IMPROVEMENTS IN NAUTICAL AND SURVEYING INSTRUMENTS FOR MEASURING ANGLES
Year: 1859

page_text: LETTERS PATENT to George Gowland, of Liverpool, in the County of
Lancashire, Chronometer and Nautical Instrument Maker, for the
Invention of "IMPROVEMENTS IN NAUTICAL AND SURVEYING INSTRUMENTS
FOR MEASURING ANGLES."
Sealed the 6th March 1860, and dated the 8th September 1859.
PROVISIONAL SPECIFICATION left by the said George Gowland at the
Office of the Commissioners of Patents, with his Petition, on the
8th September 1859.
1, GEORGE GOWLAND, of Liverpool, in the County of Lancashire, Chro-
nometer and Nautical Instrument Maker, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN NAUTICAL AND SURVEYING INSTRUMENTS
FOR MEASURING ANGLES," to be as follows:-
This Invention has for its object improvements in nautical and surveying
instruments, such as sextants, quadrants, theodolites, and other similar instru-
ments (to which artificial horizons are applicable) for taking observations,
measuring angles. Heretofore when artificial horizons have been employed,
having a pendulum and indicator combined therewith, and applied to instru-
ments of the above description for taking observations independent of true
horizon, owing to the motion of vessels at sea, and from other causes, the
action of such pendulum apparatus has been found so unsteady and uncertain

page_text: as to render them practically useless. Now, my improvements consist in
rendering the action of the pendulous apparatus and indicator employed in
connexion with artificial horizons steady and uniform, so as to be in a great
measure uninfluenced by the motion of the ship or vessel on which the observa-
tion is being taken. For this purpose I prefer to employ a horse-shoe or other
suitably shaped magnet, suspended on an axis or axes in a closed box or case
mounted on the sextant or other instrument for measuring angles, such box or
case being filled with water, spirit, oil, mercury, or other fluid of greater
density than the atmosphere, by which the sudden movement of the suspended
magnet will be resisted for a short interval during any temporary change in
the position of the measuring instrument occasioned by the motion of the
vessel, or from other causes. Exterior of the case before described, I suspend
in a chamber open to the atmosphere another but much lighter magnet, the
axis on which it moves being concentric or nearly so with the axis of the
magnet suspended in the fluid. The poles of the two magnets are so arranged,
that any movement of the larger magnet will control or impart a a similar
movement to the lighter one. On the axis of the lighter magnet there is a
cranked arm, on which a small vertical disc is mounted having a notch on its
upper edge; when the instrument is adjusted, the disc will be retained in a
vertical position, and when the edge of the disc, on looking through the sight
glass or telescope attached to the instrument, appears in visual contact with a
horizontal line drawn across a transparent tube or chamber placed over the
magnets, the instrument will then show the correct horizon, the transparent
tube being placed in a correct line with the sight glass or telescope.
In place
of horse-shoe magnets I employ them of circular form, and suspend the larger
one in fluid contained in a circular chamber having an opening in its centre,
in which the lighter magnet with its cranked arm and vertical disc is
suspended; this transparent opening in the chamber having the horizontal
line drawn across it, and adjusted with the edge of the vertical disc, as before
described. The case or vessel containing the magnet suspended in fluid should
in all cases be formed with a small reservoir above, to avoid having any space
containing air. When taking observations at night, and in obscure weather,
I ignite a small jet placed at the back of the transparent chamber (containing
the disc and horizontal line); this jet may be supplied with oil or spirit from
the chamber containing the magnet. Or, in place of employing magnets, as
before described, a simple bar or rod having a flat surface thereon suspended
in a closed chamber or vessel containing a fluid, and having an arm and disc,
or indicator, adjustable with a horizontal line across a transparent tube or
chamber, as before described, may be employed, my Invention having for its

page_text: object the use of a more dense medium than the atmosphere for a suspended
paddle or surface to move in, when used in connection with instruments for
measuring angles at sea or on land.
Another of my improvements in instruments of the above description for
measuring angles consists in the application of binocular in place of the single
telescope glasses heretofore used with such instruments.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said George Gowland in the Great Seal Patent Office on the
8th March 1860.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
GOWLAND, of Liverpool, in the County of Lancashire, Chronometer and
Nautical Instrument Maker, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eighth day of September, in the year of our Lord
One thousand eight hundred and fifty-nine, in the twenty-third year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said George Gowland, Her special licence that I, the said George Gowland,
my executors, administrators, and assigns, or such others as I, the said
George Gowland, my executors, administrators, and assigns, should at any
time agree with, and no others, from time to time, and at all times there-
after during the term therein expressed, should and lawfully might make, use
exercise, and vend, within the United Kingdom of Great Britain and Ire-
land, the Channel Islands, and Isle of Man, an Invention for "IMPROVE-
MENTS IN NAUTICAL AND SURVEYING INSTRUMENTS FOR MEASURING ANGLES," upon
the condition (amongst others) that I, the said George Gowland, 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 George Gowland, 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 :-
This Invention has for its object improvements in nautical and surveying

page_text: instruments, such as sextants, quadrants, theodolites, and other similar instru-
ments (to which artificial horizons are applicable) for taking observations,
measuring angles and altitudes. Heretofore, when artificial horizons have
been employed having a pendulum and indicator combined therewith and
applied to instruments of the above description for taking observations inde-
pendent of the true horizon, owing to the motion of vessels at sea, and from
other causes, the action of such pendulum apparatus has been found so
unsteady and uncertain as to render them practically useless.
Now, my improvements consist in rendering the action of the pendulous
apparatus and indicator employed in connection with artificial horizons steady
and uniform, so as to be in a great measure uninfluenced by the motion of the
ship or vessel on which the observation is being taken. For this purpose I
prefer to employ a horse-shoe or other suitably shaped magnet suspended on
an axis or axes in a closed box or case mounted on the sextant or other
instrument for measuring angles, such box or case being filled with water,
spirit, oil, mercury, or other fluid of greater density than the atmosphere by
which the sudden movement of the suspended magnet will be resisted for a
short interval during any temporary change in the position of the measuring
instrument occasioned by the motion of the vessel, or from other causes.
Exterior of the case before described I suspend in a chamber open to the
atmosphere another but much lighter magnet, the axis on which it moves being
concentric or nearly so with the axis of the magnet suspended in the fluid.
The poles of the two magnets are so arranged that any movement of the larger
magnet will control or impart a similar movement to the lighter one. On the
axis of the lighter magnet there is a cranked arm on which a small vertical
disc is mounted, having a notch on its upper edge. When the instrument is
adjusted the disc will be retained in a vertical position, and when the edge of
the disc, on looking through the sight glass or telescope attached to the instru-
ment, appears in visual contact with a horizontal line drawn across a trans-
parent tube or chamber placed over the magnets, the instrument will then
shew the correct horizon, the transparent tube being placed in a correct line
with the sight glass or telescope. In place of horse-shoe magnets I employ
them of circular form, and suspend the larger one in fluid contained in a
circular chamber having an opening in its centre in which the lighter magnet
with its cranked arm and vertical disc is suspended, this transparent opening
in the chamber having the horizontal line drawn across it, and adjusted
with the edge of the vertical disc, as before described. The case or vessel
containing the magnet, suspended in fluid, should in all cases be formed with a
small reservoir above to avoid having any space containing air. When taking

page_text: observations at night, and in obscure weather, I ignite a small jet placed at
the back of the transparent chamber (containing the disc and horizontal line);
this jet may be supplied with oil or spirit from the chamber containing the
magnet. Or, in place of employing magnets, as before described, a simple bar
or rod having a flat surface thereon suspended in a closed chamber or vessel
containing a fluid, and having an arm and disc or indicator adjustable with a
horizontal line across a transparent tube or chamber, as before described, may
be employed, my Invention having for its object the use of a more dense
medium than the atmosphere for a suspended paddle or surface to move in
when used in connection with instruments for measuring angles at sea or
on land.
Another of my improvements in instruments of the above description for
measuring angles consists in the application of binocular in place of the single
telescope glasses heretofore used with such instruments.
And in order that my Invention may be most fully understood and
readily practiced, I will proceed to describe the Drawings hereunto annexed.
DESCRIPTION OF THE DRAWINGS.
Figure 1 shows the outline of a sextant having pendulous indicating appa-
ratus A applied thereto, suitably arranged for indicating the true horizon.
according to the first part of my Invention; Figures 2 and 3 show two vertical
sections, and Figures 4 and 5 a side view and plan of the pendulous indicating
apparatus A, separate or disconnected from the sextant or other instrument for
taking observations, mensuring angles and altitudes. The pendulous indi-
cating apparatus is mounted on the sextant, as shown at A, Figure 1, with the
upper part opposite to or in a line with the horizon glass B, and eye-piece or
object glass C, which are of the ordinary description. The apparatus A is
carried by an arm fixed to the sextant, and is capable of being attached and
detached when desired. a is a closed box, case, or vessel, divided into three
compartments, as shown, in the centre one a¹ of which an ordinary horse-shoe
magnetis suspended on axes 6'; the compartment a¹ is filled with water,
spirit, oil, mercury, or other fluid of greater density than the atmosphere, in
order to retard the sudden oscillations of the suspended magnet b, which is at
all times submerged in the fluid, and there is a small chamber or reservoir a*
above the magnet b and chamber a', which serves to prevent the small quantity
or bubble of air contained in the closed vessel a' from influencing the move-
ment of the magnet 6 submerged in the fluid, and it is the means of preventing
the simultaneous movement of the fluid in which a magnet or other pendulous
apparatus is suspended with the movement of such pendulous apparatus which
b

page_text: constitutes an important feature in my Invention; and I mention this in order
that it may be distinctly understood that I make no claim to the partial sus-
pension of a pendulum in mercury or other fluid in connection with indicating
apparatus for the purpose of arranging artificial horizons, as I am aware that
the lower end of a pendulum has before been suspended in a vessel partially
filled with or containing mercury or other fluid for this purpose, but owing to
the simultaneous or nearly simultaneous movement of the mercury or other
fluid with the pendulum, little, if any advantage, was derived from such arrange-
ments of indicating apparatus. Exterior of the closed chamber a', another, but
-much lighter magnet c, is suspended, the two poles of which descend into the
side compartments a², a², of the chamber a, which are open to the atmosphere,
and the poles of the two magnets b and c are arranged so that the south pole
of one magnet is placed opposite or near to the north pole of the other in order
that the more powerful magnet b may control or impart its movement to the
lighter magnet c, the two magnets moving simultaneously as though they were
one magnet. To the upper part of the magnet c a cranked arm c¹ is attached,
which passes up into the transparent tube or chamber d, which is placed.in a
perfectly horizontal line with the sight or object glass of the sextant or other
instrument for taking observations or measuring angles. The arm c¹ carries
a small disc or indicator c³, the upper edge of which has a small notch cut in
it, and when the sextant or other similar instrument for measuring angles or
altitudes is held so that the upper edge of the disc or indicator c is on a level,
and appears in visual contact with a line drawn or fixed across the centre of
the transparent tube or chamber d, the instrument will be in a correct position
for taking the desired observations, altitude, or angle, as the case may be.
Figure 6 shows part of a sextant having another arrangement of pendu-
lous indicating apparatus A applied thereto according to this part of my
Invention; Figures 7 and 8 are vertical sections; and Figures 9 and 10 a
side view and plan of this arrangement of pendulous indicating apparatus
separated from the sextant or other instrument for measuring altitudes,
angles, &c. This arrangement of apparatus A simply differs from the
arrangement previously described in the shape of the magnet b, which is of a
circular form, and is suspended in a circular chamber a' filled with water or
other fluid, as before described. The chamber a' surrounds the transparent
tube or chamber d, in which the indicating disc or instrument c is suspended,
which is made of soft iron, and is consequently controlled in its movement by
the movement of the magnet b. The chamber or vessel a¹ is furnished with
a tube or reservoir a* above the magnet b, to contain the bubble of air, as
before described. a² is a tube or pipe which conducts oil or spirit from the

page_text: chamber a¹ to supply the wick tube a³ of the lamp ƒ placed at the back of the
transparent chamber, which jet may be lighted at night or in obscure weather,
or the lamp may be supplied with oil or spirit from a separate vessel.
Figure 11 shows the outline of a sextant baving another arrangement of
pendulous indicating apparatus A applied thereto constructed according to
this part of my Invention; Figures 12 and 13 shew vertical sections;
and Figures 14 and 15, a side view and plan of the apparatus A separate or
detached from the sextant. In this arrangement of pendulous and indicating
apparatus, the use of a magnet or magnets is dispensed with, and a simple
bar or rod of suitable from is suspended in a transparent tube or chamber
containing fluid, the indicating disc or instrument being carried by and forming
part of the suspended paddle or oscillating surface; a is a circular, or it might
be any other suitably shaped fluid-tight chamber, having two of its opposite sides
fitted or formed with glass or other transparent surfaces, across one of which
the artificial horizon line is drawn ; the upper part of the chamber a is furnished
with a small chamber or reservoir a*, as described in respect to the previous
arrangements; & is a circular bar or instrument suspended on an axis or axes
in the chamber a so as to oscillate therein, and on the bar or instrument b
a paddle or surface is fixed to aid, by the resistance offered by the fluid, in.
retarding the sudden oscillation of the suspended bar or instrument 6 and
indicator c; c is the disc or indicating instrument which is carried by an arm
fixed to the lower part of the suspended bar or instrument b. The transparent
chamber a containing the pendulous indicating apparatus is mounted on the
sextant, as shewn, or in any other convenient manner, in a correct horizontal
line with the sight glass or telescope indicated by dotted lines in Figure 11.
I would remark that, although I have for convenience shown the pendulous
indicating apparatus in each arrangement as applied to a sextant, it is not
essential that this should be so, as the apparatus is equally applicable to other
instruments with which artificial horizons are employed for taking observa-
tions, measuring altitudes and angles.
I will now describe the second part of my improvements in instruments of
the above description, which consists in the application of binocular in place
of the single telescope glasses heretofore used with such instruments.
Figure 16 shews a side view, and Figure 17 a plan, of a sextant (or it
might be any other similar instrument for measuring angles where sight
tubes or telescopes are used in connexion therewith) having binocular glasses
adapted thereto according to this part of my Invention. The binocular sight
glasses a are carried by an arm a', and may when required be readily attached
to or detached from the sextant or other similar instrument for measuring

page_text: angles by means of the screw a³ or by other convenient means; and the use of
binocular glasses with sextants or other similar instruments for measuring
angles is suitable either when taking observations by means of the true
horizon, or with such instruments when artificial horizons are employed; but
when artificial horizons are employed, it is of importance that the artificial
horizon line should be drawn across or placed as near to the horizon glass as
possible, and the disc or indicator employed should be mounted as near as
possible to the same, so as to be at the same focus or nearly so with the
horizon glass.
Having thus described the nature of my Invention and the manner of
carrying the same into practice, I would have it understood that I do not
confine myself to the exact details herein described, so long as the peculiar
character of my Invention be retained, but what I claim is,-
First, the application to nautical and surveying instruments for measuring
angles of pendulous apparatus suspended in a chamber, so as at all times to
be completely submerged in a fluid more dense than the atmosphere, to give
steadiness thereto, such apparatus being combined with an instrument to indi-
cate the true horizon as described in respect to Figures 1, 2, 3, 4, 5, 6, 7, 8,
10, 11, 12, 13, 14, and 15 of the Drawings.
Secondly, I claim the application of binocular in place of single tube tele-
scope glasses to nautical and surveying instruments as herein described.
In witness whereof, I, the said George Gowland, have hereunto set
my hand and seal, this Fifth day of March, in the year of our Lord
One thousand eight hundred and sixty.
Witness,
J. G. TONGUE.
G. GOWLAND. (L.S.)