AN IMPROVED LATITUDE INDICATOR
Year: 1884

page_text: I PHILIP MIDDLETON JUSTICE of 55 & 56 Chancery Lane in the County of
Middlesex Fellow of the Institute of Patent Agents do hereby declare the nature
of my Invention for "AN IMPROVED LATITUDE INDICATOR" to be as follows:-
This Invention relates to latitute indicators or instruments for determining the
latitude of any place on the earths surface at any day of the year by the sun at
noon, or at any night of the year at any hour by the North Polar Star in the
Northern Hemisphere or the South Polar Star in the Southern Hemisphere without
calculation. The object of my Invention is to furnish a means of determining the
latitude of any place on the earths surface where the person using my instrument
is, without calculation when the sun is visible at noon from the place the latitude
of which is desired to be obtained or when the North Polar Star or the South Polar
Star is visible. I accomplish this result by means of the latitude indicator which
may be described as follows. Upon the face of a metal disc is stamped or traced
a semicircle from the centre of the disc with a diameter from which centre is
erected a perpendicular, representing the equatorial line, this line divides the semi-
circle into two equal parts, with 90 degrees on either side which are designated by
lines representing degrees, half degrees, quarter degrees, and intermediates (the
diameter of the disc to be about two feet, or larger or smaller as desired). Between
the described semicircle and the margin of the plate, are three parallel arcs drawn
23 degrees 28 minutes on either side of the extended equatorial line representing
the position of the earth with the sun every day of the year. The space between-
the upper and lower of these arcs is divided on the right of the equatorial line
into 45 equal parts by straight lines traced from the upper to the lower arc, and
to the left of the equatorial line into 46 equal parts to represent the number of
days in the year, each half line representing two days; the upper and lower arcs
are divided into 12 parts representing the 12 months of the year; these twelve
divisions are designated by the prolongation of the lines marking the divisions in
the upper arc in a direction towards the circumference of the disc and in the lower
arc in a direction towards the centre of the semicircle, the ends of the arcs
representing the winter and summer solstice, each of the twelve divisions are
designated by the name of a month in the year, and the number of days in the:
[Price 6dı

page_text: month named. The divisions on the upper arc which is intersected by the
prolongation of the equatorial line being designated as September, next to the right,
October, next to the right November, the remaining number of straight lines to
the right at the end of the upper arc together with the requisite number on the
lower are being included under December, the next division to the left on the
lower are being designated as January, the next to the left as February, the next
to the left being designated as March, which is intersected by the equatorial line
the next to the left as April, the next as May, the next as June including lines
on the extreme left of the upper and lower arc, the next to the right in the upper
are as July, the next to the right as Augusty At the centre of the disc, passes
a small axle with a screw on which turns freely an indicator, a washer being placed
on the axle between the disc and the indicator; one extremity of the indicator
terminates in a pointer at or near the circumference of the circle, where the degrees
are marked, the other extremity, a short distance from the edge of the disc, to this
latter extremity, through a small hole in it is affixed by means of a short wire
or chain a weight as a plumb bob which serves to retain the indicator always in
a vertical position.
Upon the axle also turns freely a thin metal bar about 1/2 inch wide a washer
being placed between the indicator and the metal bar; the extremities of this bar
terminate near the edge of the disc, or a short distance beyond it; at the upper
extremity of this metal bar is affixed on the under side of it, just at the edge of
the disc, a small piece of metal of the same or somewhat narrower width than the
bar, and of a thickness corresponding to the distance between the disc and the bar
at the centre of the disc or at the axle, this small piece of metal serving as a
support or rest, between the disc and the bar. At the end of the bar which
extends beyond the edge of the disc, passes a screw, which at a short distance
passes through the end of a second metal bar of the saine width, and thickness
as the first which extends from the screw across the back of the disc, within a
short distance of the edge of the disc, being attached to the axle at the centre upon
A short
which it moves a washer being placed within the disc and the bar.
distance from the edge of the disc there is attached by means of a hinge, a small
metal bar extending beyond the edge of the disc to which is affixed a small thin
metal plate which is held in position when in use by a small spring at the edge
of the plate about one inch and a quarter in diameter in such a position that
when the small bar is parallel with the back of the disc, the plate will be at right
angles with the bar that crosses the face of the instrument. Upon the metal
bar passing across the face of the disc is affixed a metal tube the ends of which
terminate near the edge of the disc which is used for getting the line of the sun
and stars on the end of which tube is an
On a
eye piece with a sight hole.
continuation of the equatorial line is a small hole near the edge of the disc on
either side of which there are other small holes, these holes being large enough
to permit the passage of a hook by means of which the instrument is suspended.
The disc referred to in the above Specification should be preferably of metal.
The surface of the small plate should be dark coloured so as to show most
clearly the rays of the sun passing through the tube.
The method of using the instrument in ascertaining the latitude of a place at
noon when the sun is visible is a follows: Hold place or suspend the instrument
so that it will be in a vertical position, north and south with the face of the
instrument toward the west.
Move the metal bar over the face of the disc until a small pin marking the centre
of the side of the bar nearest the face of the disc is directly upon the day of the
month on which the instrument is being used, as indicated on the arc, then turn
the screw so that the bars are tightened to the disc then move the disc in
a line with the sun and until the rays of the sun fall directly through the tube,
and show upon the plate a circle of sunlight of the same diameter as the diameter
of the tube, the indicator will then point upon the face of the instrument to the
number of degrees, which number of degrees correctly represents the latitude of

page_text: the place where the person is who is using the instrument, the latitude being north
or south latitude accordingly as the indicator points the degrees above or below
the equatorial line.
The method of using the instrument in determining the latitude of a place at
any time of the night by the North Polar Star in the Northern Hemisphere, and
the South Polar Star in the Southern Hemisphere is as follows. Set the bar so
that the pin will be directly on the prescribed diameter, then turn the screw so
that the two bars are tightened on the disc, then let the observer look through
the tube, then move the instrument until the star is seen through the tube the
indicator will then point to the number of degrees marking the latitude north
or south of the equator of the place where the person making the observation is.
The principle upon which my instrument is constructed is as follows. The
latitude of a place is the distance north or south of the equator. By reason of
the inclination of the earths axis to the plane of its orbit, the sun has an
apparent motion, north of the equator. 23 degrees 28 minutes and south of the
equator 23 degrees 28 minutes during the course of the year as the dates of the
summer and winter solstice are known, as well as the dates of the vernal and
autumnal equinox, the number of degrees which the sun is, north or south of the
equator may be represented on the diagram by the arrangement above described
by a straight line drawn from the centre of a circle to the point in the arc,
representing the day of the month on which the latitude is sought to be obtained.
This line makes with the centre of the plane of the equator an angle which is
measured on the circumference of the semicircle. Now it is apparent, if the place,
the latitude of which is sought to be obtained is the same number of degrees
north or south of the equator, as the sun is on the day in question, that the angle
last referred to will measure the latitude of the place. Therefore to find the
latitude of any place which is north or south or in other words is nearer to or
farther from the equator at the time when it is desired to ascertain the latitude it
is evident that the angle made by the vertical line of the place with the centre of
the plane of the equator will be greater or less than the angle ascertained by the
line drawn from the centre of the semicircle as above referred to. This difference
between the angle of latitude and the angle of the suns position as represented by
the degrees can be ascertained by measuring on the meridian of the place, the
arc between the position of the sun on that meridian and the point of intersection
of the vertical line of the place with that meridian. This is ascertained by means
of my instrument which on being adjusted as specified in the above description
measures the difference of these angles by means of the indicator which is a
vertical line. The explanation of the working of my instrument in ascertaining
the latitude of a place when the North or South Polar Star is visible from
that place is as follows. The distance of the earth from these stars is so great
that to a person standing at the equator and looking at the star through the
tube of my instrument, he would be on a horizontal line with it and the
indicator would point to no degrees, but as he passed from the equator north or
south to look at the star through the tube (which is fixed parallel with the
diameter) it is necessary for him to place it at an angle which would be greater
or less in proportion to the distance that he is away from the equator, this distance
s measured by the arc described by the indicator as it moves from the equator
north or south.
Dated this Eighth day of Tanu 1001

page_text: I, PHILIP MIDDLETON JUSTICE of 55 & 56 Chancery Lane in the County of
Middlesex Fellow of the Institute of Patent Agents do hereby declare the nature
of said Invention for AN IMPROVED LATITUDE INDICATOR, and in what manner
the same is to be performed, to be particularly described and ascertained in and by
the following statement :-
This Invention relates to latitude indicators or instruments for determining the
latitude of any place on the earth's surface at any day of the year, by the sun at
noon, or at any night of the year, at any hour, by the North Polar Star in the
Northern Hemisphere, or the South Polar Star in the Southern Hemisphere without
calculation.
'
To clearly set out the nature of the Invention reference is made to the
accompanying Drawings which form part of this Specification.
The object of the Invention is to furnish a means of determining the latitude of
any place on the earth's surface where the person using the instrument is, without
calculation when the sun is visible at noon from the place, the latitude of which
is desired to be obtained or when the North Polar Star or the South Polar Star
is visible I accomplish this result by means of the "Latitude Indicator" the
instrument above referred to, illustrated in the accompanying Drawings in which
Fig. 1 is a front elevation of the instrument and ;-
Fig. 2 is a side elevation of the same.
Upon the face of the metal disc A. is stamped or traced a semicircle B. from the
centre of the disc with a diameter c, d, from which centre is erected a perpendicular
representing the equatorial line e. f. this line divides the semi-circle into two equal
parts with 90 degrees on either side which are designated by lines representing
degrees, half degrees quarter degrees and intermediates; the diameter of the
disc to be about two feet or larger or smaller as desired. Between the described
semi circle and the margin of the plate are three parallel arcs drawn 23 degrees and
28 minutes on either side of the extended equatorial line representing the position
of the earth with the sun every day of the year. The space between the upper
and lower of these arcs is divided on the right of the equatorial line into
45 equal parts by straight lines traced from the upper to the lower arc, and to
the left of the equatorial line e. f. into 46 equal parts to represent the number of
days in the year, each half line representing two days; the upper and lower arcs
are divided into 12 parts, representing the 12 months of the year; these twelve
divisions are designated by the prolongation of the lines marking the divisions in
the upper arc in a direction towards the circumference of the disc and in the lower
arc in a direction towards the centre of the semicircle, the ends of the ares
representing the winter and summer solstice, each of the twelve divisions are
designated by the name of a month in the year and the number of days in the
month nained. The division on the upper are which is intersected by the
prolongation of the equatorial line e, f, being designated as September, next to
the right, October next to the right November, the remaining number of straight
lines to the right at the end of the upper arc together with the requisite number
on the lower are being included under December, the next division to the left on
the lower are being designated as January, the next to the left as February the
next to the left being designated as March, which is intersected by the equatorial
line, the next to the left as April, the next as May, the next as June, including
lines on the extreme left of the upper and lower arc; the next to the right in the
upper arc as July, the next to the right as August. At the centre of the disc A.
.

page_text: passes a small axle with screw n. on which turns freely an indicator G, a washer m
being placed on the axle between the disc and the indicator; one extremity of the
indicator terminates in a pointer at or near the circumference of the circle where
the degrees are marked, the other extremity, a short distance from the edge of the
disc, to this latter extremity, through a small hole in it is affixed by means of a
short wire or chain a weight H as a plumb bob which serves to retain the indicator
always in a vertical position. Upon the axle n also. turns freely a thin metal
bar K about 1/2 inch wide a washer being placed between the indicator and the
metal bar; the extremities of this bar terminate near the edge of the disc, or a
short distance beyond it; at the upper extremity of this metal bar is affixed on the
under side of it, just at the edge of the disc, a small piece of metal of the same or
somewhat narrower width than the bar and of a thickness corresponding to the
distance between the disc and the bar; at the centre of the disc or at the axle,
this small piece of metal serving as a support or rest between the disc and the bar.
At the end of the bar K which extends beyond the edge of the disc passes a screw
which at a short distance passes through the end of a second metal bar t of the
same width and thickness as the first which extends from the screw across the
back of the disc, within a short distance of the edge of the disc being attached to
the axle at the centre upon which it moves, a washer being placed between the
disc and the bar. A short distance from the edge of the disc there is attached by
means of a hinge q a small metal bar extending beyond the edge of the disc to
which is affixed a small thin metal plate which is held in position when in use by
a small spring at the edge of the plate about one inch and a quarter in diameter, in
such a position that when the small bar is parallel with the back of the disc, the
plate S will be at right angles with the bar K that crosses the face of the
instrument; upon the metal bar K passing across the face of the disc is affixed
a metal tube i the ends of which terminate near the edge of the disc, which is used
for getting the line of the sun and stars; on the end of which tube is an eye piece
with a sight hole. On a continuation of the equatorial line e f. is a small hole near
the edge of the disc on either side of which there are other small holes, these holes
being large enough to permit the passage of a hook by means of which the
instrument is suspended. The disc a referred to in the above Specification should
be preferably of metal. The surface of the small plate S should be dark coloured
so as to show most clearly the rays of the sun passing through the tube. The
method of using the instrument in ascertaining the latitude of a place at noon
when the sun is visible is as follows.
Hold, place or suspend the instrument so that it will be in a vertical position,
north and south with the face of the instrument toward the west. Move the
metal bar K over the face of the disc a until a small pin u. marking the centre of
the side of the bar K nearest the face of the disc is directly upon the day of the
month on which the instrument is being used as indicated on the arcs x. y. z then
turn the screw so that the bars are tightened to the disc then move the disc in a
line with the sun and until the rays of the sun fall directly through the tube i and
show upon the plate S a circle of sunlight of the same diameter as the diameter of
the tube, the indicator g will then point upon the face of the instrument to the
number of degrees which number of degrees correctly represents the latitude of
the place where the person is who is using the instrument the latitude being north
or south latitude accordingly as the indicator points the degrees above or below the
equatorial line. The method of using the instrument in determining the latitude
of a place at any time of the night by the North Polar Star in the Northern
Hemisphere and the South Polar Star in the Southern Hemisphere is as follows
;-
Set the bar so that the pin will be directly on the prescribed diameter c. d. then
turn the screw so that the bars K and T are tightened on the disc then let the
observer look through the tube i. then move the instrument until the star is seen
through the tube the indicator will then point to the number of degrees marking
the latitude north or south of the equator of the place where the person making
the observation is.

page_text: The principle upon which the instrument is constructed is as follows. The
latitude of a place is the distance north or south of the equator. By reason of the
inclination of the earth's axis to the plane, of its orbit, the sun has an apparent
motion north of the equator 23 degrees 28 minutes and south of the equator
23 degrees 28 minutes during the course of the year as the dates of the summer
and winter solstice are known, as well as the dates of the vernal and autumnal
equinox the number of degrees which the sun is north or south of the equator may
be represented on the annexed diagram, by the arrangement above described by a
straight line drawn from the centre of a circle to the point in the arc x or y
representing the day of the month on which the latitude is sought to be obtained.
This line makes with the centre of the plane of the equator an angle which is
measured on the circumference of the semicircle a. Now it is apparent if the
place the latitude of which is sought to be obtained is the same number of degrees
north or south of the equator as the sun is on the day in question, that the angle
last referred to will measure the latitude of the place. Therefore to find the
latitude of any place which is north or south, or in other words is nearer to or
farther from the equator at the time when it is desired to ascertain the latitude it
is evident that the angle made by the vertical line of the place with the centre of
the plane of the equator will be greater or less than the angle ascertained by the
line drawn from the centre of the semicircle a as above referred to.
This difference between the angle of latitude and the angle of the sun's position
as represented by the degrees can be ascertained by measuring on the meridian of
the place the arc between the position of the sun on that meridian and the point of
intersection of the vertical line of the place with that meridian. This is
ascertained by means of this instrument which on being adjusted as specified in the
above description measures the difference of these angles by means of the indicator
which is a vertical line. The explanation of the working of the instrument in
ascertaining the latitude of a place when the North or South Polar Star is visible
from that place is as follows. The distance of the earth from these stars is so great
that to a person standing at the equator and looking at the star through the tube
of my instrument, he would be on a horizontal line with it and the indicator would
point to no degrees but as he passed from the equator north or south to look at the
star through the tube (which is fixed parallel with the diameter) it is necessary
for him to place it at an angle which would be greater or less in proportion to the
distance that he is away from the equator this distance is measured by the arc
described by the indicator as it moves from the equator north or south. I am not
aware that prior to this Invention there has been any instrument constructed,
designed or invented by which the latitude of a place may be ascertained by the
use of the means employed in the present instrument as more particularly set forth
in the above Specification. Having now particularly described and ascertained the
nature of my said Invention and in what manner the same is to be performed, I
declare that what I claim is -An improved latitude indicator consisting of a dise a.
on which is inscribed a semi-circle divided into 90° on each side of an equatorial
line also above said semi-circle divisions extending 23°. 28' on each side of said
equatorial line, said divisions representing the place of the sun during the days of
the year; bars K and t with cramp screw pointer g plumb h, tube i cross plate S
said bars, pointer and tube being suitably pivoted to said disc a. as shewn and
described.