IMPROVEMENTS IN NAUTICAL INSTRU- MENTS APPLICABLE FOR ASCERTAINING AND INDICATING THE TRUE SPHERICAL COURSE AND DISTANCE BETWEEN PORT AND PORT
Year: 1852

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, Jonn
MOORE, of Arthur's Town, in the County of Wexford, Ireland, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent, under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the First day of May,
One thousand eight hundred and fifty-two, in the fifteenth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
John Moore, my exors, adññiors, and assigns, Her especial licence, full power,
sole privilege and authority, that I, the said John Moore, my exors, admors,
and assigns, or such others as I, the said John Moore, my exors, admors, or
assigns, should at any time agree with, and no others, from time to time and
at all times during the term of years therein expressed, should and lawfully
might make, use, exercise, and vend, within England, Wales, and the Town
of Berwick-upon-Tweed, my Invention of "IMPROVEMENTS IN NAUTICAL INSTRU-
MENTS APPLICABLE FOR ASCERTAINING AND INDICATING THE TRUE SPHERICAL COURSE
AND DISTANCE BETWEEN PORT AND PORT;" in which said Letters Patent is con-
tained a proviso, that I, the said John Moore, shall cause a particular
description of the nature of my said Invention, and in what manner the same
is to be performed, by an instrument in writing under my hand and seal,
to be inrolled in Her Majesty's High Court of Chancery within six calendar
months next and immediately after the date of the said in part recited
Letters Patent, as in and by the same, reference being thereunto had, will
more fully and at large appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
John Moore, do hereby declare that the nature of my said Invention, and the
manner in which the same is to be performed, are fully described and ascer-
tained in and by the following statement thereof, reference being had to
the Drawings hereunto annexed, and to the figures and letters marked thereon,
that is to say-
My instruments consist of two graduated brass rings or meridians which are
so connected together that they may be set at any required angle to each
other by means of the divisions marked on a third ring placed equatorially to
the two meridian rings, and on which they slide. On the skeleton globe thus
constructed a fourth graduated brass ring can be clamped in any position,
being a great circle to the said globe.
And in order that my Invention may be most fully understood and readily
carried into effect, I will proceed to describe the Drawings.
DESCRIPTION OF THE DRAWINGS.
Figure 1 represents a side view of the apparatus as arranged for ascertaining
and indicating the true spherical course and distance between port and port.
A and B are the two meridian rings, the ring A, which is fixed on the foot, I call
the standing meridian, and the ring B the moveable meridian; they are shown
alone in Figures 2, 3, 4, and 5; Figure 2 showing a plan view of the ring A,
and Figure 3 a section through the poles; Figure 4, a plan of the ring B;
Figure 5, an edge view looking in a line with the poles. The sides of the
rings A and B, opposite to those shown in Figures 2 and 4, are not graduated,
but there is a small groove for a binding screw to enter, as is shown in Figure 3
at a; the section of the ring B is like that of the ring A, and it fits on to the
equatorial ring in the same manner as that ring, and as is shown in Figures 2
and 3; C, Figure 1, shows the equatorial ring, of which Figure 6 is a plan of
the side which is graduated to degrees, and Figure 7 is a section; D, Figure 1,
shows the great circle, which is clamped on to the meridian; it is shown in plan
in Figure 8, and an edge view is shown at Figure 9. It will be understood
that although the rings are shewn in the Drawing graduated only every ten
degrees, it will be necessary to graduate them in practice to the quarter of a
degree or finer; b, 61, and c, c¹, show the screws and nuts which connect
together the rings A and B in such a manner that they can move freely on
them as centres when the nuts are not screwed down on the ring B; d, d',
show two clamps, which clamp the meridian A to the equator C, when the
screws e, e, e', e¹, are screwed up; E and F are two dises of metal, which are
clamped on the standing meridian; they are shown alone at Figures 10, 11,

page_text: and 12, Figure 10 showing a plan view with the graduations; Figure 11 is a
vertical section, and Figure 12 is a view of the under side. The outer com-
pass f, shown in Figure 10, is fixed, but the inner one g is moveable round its
centre; h shows the screw which clamps the instrument on to the standing
meridian; it is turned by a key similar to a watch key; i, ¹, are two small
springs, which hold the instrument on to the meridian when the screw is not
screwed up; k is a hole in the centre, into which the screw pins 1, 7, of the
great circle D fall. The compass G, which is shown in Figures 13, 14, and
15, is similar to the other two, with the exception that in place of the hole k in
the centre there is placed a pivot in such a manner that it can turn freely on
its centre, and it is notched so as to fit and slide on the great circle; 1, ', are
the screw pins of the great circle; they are placed opposite to each other, and
can be turned by a key, so as to be caused to project more or less, as is
required; H is the foot, in which the instrument is fixed by means of the
binding screw H¹, which fastens it as in a vice, the jaws being lined with cork
or other yielding material; I is the arm carrying the clamp, which fixes the
great circle in any required position; it slides through the foot and is fastened
in any part of its course by the screw K. The double fork L slides in a hole
perpendicular to this arm, and is fastened by the screw M, and thus clamps
the ring in any required position.
I will now proceed to, describe the manner in which this instrument should
be used to find the angle of position or bearing, and also the arcal or true dis-
tance of any place from any other place. Set the standing meridian to the
longitude on the equator (either east or west) of one of the places, and clamp
it with the clamps d, d'. Fix by means of its screw one of the compasses with
the centre hole on this meridian at the latitude of the same place; fix on in the
same way the other compass (with the hole) at the antipodes on the opposite
meridian. Fix the compass with the pivot on one or other of the
moveable meridians, according as the longitude of the second place is
east or west, and at its latitude. Fix the same meridian at the longi-
tude of the second place on the equator and clamp by screwing up the
nuts at the poles; now place the great circle on the instrument, the pin
at 180° into the hole in the compass at the antipodes, its arc into the pivot of
the moveable compass, and screw its screw at 0 into the compass on the
standing meridian. The are between the compasses (representing the places)
will then show on the compasses the angles of position or bearing at either
place, both true and magnetic, the inner compasses being previously set to
differ from the outer ones by the amount of the variation, and the pivot in the
moveable compass will indicate on the great circle the arcal or true distancó

page_text: between the places. And now to find the line of course and the corresponding
latitudes and longitudes to be passed on transit between these two places, fix
the great circle by means of the clamp L; then loose the nuts c, c¹, at the
poles, and also the screw h of the moveable compass, which compass move
along the line of track, and it will show at each point in the track as the
moveable meridian changes its position the true and magnetic course the arcal
distance passed over and to be passed, also the latitude on the moveable
meridian, which meridian will indicate on the equator the corresponding
longitude to be passed at the same place.
I would remark that the moveable compass G should always be first set to
the place of departure, and the instrument will then show the true course
until the compasses come in contact, when the instrument must be reversed,
that is to say, the moveable compass must be set to the place of arrival,
and vice versa, by which means the track can be carried out.
Figure 16 shews a sectional view of the instrument as arranged for use in
the box which contains the ring N as shewn, representing the true horizon;
and Figure 17 shows a plan of the box and ring. It consists of the instru-
ment as before described, disconnected from the foot and without the great
circle; the other side of the equatorial ring is uppermost, and this side is
graduated to parts of twenty-four hours and minutes of time in the 'direction
of the movement of the hands of a watch, as is well understood, and also of
the semicircle or double quadrant O, which is shewn in plan at Figure 18
and a side view at Figure 19. The horizon ring has four screws m, m, m, m,
for adjustment, as shown in plan. The double quadrant has a screw pivot in
the centre of its are similar to those in the great circle D. The box contains
three adjustable metal slides or grooves n, n, n, inlaid with cork or similar
substance to hold the standing meridian at right angles to the horizon ring; in
the lower one a binding screw is placed to secure the standing meridian when
necessary. Figures 20 show a marker or pointer, which can be clamped on
to the rings at any required place.
I will now proceed to describe the means of using this instrument to find
the latitude, the amplitude, the azimuth, and, by consequence, the variation of
the compass, the time, and then, by consequence, the longitude. Set the
equatorial ring with XII. o'clk, coinciding with the standing and the opposite
meridian.
To find the latitude by meridian altitude.-Elevate the pole to the supposed
latitude; place a compass (with a hole in it) on the standing meridian loosely;
place the double quadrant with its pivot in the hole of the compass, bring the
altitude observed marked on the quadrant, with one of the pointers to coincide

page_text: with the reduced declination, marked by a pointer on the standing meridian,
then will the latitude be indicated by the compass at the zenith, or the pole
will be elevated to the amount of the latitude on the opposite meridian.
To find the latitude by double altitude.-Proceed by placing the instrument
as before, having first marked the quadrant with the two observed altitudes;
place the moveable meridian to the equator at the time noted of the first
observation, bring the two observed altitudes (marked on the quadrant,) in
succession, to coincide with the reduced declination (marked on the moveable
meridian); when the moveable meridian is moved to the amount of the elapsed
time between the two observations, and when all have been brought to coin-
cide by movement of the instrument, the result will be indicated as in the
first case.
Note. The following must be attended to as regards both the above pro-
blems. If the altitude be north and declination north the latitude will be
south (the elevated pole coinciding), and vice versa (unless the observer be
between the sun or other body and equator, in which case the result is op-
posite,) but if the altitude be north and declination south, or vice versa, the
elevated pole and latitude will coincide with the name of the declination.
To find the amplitude and time corresponding.-Elevate the polo to the
known latitude on the opposite meridian. The declination on the moveable
meridian, if brought to the horizon, will cut it at the degree of amplitude
from north or south of the same name as the declination, and the apparent
time corresponding will be shewn on the equator by the inside line or indicator
of the same moveable meridian.
To find the azimuth time and variation of the compass.-Elevate the pole
as above, place the compass on the zenith, also the quadrant on the compass,
on the quadrant mark the altitude and bring it to coincide with the reduced
declination on the moveable meridian; its lower points or legs will cut the
horizon at the degree of azimuth from the north or south, the moveable
meridian showing on the equator the apparent time, to which apply the
equation, and the result will give the difference of longitude in time, if
Greenwich mean time be noted when the altitude was taken. Bring the mag-
netic bearings by the inner compass (if observed also when the altitude was
taken) under the line of arc of the quadrant as placed, the difference
between the inner and outer compasses will be the magnetic variation by
azimuth compass.
Having thus described the nature of my said Invention and the manner of
performing the same, I would have it understood that I do not confine myself
to the several details herein described, so long as the peculiar character of my

page_text: Invention be retained, as variations may be made without departing from my
Invention. But what I claim is the mode herein described of combining
parts into instruments applicable in resolving nautical problems as herein
explained.
In witness whereof, I, the said John Moore, have hereunto set my
hand and seal, this First day of November, in the year of our Lord
One thousand eight hundred and fifty-two.
Enrolled the First day of November, in the year of our Lord One
thousand eight hundred and fifty-two.