IMPROVE- MENTS IN SHIPS' COMPASSES
Year: 1860

page_text: LETTERS PATENT to David Irons, of No. 31, Hamilton Street, Deptford,
in the County of Kent, Master Mariner, for the Invention of "IMPROVE-
MENTS IN SHIPS' COMPASSES."
Sealed the 14th August 1860, and dated the 17th February 1860.
PROVISIONAL SPECIFICATION left by tho said David Irons at the
Office of the Commissioners of Patents, with his Petition, on the 17th
February 1860.
I, DAVID IRONS, of No. 31, Hamilton Street, Deptford, in the County of
Kent, Master Mariner, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN SHIPS' COMPASSES," to be as follows:→
The objects of this Invention are to make ships' compasses more effective
and to act with more certainty than those of the ordinary construction, and to
prevent them being attracted by the iron of which ships are built or by the
metallic cargo in wooden ships.
I propose placing a dial or card (with the points of the compass marked
thereon) on a needle point let into a brass collar, said collar having four
branches with vertical needles at their ends upon which are placed four smaller
cards which term "satellites," the north of one of the small cards being near
to the south of the centre card, and the south of the opposite card being near
the north of the centre one, thus the magnets of all three cards will point to

page_text: north and repel each other, while the north of the third "satellite "is near the
west of the centre card, the south of the remaining one is near the east of the
centre.
The whole of the cards and branches are balanced on the same agate and
centre pin, and can be made either magnetic or true by the addition or
detaching of a magnet to run in an opposite direction on each card.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said David Irons in the Great Seal Patent Office on the
17th August 1860.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, DAVID
IRONS, of No. 31, Hamilton Street, Deptford, in the County of Kent, Master
Mariner, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Seventeenth day of February, in the year of our
Lord One thousand eight hundred and sixty, in the twenty-fourth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said David Irons, Her special licence that I, the said David Irons, my
executors, administrators, and assigns, or such others as I, the said David
Irons, my executors, administrators, and assigns, should at any time 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
SHIPS COMPASSES," upon the condition (amongst others) that I, the
said David Irons, my executors or administrators, by an instrument in
writing under my, or their, or one of their bands 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 David Irons, do hereby declare the
nature of my 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, that is to say:-
The objects of this Invention are to make ships' compasses more effective
and to act with more certainty than those of the ordinary construction, and to.
:

page_text: prevent them being attracted by the iron of which ships are built, or by the
metallic cargo in wooden ships.
In order to explain my said Invention as completely as possible, I now
proceed to describe the best means I am acquainted with for carrying the
same into practical effect, reference being had to the illustrative Sheets of
Drawings hereto annexed, and to the numeral figures and letters of reference
marked thereon respectively as follows:
DESCRIPTION OF THE DRAWINGS.
At Sheet 1, Fig. 1, is a view of the central steering card, having four
satellites placed around it, and forming by the arrangement of. magnets a
compass for the true meridian; Fig. 2 is another view of a similar description,
but having the magnets so arranged as to form a compass shewing the magnetic
north; Figs. 3 and 4 being a different arrangement of the satellites, answering
the same purposes as those before mentioned.
It will be seen that the four satellites move round the central steering card
resting on the one central stone, above which is screwed a cap having a spindle
or pivot its centre for the reception of the centre card; thus all the five cards
are moving as it were upon one centre, yet all independent of cach other.
At Fig. 1 the north and south magnets are in one piece, having short
magnets arranged one each side of every one, as shewn and indicated by the
letters, thus forming a true meridian compass; a similar description of compass
is exhibited at Fig. 3, with the exception that the satellites d, d, are crescents
and act on centres attached to the revolving frame, having small cross magnets
e, e, on each, and placed opposite to each other.
At Figs. 2 and 4, will be seen views of the magnetic bearing compasses,
similar in appearance to those before described, but having single magnets
only. In both cases six. or even eight satellites may be employed by
placing others between those shewn at Sheet 1 of the accompanying Drawings.
The satellites and central steering cards attending these compasses may be con-
structed either with small compass cards, crescent magnets, circular or semi-
circular magnets, revolving round the central steering card, as well as by
straight magnets forming the upper part of the letter T; cards may also be
constructed with triangular, tubular, and V-shaped needles, as well as with
straight needles, or both may be used, the hollow ones serving as a cover to the
straight.
At Sheet 2 will be seen various arrangements of magnets which I intend
using in combination with my satellites, Fig. 4, being intended for great circle

page_text: By the compass showing the true north at Sheet 1, a true course at sea can
always be steered, and correct angles measured on shore, by surveyors or
engineers to the true. meridian. The difference between the true north com-
pass and the magnetic bearing compass will show the amount of local attraction
on board iron vessels or wooden ships laden with iron, and the difference
between a compass as at present made and my true north will show the
variations of the compass where any exists.
Having now described the nature and object of my said Invention of
"Improvements in Ships' Compasses," and the manner in which the same
is to be performed, I would remark in conclusion that I do not confine or
restrict myself to the precise details herein mentioned and shewn in the
Drawing hereto annexed, as slight variations may be made therein without at all
departing from the principle of my Invention; but what I claim as my Inven-
tion intended to be secured to me by the herein in part recited Letters Patent
is forming ships' compasses with four or more satellites, all moving on the
same central stone, yet each having separate pivots, in the manner described
and shewn for the purposes herein set forth.
In witness whereof, I, the said David Irons, have hereunto set my
hand and seal, this Eighth day of August, in the year of our Lord
One thousand eight hundred and sixty.
Witness,
ALEX. PRINCE, Patent Agent,
4, Trafalgar Square,
Charing Cross.
D. IRONS. (L.S.)