IMPROVE- MENTS IN THE METHOD OF AND APPARATUS FOR DETERMINING GEOGRAPHICALLY THE SITUATION OF VESSELS AT SEA
Year: 1882

page_text: LETTERS PATENT to Philip Middleton Justice of 14 Southampton Buildings
in the County of Middlesex Patent Agent for an invention of "IMPROVE-
MENTS IN THE METHOD OF AND APPARATUS FOR DETERMINING GEOGRAPHICALLY
THE SITUATION OF VESSELS AT SEA A communication from abroad by Juan
PROVISIONAL SPECIFICATION left by the said Philip Middleton Justice
at the Office of the Commissioners of Patents on the 24th May 1882.
PHILIP MIDDLETON JUSTICE of 14 Southampton Buildings in the County of
Middlesex Patent Agent IMPROVEMENTS IN THE METHOD OF AND APPARATUS FOR
DETERMINING GEOGRAPHICALLY THE SITUATION OF VESSELS AT SEA a communi-
cation from abroad by Juan Justo Oginaga temporarily of the City of Madrid in
the Kingdom of Spain
"
This invention relates to the method and apparatus employed for determining
geographically the position of a vessel when. at sea by means of two observations
taken of suitable heavenly bodies, which observations are subsequently utilized
and by means of an adjustable globe or sphere provided with suitable graduated
bars or strips representing the meridian and equator and an illumination quadrant
together with the requisite verniers, the geographical position of the vessel is
determined The invention consists of the method and apparatus hereinafter
described by which the desired end may be attained The problem is simply
reduced to the tracing of two arches of parallels of illumination, the centres of
which are the geographical points which at the moment of the observation of the
altitudes, have the observed bodies in the zenith and which I call "poles of illumi-
nation" the radii of the same being the zenithal distances of the observed celestial
bodies and the situation of the vessel being the point of intersection of both
curves
To find the situation of a ship by this method it is necessary to take two
observations in different verticals duly noting the chronometer's hour, such

page_text: °
observations may be made of the Sun at different hours or of any other luminous
heavenly body or the observations may be made simultaneously of the Sun and
Moon or any other body. If the observations are not made simultaneously and
should the vessel have changed its situation in the intervening space of time in a
direction which may not be perpendicular to the bearings of the observed body,
in order to determine the situation corresponding to the second altitude it will be
necessary to reduce the first altitude to what it would have been if taken at the
same spot as the second and this may be accomplished in the following manner
The angle formed by the vessel between the direction of the keel and the vertical
of the first observed body will be taken as the course (deducting it from 180 degrees
if obtuse) and the navigated distance as the distance, the difference of latitude will
be found by the table for working the dead reckonings which will be the
correction (distance x cosine of angle) and this will be added to the first altitude
if the angle has been acute or deducted if it has been obtuse, to reduce it to what
it would have been if observed from the same spot as that at which the second
observation is taken For the purpose of working the problem which is exceedingly
simple, by my graphical method I have invented a special form of sphere or globe
representing the earth The said sphere or globe may be of any convenient
diameter that is to say from twentyfive centimeters up If made of 1 meter
146 diameter each centimeter would correspond to one degree The globe is
provided with a vernier for latitudes, a vernier for longitudes a vernier for altitudes,
a graduated meridian, an equator, an illumination quadrant, a pencil for tracing
the arcs of the parallels of illumination set screws for pressure and vernier of
-latitude, a micrometric worm or toothed wheel and tangent points where the sphere
or globe rests The lines representing the meridian, and equator are graduated
and are provided with the verniers by which the miles and fractions of the same
may be appreciated The sphere has also an arch of 90 degrees which will be
called the "illumination quadrant" and in the zero of its vernier the pointed
pencil is fixed which through the quadrant as an axis is connected to the zero of
the vernier which is used to adjust the latitudes In this vernier the minutes will
be counted either on the right or on the left of zero so that it may be used for
both the northern and the southern latitudes
In the like manner the second vernier is made to count the eastern and the
western longitudes
The equatorial rack or the analagous arch is provided with the toothed wheel or
micrometric worm which may be easily connected and disconnected so that the
sphere is allowed to rotate easily when disconnected it being fixed when the
longitude has been accurately fixed The poles of illumination of the sun, moon or
..stars, the altitudes of which have been observed are located in latitudes according
to the declinations which are given in the nautical almanacks and in corresponding
longitudes to their horary angles, therefore if the Sun is the body observed its
western longitude is equal to the true astronomical hours of the first meridian
given by the chronometer its error and the equation of time being considered;
should any other body be the observed one it will be equal to the difference of its
right ascension with the right ascension or sidereal time of the first meridian (that
is to say meantime of the first meridian + sidereal time) to be found by means of
the chronometer
When the sphere has been brought to its required position and fixed the
longitude of the pole of illumination of one of the altitudes taken is made to
coincide or meet the metallic meridian by means of the second vernier ; the first
vernier of the meridian being fixed in its corresponding latitude and the pencil
being secured to the vernier of the illumination quadrant according to the true
altitude, part of a curve is traced with the resulting radius towards the sea so far
at least as the spot in which the ship is supposed to be and in this way the first
arch of the parallel of illumination will have been traced
By repeating the operation in respect to the other altitude taken and tracing
the second arch of the parallel of illumination in such a manner that it passes over

page_text: the first, the point at which they intersect will be that of the situation of the
vessel The sphere can be employed with equal advantages for the graphical
determination of the latitudes by ex-meridian altitudes, longitudes by chronometers
or any other analagous problems and likewise for the courses and distances by
great circle sailing also for azimuths by the hour or altitudes with a view of
determining the deviation of compasses the latter being a great source of anxiety
to persons in charge of iron and steel vessels
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Philip Middleton Justice in the Great Seal Patent Office on the
11th November 1882.
"
PHILIP MIDDLETON JUSTICE of 14 Southampton Buildings in the County of
Middlesex Patent Agent "IMPROVEMENTS IN THE METHOD OF AND APPARATUS
FOR DETERMINING GEOGRAPHICALLY THE SITUATION OF VESSELS AT SEA
A com-
munication from abroad by Juan Justo Oginaga temporarily of the City of Madrid
in the Kingdom of Spain
This Invention relates to the method and apparatus employed for determining
geographically the position of a vessel when at sea by means of two observations
taken of suitable heavenly bodies, which observations are subsequently utilized
and by means of an adjustable globe or sphere provided with suitable graduated
bars or strips representing the meridian and equator and an illumination quadrant
together with the requisite verniers, the geographical position of the vessel is
determined The invention consists of the method and apparatus hereinafter
described by which the desired end may be attained.
The problem is simply reduced to the tracing of two arches of parallels of
illumination, the centres of which are the geographical points which at the
moment of the observation of the altitudes, have the observed bodies in the zenith,
and which I call "poles of illumination" the radii of the same being the zenithal
distances of the observed celestial bodies, and the situation of the vessel being the
point of intersection of both curves To find the situation of a ship by this method,
it is necessary to take two observations in different verticals duly noting the
chronometer's hour; such observations may be made of the Sun at different hours,
or of any other luminous heavenly body, or the observations may be made
simultaneously of the Sun and moon or any other body If the observations are
not made simultaneously and should the vessel have changed its situation in the
intervening space of time in a direction which may not be perpendicular to the
bearings of the observed body, in order to determine the situation corresponding to
the second altitude, it will be necessary to reduce the first altitude to what it
would have have been if taken at the same spot as the second and this may be
accomplished in the following manner The angle formed by the vessel between

page_text: the direction of the keel and the vertical of the first observed body will be taken
as the course (deducting it from 180 degrees if obtuse) and the navigated distance,
as the distance, the difference of latitude will be found by the table for working
the dead reckonings which will be the correction (distance x cosine of angle) and
this will be added to the first altitude if the angle has been acute, or deducted if
it has been obtuse, to reduce it to what it would have been if observed from the
same spot as that at which the second observation is taken For the purpose of
working the problem which is exceedingly simple, by my graphical method I have
invented a special form of sphere or globe representing the earth and which is
shown in the accompanying drawing which forms part of this specification The
said sphere or globe may be of any convenient diameter that is to say from twenty-
five centimeters up If made of 1 meter, 146 diameter each centimeter would
correspond to one degree In the drawing represents the vernier for latitudes;
2 the vernier for longitudes; 3 the vernier for altitudes; A A the graduated
meridian; B B the equator; CC the illumination quadrant a, a, the first arc of
the parallel of illumination, a¹ a¹ the second are of the parallel of illumination;
L the pencil for tracing the said arcs of the parallels of illumination; S the position
of the vessel; X X the set screws for pressure and vernier of latitude; 0 0 the
equatorial rack; P the micrometric worm or toothed wheel and U. U. U the
tangent points where the sphere or globe rests
The lines representing the meridian A. A and equator BB are graduated and
are provided with verniers 1, 2 by which the miles and fractions of the same may
be appreciated The sphere has also an arch of 90 degrees C. C which will be
called the "illumination quadrant" and in the zero of the vernier 3, a pointed
pencil L is fixed, which through the quadrant C C an axis is connected to the
zero of the vernier 1 which is used to adjust the latitudes In this vernier the
minutes will be counted either on the right or on the left of zero so that it may be
used for both the northern and the southern latitudes In the like manner the
vernier 2 is made to count the eastern and the western longitudes The equatorial
rack O. O or the analogous arch is provided with a toothed wheel or micrometric
worm P which may be easily connected and disconnected so that the sphere is
allowed to rotate easily when disconnected, it being fixed when the longitude has
been accurately fixed The poles of illumination of the Sun, Moon, or Stars, the
altitudes of which have been observed are located in latitudes according to the
declinations which are given in the nautical almanacks and in corresponding
longitudes to their horary angles, therefore if the Sun is the body observed its
western longitude is equal to the true astronomical hours of the first meridian
given by the chronometer, its error and the equation of time being considered;
should any other body be the observed one it will be equal to the difference
of its right ascension with the right ascension or sidereal time of the first meridian
(that is to say meantime of the first meridian + sidereal time) to be found by
means of the chronometer When the sphere has been brought to its required
position and fixed, the longitude of the pole of illumination of one of the altitudes
taken is made to coincide or meet the metallic meridian A. A. A by means of the
vernier 2;
the vernier 1 of the meridian being fixed in its corresponding latitude,
and the pencil L being secured to the vernier 3 of the illumination quadrant
according to the true altitude, a part of a curve is traced with the resulting radius
towards the sea, so far at least as the spot in which the ship is supposed to be,
and in this way the first arch of the parallel of illumination will have been traced
By repeating the operation in respect to the other altitude taking and tracing the
second arch of the parallel of illumination in such a manner that it passes over the
first, the point at which they intersect will be that of the situation of the vessel
It is evident that such point will be the more exact as the angle formed by the
two arches is nearer to 90 degrees which will be easily ascertained in order to
know the best times for observations or to select the celestial bodies considering
only that the verticals being radii of those curves they deflect from them a
quadrant or 90 degrees of azimuth, it being therefore sufficient to notice that the

page_text: azimuthal difference of 90 degrees will be the most convenient as it will produce
equal angles at the intersection of both curves For practical purposes of
navigation it will be a sufficient approximation if the result from the observations
of altitudes give an azimuthal difference which is not under 45 degrees or
above 135
The before described method is based on the theory that, all stars independent
of the effects of parallax and refraction are visible in one of the hemispheres and
invisible in the other The line which limits these hemispheres, is a great circle,
which I call the great circle of illumination The plane of this passes by the centre
of the earth and is normal to the axis passing from the centre of the body to that
of the earth; and it is clear that it being the limits of illumination and shadow
the star is seen at O degree of altitude owing to its horizon being parallel to the
said axis. At 90 degrees of the maximum of illumination towards the star, is the
pole of the system which I call pole of illumination the horizon of which is normal
to the before mentioned axis, this coincides with the vertical line and therefore the
star is seen at 90 degrees of altitude exactly on the zenith The inhabitants of the
illuminated hemisphere will see therefore the body at a greater or smaller altitude
according as they find themselves nearer to or farther from the pole of illumination
By the rotary movement of the earth all the stars continually change their poles
of illumination apparently passing by earth parallels which are equal to their
declinations which are given by the nautical almanacks, and the longitudes of
which are easily found by means of the chronometer Its true astronomical hours
(corrected from error and equation of time) are equal to the westerly horary and
similar also to the westerly longitudes by which the poles of illumination pass
successively if the Sun is the luminous body observed For the stars the difference
of their right ascension compared to the right ascension or sidereal hours of the
first meridian; obtained by means of the chronometer will give the westerly
longitudes of the geographical point of the pole of illumination according to
the progressive variation and to that corresponding to the instant at which the
observation takes place
Therefore if nautical almanacks give the declination of the star equal to the
parallel or latitude of the pole of illumination and if by means of the chronometer
the longitude can be ascertained these two co-ordinates will determine the
geographical point on which depends the system of the parallels of illumination
concentric to it On the other hand the altitudes observed are complements of the
distances to the said point or centre of the common system and by any of them
the radius of the curve of the parallel of illumination is known and the tracing of
this curve must give the circumference, at one point of which the vessel must be
It is clear that by another similar observation made on the conditions of another
system of parallels of illumination we shall have another pole of illumination or
centre and a new radius of tracing for another parallel of illumination at one point
of which the vessel must also be and since the vessel must be at the same time on
the two curves or parallels of illumination it must be at that point at which the
curves intersect one another Although by the prolongation of the two parallels of
illumination belonging to the different poles, luminous bodies observed in different
verticals, two intersections will result, the one so far from the point near which
the vessel is known to be that it is not considered in the solution of the problem
As has been already stated, the verticals being radii of the said curves or parallels
of illumination they deflect a quadrant froin them, it is sufficient therefore to
observe that the azimuthal difference of 90 degrees will be the most convenient
since it will produce the intersection at right angles as complementary to the
azimuth, determining with the greatest precision the situation of the vessel, at
least with sufficient approximation for general navigation purposes The sphere
can be employed with equal advantages for the graphical determination of the
latitudes by ex-meridian altitudes, longitudes by chronometers or any other
analagous problem and likewise for the courses and distances by great circle
sailing, also for azimuths by the hour or altitudes with a view of determining the

page_text: deviation of compasses, the latter being a great source of anxiety to persons in
charge of iron and steel vessels To clearly explain the advantages of this invention
I will compare it with that of Summer with which it has a certain amount of
analogy; Summer's method requires four calculations of chronometrical longitudes
before proceeding to trace the projections, and although lately by the use of
azimuthal tables, the calculations of the problem have been reduced to one half of
the primitive work required by calculating only two chronometrical longitudes and
then tracing the projections perpendicular to the azimuths there is still an
inconvenient amount of mathematical work to be done with logarithmical tables
and with the corresponding arithmetical operations, in which operations, errors are
too likely to occur These inconveniences are obviated by the use of my invention
Summer's projections being the result of four chronometrical longitudes which were
merely cords of the true arches and the projections of the two chronometrical
longitudes and perpendicular to the azimuths being only tangents to the same both
systems of projections are liable to error, when the intersection which fixes the
determining point is produced by the cords of the first instance or when the
tangents in the second case are at a distant point from the base line Neither of
these defects occur when this invention is employed and the sphere is constructed
with accuracy With a good sphere the situation of vessels at sea can be ascertained
with the greatest ease and without the risk of such frequent mistakes as are likely
to occur in the complicated use of logarithms Having described the invention of
my foreign correspondent and how the same may be employed by persons skilled
in the art to which it apertains What I claim and desire to secure by Letters
Patent is
1st The arrangement of parts hereinbefore described forming the apparatus for
determing the position of a vessel at sea, consisting of a properly divided
globe or sphere provided with an equatorial rack O O, graduated meridian A. A
illumination quadrant C C and verniers 1, 2 and 3 all operating substantially
as and for the purposes set forth
2nd In an apparatus for determining the position of a vessel at sea consisting of
a globe or sphere provided with graduated meridian equatorial rack and
illumination quadrant, the wheels U U, pressure screws X and equatorial
screw P, all operating substantially as and for the purposes set forth.
In Witness whereof I the said Philip Middleton Justice have hereunto set my
hand and seal this Eleventh day of November in the year of Our Lord one
thousand eight hundred and eighty two.
igned, sealed and delivered
in the presence of
HENRY BHATCHWELL
53 Chancery Lane.
W.C
PHILIP M. JUSTICE
(L.S.)