An Improved Artificial Horizon.
Year: 1889

page_text: Date of Application, 16th May, 1889
Complete Specification Left, 12th Mar., 1890-Accepted, 12th Apr., 1890
An Improved Artificial Horizon.
1, HENRY ARTHUR GADSDEN of Saint George's Club Hanover Square in the-
County of Middlesex Gentleman do hereby declare the nature of this invention to be
s follows:-
This invention has reference to an improved artificial horizon for use with sextants
quadrants or otherwise for obtaining latitude and longitude or other purposes such as
measuring heights or distances.
According to this invention a rod arm or pin (hereinafter called a pin) projecting
from a suitably adjusted balanced beam is so arranged that it may be seen in front
of or behind the horizon glass of a sextant or quadrant or other similar instrument
so that it may serve in lieu of the natural horizon as base line for purposes such as
set forth.
The balance beam, which may be similar to a steel-yard, is provided with suitable
means for supporting and adjusting it and also for attaching it to the sextant or other
instrument with which it is to be used.
The pin to serve as the artificial horizon projects horizontally from and at right
angles to the beam and is arranged parallel to the axis about which the beam turns
in such wise that an observer when making observations with the sextant or other
instrument to which my instrument is applied, can see the pin in the line of sight.
In one arrangement the balance beam which may be of wire is so pivotted as to
have two unequal arms, the longer of which terminates in a part bent at a right angle
to serve as the pin; or instead of bending a part of the beam to a right angle a
separate wire or pin may be secured to the beam at a right angle. On the beam is a
screw for adjusting the point of connection with a pendulum hereinafter mentioned
for the purpose of altering the relative speed of rise and fall of the pin. The
pendulum is arranged below the beam and may itself be a beam pivotted midway of
its length and provided at its ends with weights; or instead of the end weights it
may have a pendent weight carried by a central arm.
The beam and the pendulum are connected by some suitable connection such as a
wire link or a hook in such a manner that the movement of the pendulum may
impart a more rapid movement to that end of the beam which carries the pin, this
movement being, by the adjusting screw carried by the beam made to correspond to
the movement of the sextant quadrant or other similar instrument to which my
apparatus is attached. To steady the pendulum, when a pendent weight is used the
arm or rod carrying it may be made to extend upward above its point of attachment
to the pendulum beam and be provided with a weight.
In connection with the pendulum and the arm or rod that carries the pendent
weight a screw may be provided for adjusting the position of the pendulum but if
the workmanship of the other parts be good this screw is not considered essential.
The mechanisin described for operating the pin can be enclosed in a box which
may be of light metal; and which will serve to support the beam and pendulum and
to protect them from the action of the wind or framework may be substituted for a
box. The instrument is made attachable to a sextant or quadrant or similar instru-
ment, preferably to the frame of the sight vane, in such a way as not to interfere
with the working parts of the instrument to which it is applied.
HENRY ARTHUR GADSDEN.

page_text: COMPLETE SPECIFICATION.
An Improved Artificial Horizon.
I, HENRY ARTHUR GADSDEN, of Saint George's Club, Hanover Square, in the
County of Middlesex, Gentleman, do hereby declare the nature of this invention
and in what manner the same is to be performed to be particularly described and
ascertained in and by the following 'statement:-
This invention has reference to an improved artificial horizon for use with sextants,
octants, quadrants or similar instruments used for obtaining altitudes of Celestial and
Terrestrial bodies, measuring distances &c.
According to this invention a rod arm or pin (hereinafter called a pin) projecting
from a suitably adjusted balanced beam is so arranged that it may be seen in front
of or behind the horizon glass of a sextant or other similar instrument so that it
may serve in lieu of the natural horizon as base line for purposes such as set forth.
The balance beam, which may be similar to a steel-yard, is provided with suitable
means for supporting and adjusting it and also for attaching it to the sextant or other
instrument with which it is to be used.
The pin to serve as the artificial horizon projects horizontally from and at right
angles to the beam and is arranged parallel to the axis about which the beam turns
in such wise that an observer when taking altitudes or observations with the sextant
or other instrument to which my instrument is applied, can see the pin in the line of
sight when the sextant or similar instrument is held vertical or nearly so.
In one arrangement the balance beam which may be of wire is so pivotted as to
have two unequal arms, the longer of which terminates in a part bent at a right
angle to serve as the pin; or instead of bending a part of the beam to a right angle
a separate wire or pin may be secured to the beam at a right angle. On the beam
may be a screw or any other well known appliance for adjusting the point of con-
nection with a pendulum hereinafter mentioned for the purpose of altering, the
relative speed of rise and full of the pin. The pendulum is preferably, for simplicity
and convenience, arranged below the beam and may itself be a beam pivotted midway
of its length, or its arms may be like a steel-yard of unequal length and provided
at the ends with balance weights; or instead of the end weights there may be a
pendant weight connected to the pendulum beam by a rod or arm. The balance
beam and the pendulum beam are connected by some suitable appliance such as a
wire link or a hook in such a manner that a given movement of the pendulum beam
may cause a greater and consequently quicker movement of that end of the balance
beam which carries the pin, such movement being, by the adjusting appliance carried
by the balance beam, made to accord with the fixed position of the natural horizon
however much or little the sextant or other similar instrument to which my
apparatus is attached is made to oscillate by the observer. To steady the pendulum
beam when a pendant weight is used a rod or arm may project upward from the
pendulum beam above its axis of oscillation and be provided with a weight, or any
well known or suitable appliance serving the same purpose may be used.
In connection with the pendulum beam and the rod or arm that carries the
pendant weight, a screw may be provided whereby the angle of the pendulum beam
in relation to the pendant rod or arm can be adjusted; or the pendant weight may
be made adjustable in any other convenient manner in relation to the pendulum
beam.
The mechanism described for operating the pin should be enclosed in a suitable
box so as to protect such mechanism from the action of the wind. The sides of the
box may be made to serve for supporting the balance beam and pendulum beam in
lien of providing frame work for that purpose; or the box may be simply a cover
or partial cover for the mechanism alone or for the mechanism and framework.
The instrument is made attachable to a sextant or other similar instrument
preferably to the frame of the sight vane or to the frame of the sextant nearest the

page_text: eye of the observer in such a way as not to interfere with the working parts of the
instrument to which it is attached.
In the accompanying drawings,
Fig. 1 illustrates in side elevation the general arrangement of an artificial horizon,
constructed according to this invention with box in section.
Fig. 2 is a plan, with the box cover removed.
1 is a balance beam of wire having two unequal arms, the end part 2 of the
longer of which is bent horizontally to a right angle and constitutes what is herein
referred to as the pin; it serves as the artificial horizon. The balance beam is
mounted to turn on a pin 3 carried by the sides of the box 4 which it is convenient
to make of unequal length (as shown in fig. 2) so as to leave an opening through
which the pin 2 can freely play. The box, which is open at the end adjacent to the
pin 2 serves to protect or partially protect the pin and the other parts of the apparatus
from the action of wind. The pin 2 is parallel to the axis about which the balance
beam turns. 5 is a pendulum beam, also of wire, mounted on a pin 6 carried
by the sides of the box. 7 is a wire link or hook connecting the balance beam
with the pendulum beam. 8 is an adjusting screw carried by the balance beam
for changing the position of the point of connexion of the link or hook 7, with
this beam relatively to the axis of oscillation of the beam 1 for the purpose
herein before mentioned. The pendulum beam may be provided at each end with a
weight 9; or in lieu of these end weights the pendulum beam may have connected
to it a pendulum rod or arm 10 furnished with a weight 11. In this case a steadying
device is or may be employed as shewn consisting of a rod or arm 10° with weight 12
above the pendulum beam. 13 is an adjusting screw whereby the angle of the
pendulum beam 5, in relation to the pendant arin 10 can be altered as desired for
adjusting the vertical position of the horizontal pin 2. The box can be provided
with a lug or with a clamping device of any suitable construction to enable it to be
attached to any particular sextant or other similar instrument with which it is
to be used. In the example, shown the box is for this purpose provided with
fastening screws 14.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is:
:-
1. A pin (rod or arm) in combination with means for supporting balancing and
adjusting it in front of or behind the horizon glass of a sextant, octant, quadrant, or
similar instrument in such a manner that the said pin is adapted to serve as a
substitute for or in lieu of the natural horizon.
2. The construction of an artificial horizon substantially as described and shewn.
HENRY A. GADSDEN.
W. Lloyd Wise,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.