IMPROVEMENTS IN APPARATUS FOR ASCERTAINING THE VARIATION OF SHIPS' COMPASSES FOR LOCAL ERRORS
Year: 1858

page_text: LETTERS PATENT to Robert Eardley Pinhey, of Woolstan, in the County
of Hampshire, and John Wood, of 58, High Street, Southampton, in the
Town and County of Southampton, Hampshire, for the Invention of
"IMPROVEMENTS IN APPARATUS FOR ASCERTAINING THE VARIATION OF SHIPS'
COMPASSES FOR LOCAL ERRORS."
Sealed the 15th March 1859, and dated the 5th November 1858.
PROVISIONAL SPECIFICATION left by the said Robert Eardley Pinhey
and John Wood at the Office of the Commissioners of Patents, with
their Petition, on the 5th November 1858.
We, ROBERT EARDLEY PINHEY, of Woolstan, in the County of Hampshire,
and John Wood, of 58, High Street, Southampton, in the Town and County
of Southampton, Hampshire, do hereby declare the nature of the Invention
for "IMPROVEMENTS IN APPARATUS POR ASCERTAINING THE VARIATION OF SHIPS'
COMPASSES FOR LOCAL ERRORS," to be as follows:-
This Invention has for its object improvements in apparatus for ascertaining
the variation of ships' compasses for local errors. For this purpose the bowl
containing the compass card and needle is arranged to fit into a ring of wood
or other suitable material which is mounted on gimbles. This ring has
jointed to it an instrument on the principle of a sun dial. This instrument we
construct in the form of a †, and the joint connecting it with the ring is
at its lower end; a time scale is graduated on the two sides of the stem of

page_text: the cross and also on the upper side of the two arms, and the shadow is cast
by one or other of the extremities of the two arms or by the upper end of the
stem, according to the time of day at which the observation is made. The
instrument is set by elevating the stem of the cross to an angle corresponding
with the complement of the latitude of the place by means of a scale marked
on the joint connecting the stem of the cross with the ring, and by then
turning the ring round until the shadow falls on to the scale, so as to mark
the local time of the place (as indicated by a watch correctly set by observation
or otherwise); when this is done, the stem of the cross points along the meridian
of the place, and a line formed on the ring in the same direction (called the
meridian line) then corresponds in direction with this meridian, and the anglo
between it and the line forming the north and south points of the compass is
the variation and local error of the compass.
For convenience of use the compass card is so arranged that it can be lifted
off its pivot to throw it out of action, and in order to maintain the ring in a
horizontal position, whatever be the elevation of the dial cross, counterpoise
weights are employed.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Robert Eardley Piuley and John Wood in the Great Seal
Patent Office on the 5th May 1859.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, ROBERT
EARDLEY PINHEY, of Woolstan, in the County of Hampshire, and JOHN WOOD,
of 58, High Street, Southampton, in the Town and County of Southampton,
Hampshire, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fifth day. of November, in the year of our Lord
One thousand eight hundred and fifty-eight, in the twenty-second year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto us,
the said Robert Eardley Pinhoy and John Wood, Her special licence that
we, the said Robert Eardley Pinhey and John Wood, our executors, adminis-
trators, and assigns, or such others as we, the said Robert Eardley Pinhey
and John Wood, our executors, administrators, and assigns, should at any
timè agree with, and no others, from time to time and at all times thereafter
during the term therein expressed, should and lawfully might make, use,
exercise, and vend, within the United Kingdom of Great Britain and Ireland,
the Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN

page_text: APPARATUS FOR ASCERTAINING THE VARIATION OF SHIPS' COMPASSES FOR LOCAL
ERRORS," upon the condition (amongst others) that we, the said Robert
Eardley Pinbey and John Wood, our executors or administrators, by an
instrument in writing under our or their hands and seals, or under the hand
and seal of one of us or them, should particularly describe and ascertain the
nature of the said Invention, and in what manner the same was to be per-
formed, 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 Robert Eardley Pinhey, on behalf of
myself and the said John Wood, do hereby declare the nature of the said
Invention, and in what manner the same is to be performed, to be par-
ticularly described and ascertained in and by the following statement thereof,
that is to say:-
This Invention has for its object improvements in apparatus for ascertaining
the variation of ships' compasses for local errors. For this purpose the bowl
containing the compass card and needle is arranged to fit into a ring of wood
or other suitable material which is mounted on gimbles. This ring has
jointed to it an instrument on the principle of a sun dial. This instrument we
construct in the form of a +, and the joint connecting it with the ring is at
its lower end; a time scale is graduated on the two sides of the stem of the
cross and also on the upper side of the two arms, and the shadow is cast by
one or other of the extremities of the two arms or by the upper end of the
stem, according to the time of day at which the observation is made. The
instrument is set by elevating the stem of the cross to an angle corresponding
with the complement of the latitude of the place by means of a scale marked
on the joint connecting the stem of the cross with the ring, and by then
turning the ring round until the shadow falls on to the scale so as to mark the
local time of the place (as indicated by a watch correctly set by observation
or otherwise); when this is done, the stem of the cross points along the meridian
of the place, and a line formed on the ring in the same direction (called the
meridian line) then corresponds in direction with this meridian, and the angle
between it and the line forming the north and south points of the compass is
the variation and local error of the compass.
For convenience of use the compass card is so arranged that it can be lifted
off its pivot to throw it out of action, and in order to maintain the ring in a
horizontal position, whatever be the elevation of the dial, cross counterpoise
weights are employed.
And in order that our said Invention may be most fully understood, and

page_text: Figure 1 is a side elevation, partly in section, and Figure 2 is a plan of
apparatus constructed according to our Invention. a, a, is the external box
or case of the apparatus; b is a brass ring mounted within the box a on axes
b, b and c is a bowl, mounted on a centre or pin c', which is carried by the
piece d mounted on axes at d', d', within the ring ; the bowl c contains a
compass card furnished with a magnetic needle or bar, and balanced on a
centre point in the usual manner; e is an instrument, made in the form of a t.
The graduations on one side of the stem of the cross are shewn in Figure 3,
those on the other side of the stem at Figure 4, and those on the upper side
of the two arms at Figure 1. In some cases we joint the instrumente to the
bowl c by the lower end of its stem at e', we find it, however, more convenient
to mount two standards f, f, on the bowl c, which, at their upper ends,. receive
studs or projections from the two arms of the cross, and the instrument c is
then capable of turning on these studs, so that it may be set to any inclination,
in the same manner as if it were jointed at e¹ to the bowl c. One of the
standards has fixed to it the graduated are g, by which the stem of the cross
or instrumente may be set to any desired inclination between the horizontal
and the vertical; h is a button, by depressing which, the compass card may
be lifted off its pivot; and i is the extremity of a rod, which, when drawn up,
stops the vibration of the bowl c by coming in contact with the weight c",
which balances it; j is a weight, forming a counterpoise to that of the instru-
ment e; is an indicator or pointer. The apparatus is employed in the
following manner:-It is first placed, so that the indicator or pointer & is in the
line of the ship's head, the stem of the cross or instrument e is then set at an
inclination to the horizon, equal to the complement of the latitude of the place
by means of the graduated are 7, and it is clamped in this position by the set
screw q, the bowl c and the parts connected with it are then turned round on
the centre or pin e', until the shadow, which the upper end of the stem of the
cross or instrument, or the extremity of either of its arms, (according to the
time of day when the observation is made) throws on the time scale, is brought
to coincide with the time at the place where the observation is taken, the
stem of the cross or instrument e is then in the direction of the meridian of
the place, that is to say, it points due north and south, and the angle which
this line makes with the north and south line of the compass of the apparatus,
or any other compass, is the variation and local error of the compass at the

page_text: time of the observation, and if from this the known variation be deducted, the
remainder is the local error. By means of the indicator or pointer k, which
turns down so as to approach the surface of the compass card, the angle
between the meridian line and the direction of the ship's head may be readily
read. It will be observed as a peculiarity of the apparatus above described, that
the arrangement of the instrument e is such, that the several parts of which it is
composed (videlicit, the stem and the two arms) each in turn acts as a style
to throw a shadow on to another of the parts, and that each of the several
parts also in turn serves as a time scale to receive the shadow.
Having thus described the nature of our Invention, and the manner of
performing the same, we would remark that we are aware that apparatus has
before been employed for ascertaining the variation of ships' compasses for
local errors, by causing the shadow from a style to fall on to a time scale
surrounding it; we do not therefore claim generally the ascertaining tho
variation of ships' compasses for local errors by means of a style and time
scale, but what we claim is, the constructing and arranging apparatus for this
purpose, as herein described.
In witness whereof, I, the said Robert Eardley Pinhey, have hereunto
set my hand and seal, this Second day of May, in the year of our
Lord One thousand eight hundred and fifty-nine.
Witness,
GEO. PITT.
ROBT. E. PINHEY. (L.S.)