
means of a moveable weight attached to the pendulum, and capable of
adjustment by means of a screw or otherwise.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said James Rahill in the Great Seal Patent Office on the 30th
January 1861.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
RAHILL, of Ramsgate, in the County of Kent, Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Thirtieth day of July, in the year of our Lord
One thousand eight hundred and sixty, in the twenty-fourth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
James Rahill, Her special licence that I, the said James Rahill, my
executors, administrators, and assigns, or such others as I, the said James
Rahill, 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 QUADRANTS,
SEXTANTS, OR OTHER SIMILAR INSTRUMENTS TO WHICH ARTIFICIAL HORIZONS ARE
APPLICABLE," upon the condition (amongst others) that I, the said James
Rahill, 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 James Rahill,do hereby declare the
nature of the said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement thereof, that is to say :-

page_text: This Invention has for its object improvements in the arrangement and
construction of artificial horizons suitable for being applied to quadrants,
sextants, or other similar instruments for measuring altitudes or angles, by
which the altitude of the sun or other heavenly body may be ascertained
when the true horizon is obscured.
5.
My improvements consist in employing pendulum connected to a hori-
zontal bar, to the end of which are attached two thin bars or arms standing
at right angles to the pendulum (by preference one on each side of the
horizon glass); and I prefer to place the axis of motion of the pendulum
about the centre of the horizon glass in a line with the centre of the tube
or eye-piece through which the observation is taken; the said two bars or
arms when properly adjusted to the true horizontal plane forming a true
and reliable horizon for measuring altitudes or angles, as is well under-
stood, and the horizontal arms or bars may be readily adjusted with the true
horizon from time to ti ne to ascertain the correctness of the instrument by
means of a moveable weight attached to the pendulum, and capable of
adjustment by means of a screw or otherwise.
And in order that my Invention may be most fully understood and readily
practised, I will proceed to describe the Drawing hereunto annexed.
DESCRIPTION OF THE DRAWING.
Figure 1 shews a side view; and Figure 2 a plan of a sextant, having
my improvements applied thereto; Figure 3 shows a side view.; Figure 4, a
plan; and Figure 5, an end view of the pendulous apparatus separately; the
other Figures shew some of the parts separately.
a is a pendulum, suspended on a pin joint or axis at a¹, carried by the
support 6, which is capable of sliding up and down in the vertical guide b¹,
forming part of the plate or bar 62, which is fixed by a screw 6³, or in any
other couvenient manner to the frame of the horizon glass, or to any other
suitable part of the sextant or other similar instrument for measuringaltitudes
or angles; c is a screw, fixed in the forked piece or support ; the screw c
passes up through a hole in the end of the plate 62; and c¹ is a screw collar;
and a screw nut on the screw c, by which the height of the pendulum may
be correctly adjusted and secured so as to place the two thin bars or arms
a³, as, fixed at right angles to the horizontal bar a² of the pendulum in a
correct line with the centre of the horizon glass; a is a moveable weight,
which is capable of moving to and fro horizontally on the screw a³, carried by
the bearings a fixed on the lower end of the pendulum a, by which means the
horizontal position of the bars a³, a³, may be correctly adjusted. It will be

page_text: seen on examining the Drawing that the axis of motion at of the pendulum a
is placed so as to be in a line, or nearly. so, with the centre of the horizon
glass and of the tube or eye-piece d, through which the observation is taken;
and although I prefer this arrangement I do not intend to confine myself
thereto, as other arrangements of the parts may be adopted without departing
from my Invention, and it will be easily, understood by persons acquainted
with the use of instruments of the above description how to adjust the
horizontal arms or bars a³, a³, with the true horizon from time to time, as
opportunities offer, and thus ascertain the correctness of the instrument for
taking observations when the true horizon is obscured.
Having thus described the nature of my Invention, and the manner of
performing the same, I would have it understood that I do not claim the
application of a pendulum or artificial horizon to quadrants, sextants, or other
similar instruments for measuring altitudes, angles, &c., other arrangements
of pendulous apparatus.forming artificial horizons having been before applied
thereto; but what I claim is the arrangement and adaptation to instruments
of the above description of a pendulum having one or more horizontal bars
or-arms, and capable of adjustment with the true horizon and the centre of
the horizon glass and cye-piece, such bars or arms forming an artificial
horizon, which may be relied upon for taking observations when the true
horizon is obscured, as herein described.
In witness whereof, I, the said James Rahill, have hereunto set my
hand and seal, this 29th day of January, in the year of our Lord
One thousand eight hundred and sixty-one.
Witness,
G. H. BIRKBECK,
34, Southampton Buildings,
Chancery Lane.
JAMES RAHILL. (L.B.)