Improvements in or connected with Sextants and other like Instruments.
Year: 1895

page_text: Date of Application, 24th. Apr., 1895
Complete Specification Left, 13th Aug., 1895-Accepted, 12th Oct., 1895
PROVISIONAL SPECIFICATION.
Improvements in or connected with Sextants and other like
Instruments.
I, SAMUEL MAXWELL WEST CROSKERY of 20 Highfield Crescent, Rock
Ferry, in the County of Chester, Master Mariner, do hereby declare the nature of
this invention to be as follows:-
This invention has reference to sextants, quadrants, and similar instruments, but
more especially to those instruments of this kind, which have been designed and
provided with what are called "artificial horizons" that is, means for obtaining an
artificial horizon when the sea horizon is not visible, the object of which is to enable
observations in taking the altitude of any object and more particularly celestial
objects, to be taken independently of the real horizon.
For convenience, this invention will be described as applied to an ordinary
sextant, it being understood, at the same time, that the means employed is equally
applicable to quadrants, and other analogous astronomical, and scientific instruments.
According to this invention, a means for indicating or obtaining an artificial'horizon
is adapted to be applied to the frame of the instrument, in any suitable way, in some
cases as an attachment. The means or device I employ is fixed in front of the
telescope, and comprises a pendulons device having on either side of the point about
which the device swings or moves, sights, which are adjustable; whilst the pendulum,
or part connected therewith, is enclosed within a case or box, and works in a
resisting medium, as oil, contained and held in said box. The pendulous device in
a simple form may consist of a pendulum below the point of support, upon the
upper part of which an arm or horn springs or extends on either side; and in the
extremities of which, the adjustable sights referred to, are held and fastened. In
one special form, the pendulous weight is made hollow at the lower end which dips
in the oil, say, castor oil, or glycerine, by this, better results are obtained, that
is, more steadiness is secured. The chamber or box in which the pendulum or
weight works is in one case not filled with liquid, that is the pendulum is only
partly immersed. This enables the instrument to be laid on its back, without the
oil spilling...
A suitable holding device, or stop, may be used in connection with the device,
by which it may be held stationary when not in use.
Beyond this device and line of sights, I provide a lamp which is so arranged
that while it illuminates the sights and enables them to be seen clearly on all
occasions at night, it does not dazzle or interfere with the time observations being
made. According to one arrangement and construction by which this effect is
obtained, the lamp glass is a coloured or darkened one, and the flame does not burn
directly behind it, but to one side of it within the case, the said glass being in line
with the clear part of the horizon glass and the sights.
This lamp is suitably supported by an arm or projection carried on the sighting
device and moves with it, and is provided with a shield above, by which the light
of the lamp is prevented from reacting or shining on the other glasses or parts of
the instrument.
In connection with instruments provided with these improvements, or similar
appliances, the telescope is removed and a simple tube or other simple sighting
device substituted, by which a greater range of vision laterally, is obtained; the
substitution of such a device for the telescope is made for the reason, that the

page_text: latter, I find, is objectionable, and does not afford the desired freedom and range in
cases when a vessel is pitching or rolling, and the platform is unsteady. A simple
method of obtaining this end consists in removing from existing telescope its
ordinary lenses and fittings, and simply using it as a tube, with a shaded.or coloured
glass sprung or slipped onto the end or moved in front of it.
In some cases I may use on the sight points, phosphoric or luminous paint and
in lieu of a lamp in that case, beyond or outside the device and line of sights,
black shield or surface or background is provided, to enable the use of the instrument
to be more effectual. This means of rendering visible the sights is more particularly
useful when using the instrument on very dark nights; while the use of a lamp as
aforesaid is useful under all circumstances and on all kinds of nights.
As regards the means of attachment of the device to the instrument, this may be
done by a thumb screw screwing into the frame of the instrument.
By the means herein described, navigation of vessels is assisted in foggy or hazy
weather when the sun is visible, but no horizon, with which to obtain an altitude;
for by its use the observer will be independent of the horizon. Further, at night,
when the horizon is seldom clear enough to enable an observation to obtain the
horizon to be made, the instrument will be very valuable, as by it, this is rendered
unnecessary. When the sights of the instrument. are once set as described, no
further action or adjustment at any time has to be made.
In some cases I provide in connection with the instrument, a stand on which the
instrument.is mounted. The connection between the instrument and the stand is
by a gimbal ring arrangement, and there is also carried by this gimbal ring
arrangement, a vessel in which oil or suitable liquid is contained, a weight with
fins or blades thereon, connected with the instrument support, being adapted to
work in the said oil or liquid. In one case, the said vessel is supported by a set of
gimbal rings carried by the case, while a second set supported from the vessel
carries the platform and frame on which the instrument is supported and the
pendulous weight. By this means, the instrument will remain steady even when
there is a very considerable rolling or pitching of the ship.
Liverpool. 23rd April 1895.
CHEESBROUGH & ROYSTON,
15 Water Street, Liverpool, Applicant's Patent Agents.
:
COME DEEM DI BUITICATION.
Improvements in or connected with Sextants and other like
Instruments.
1, SAMUEL MAXWELL WEST CROSKERY, of 20 Highfield Crescent, Rock
Ferry, in the County of Chester, Master Mariner, 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 sextants, quadrants, and similar instruments, but
more especially to those instruments of this kind, which have been designed and
provided with what are called "artificial horizons," that is, means for obtaining an
artificial horizon when the sea horizon is not visible, the object of which is to enable
observations in taking the altitude of any object, and more particularly celestial
objects, to be taken independently of the real horizon.
For convenience, this invention will be described as applied to an ordinary
sextant, it being understood, at the same time, that the means employed is
equally applicable to quadrants, and other analogous astronomical, and scientific
instruments.
According to this invention, a means for indicating or obtaining an artificial
horizon is adapted to be applied to the frame of the instrument, in any suitable

page_text: way, in some cases as an attachment. The means or device I employ is fixed ự
front of the telescope, and comprises a pendulous device having on either side of
the point about which the device swings or moves, sights. which are adjustable;
whilst the pendulum, or part connected therewith, is enclosed within. a case or box,
and works in a resisting medium; as oil, contained and held in said box. The
pendulous device in a simple form may consist of a pendulum below the point of
support, upon the upper part of which an arm or horn springs or extends on either
side; and in the extremities of which, the adjustable sights referred to, are held
and fastened. In one special form; the pendulous weight is made hollow at the lower
end which dips in the oil, say, castor oil or glycerine, by this, better results are
obtained, that is, more steadiness is secured. The chamber or box in which the
pendulum or weight works is in one case not filled with liquid, that is, the pendulum
is only partly immersed. This enables the instrument to be laid on its back, without
the oil spilling.
A suitable holding device, or stop, may be used in connection with the device, by
which it may be held stationary when not in use.
Beyond this device and line of sights, I provide a lamp which is so arranged
that, while it illuminates the sights and enables them to be seen clearly on all
occasions at night, it does not dazzle or interfere with the time observations being
made. According to one arrangement and construction by which this effect is
obtained, the lamp glass is a coloured or darkened one, and the flame does not burn
directly behind it, but on one side of it within the case, the said glass being in line
with the clear part of the horizon glass and the sights.
This lamp is suitably supported by an arm or projection carried ou the sighting
device and moves with it, and is provided with a shade above, by which the light of
the lamp is prevented from reacting or shining on the other glasses or parts of the
instrument.
In connection with instruments provided with these improvements, or similar
appliances, the telescope is removed and a simple tube or other simple sighting
device substituted, by which a greater range of vision laterally, is obtained; the
substitution of such a device for the telescope is made for the reason, that
the latter, I find, is objectionable, and does not afford the desired freedom
and range in cases when a vessel is pitching or rolling, and the platform is
unsteady. A simple method of obtaining this end consists in removing from
existing telescope its ordinary lenses and fittings, and simply using it as a tube,
with a shaded or coloured glass spring or slipped onto the end or moved in
front of it.
In some cases I may use on the sight points, phosphoric or luminous paint;
and in lieu of a lamp in that case, beyond or outside the device and line of sights,
a black shield or surface or background is provided to enable the use of the
instrument to be more effectual. This means of rendering visible the sights is
more particularly useful when using the instrument on very dark nights; while the
use of a lamp as aforesaid is useful under all circumstances and on all kinds
of nights.
As regards the means of attachment of the device to the instrument, this may be
done by a thumb screw screwing into the frame of the instrument.
By the means herein described, navigation of vessels is assisted in foggy or hazy
weather when the sun is visible, but no horizon, with which to obtain an altitude;
for by its use the observer will be independent of the horizon. Further, at night,
when the horizon is seldom clear enough to enable an observation to obtain the
horizon to be made, the instrument will be very valuable, as by it, this is rendered
unnecessary.
When the sights of the instrument are once set as described, no
further action or adjustment at any time has to be made.
In some cases I provide in connection with the instrument, a stand on which the
instrument is mounted. The connection between the instrument and the stand is
by a gimbal ring arrangement, and there is also carried by this gimbal ring arrange-
ment, a vessel in which oil or suitable liquid is contained, a weight with fins or

page_text: Diades thereon, connected with the instrument support, being adapted to work in
the, said oil or liquid. In one case, the said vessel is supported by a set of gimbal
rings carried by the case, while a second set supported from the vessel carries the
platform and frame on which the instrument is supported and the pendulous weight.
By this means, the instrument will remain steady even when there is a very
considerable rolling or pitching of the ship.
In the drawings illustrating this invention,
Figure 1 is a side elevation showing parts according to it, arranged in position on
a sextant frame..
:
Figure 2 shows a sectional elevation, and Figure 3 a cross section of the
pendulous sight device.
Figure 4 illustrates the front elevation of the lamp used in connection with the
invention; &
Figure 5 is an elevation, and Figure 6 a plan, illustrating the sight points and
lamp in detail.
Figure 7 is an elevation showing the stand above referred to with the instrument
thereon; whilst Figures 8 to 11 are elevations shewing details thereof.
Referring to the drawings, a represents generally an ordinary sextant frame with
the usual fittings of which is the horizon glass. In connection with this glass,
the pendulous sight device is arranged and used. This device consists of the arms o
and pendulous weight d and vessel e, the arms c & weight d being formed in one
and adapted to be mounted on a spindle to a part of the vessel e. On the ends of
the arms c, the sights c¹ and care mounted, c¹ being on one side of the horizon glass h,
and e² on the other side; and in connection with, and on the upper part of, this
arm, the small adjustable weight 3 is provided, by which, by sliding it in one
direction or the other, and fixing it in the position required, the adjustment aud
balance of the pendulous device is obtained. The pendulum & has, at the lower
part, projecting portions d', forming a space between them, and by these the
resistance of the oil (which is used in the vessel e to the level indicated by the
dotted lines) is increased, and the action of the device improved. The vessel e is
fastened to the frame a by a thumb screw, which presses the projecting lug el
against the side of the frame and secures the instrument to the sextant.
telescope through which the observations are made; and it consists of a simple
tubular device, provided preferably at the front end with a coloured glass, and at
the back end with an extending part . That is, the telescope is without lenses
and has merely in its front end the coloured glass. The telescope is secured to the
frame a in any suitable known way.
higa
is the lamp by which the points and are illuminated, this lamp is so
constructed that the full light of its fame does not sliine through the glass, and
upon the points. For rendering the points c¹ and e² visible by this lamp, the burner
portion is not opposite the window through which the light passes, that is to say,
it is at one side of it as shown, and the window is fitted with coloured glass and
shaded (different coloured glasses may be used); and, preferably, in addition to
this, further shading is used, as by inserting in front of the glass a piece of ordinary
blue paper such as blue correspondence paper. This, with the blue glass, will give
the strength or amount of light required, to enable the sights to be plainly seen.
The lamp i is mounted by an arin k fixed on the vessel e, and having on its end the
plate over the edges of which the lamp is slid by the turn in the edges of the
lamp at the back. A screw is provided in the arm k by which the lamp may be
raised up or lowered down and adjusted to the required height.
In action, when taking a sight, say at night, the sights c¹ and are rendered
visible by the illuminated glass or window, they being in the line of sight
between the telescope h and the lamp glass. When the star or object thrown or
reflected onto the mirror of the horizon glass is in line with the sights c and c²,
as seen through the telescope h, that position of the instrument and parts is the
correct one, and the angle can be read off the instrument in the usual way.
As to the behaviour of the pendulous device, as stated, by the end of the weight d

page_text: being in oil as described, the steadiness of the device is such that observations can
be made with the instrument with high accuracy.
The vessel e is provided internally with a ledge e² which will prevent the oil
coming out when the instrument is placed on its side temporarily, and a set screw³
is provided which when screwed up will prevent the device moving about and hold
it in position when not in use, as when stowed in its case.
As regards the modification above referred to, in which the sight tips or points.
are provided with phosphoric or luminous paint, this is illustrated in Figures 12
and 13. In these, the horizon glass b is shown in front elevation illustrating the point
in front of the mirror b', and the point behind it. When this is used, as stated, a
black shield or background (which may be the part on which the lamp slides) is.
used in lieu of the lamp i. This modification as stated is more particularly useful
when using the instrument on very dark nights.
With reference to Figures 7 to 11, the instrument is there shown mounted on :
stand. The stand consists of an outer box (in the lower part of which oil may be
used if desired), and an inner vessel m, having on its lower end a weight n, and
supported on by ordinary gimbal ring arrangement o, so that the vessel m retains
or tends to retain the true vertical position, when the box moves with the ship..
Within the vessel m, arms p are provided, on which the instrument and parts.
carrying and connected with it are supported. The carrying parts supported by
these arms consist of an outer gimbal ring p¹ supported by p, and an inner dise
supported on the gimbal ring pl. The instrument a is carried on this disc by a.
pin r, which is in the ring on which the instruinent a is supported; and from the
disc, a weights with fins s' is suspended by the rod p, the weight and fins being
adapted to work in the oil in the vessel m." The pin is secured in the socket o
the upper part of the disc q by the set screw . By so supporting the instrument
in the vessel m, and providing a balance weight in connection with its carrying
parts as described, and working in oil (or other suitable liquid) the instrument.
maintains a steady position in all weathers at sea.
In some cases introduce between the first sight c¹ and the horizon glass ba.
magnifying glass, by which the reflected star on the mirror thereof is magnified;.
by this the use of the instrument, and the taking of observations, is rendered
simpler.
Amongst other advantages the apparatus can be detached from the sextant and
can be adjusted and set correctly to the horizon on land and afterwards applied to.
the sextant or other instrument.
Having now particularly described and ascertained the nature of the said inven-.
tion I declare that what I claim is :-
1. In or for sextants or like instruments, a weighted pendulous device working
in oil (or other suitable liquid) contained in a vessel, and having arms and sights
on the end of such arms, disposed one on either side of the horizon glass, the said
device being adapted to operate and to be used substantially as herein set forth
and shown in the drawings hereto annexed.
2. In an artificial horizon arrangement for use in connection with sextants or
like instruments, having sights such as described, the employment of a lamp having
a dully illuminated window or glass forming a background to the sights, by which
they are rendered visible; substantially as herein set forth.
3. In a sextant or similar instrument with artificial horizon arrangement, the
combination of a pendulous sight device, a lamp forming an illuminated background
to said sights, and a telescope consisting mainly of simple tubular device as.
specified; arranged and operating substantially as and for the purposes described.
4. The employment in connection with sextants or similar instruments having
artificial horizon arrangements, of a stand, an internal vessel with loose supporting.
joints carried by said stard or suspended therefrom, and a gimbal or like arrange-
ment carried by said internal vessel and carrying the instrument, and provided with a

page_text: pendent weight; substantially as herein set forth with reference to Figures 7 to 11
of the drawings.
5. The different devices of or for artificial horizon arrangements for use on or in
connection with sextants or similar instruments, constructed and adapted to
operate particularly as set forth with reference to and shown in the different 5
figures of the drawings.
Dated this 12th day of August 1895.
CHEESBROUGH & ROYSTON,
15 Water Street, Liverpool, Applicant's Patent Agents.