IMPROVEMENTS IN MARINE AND SURVEYING COMPASSES
Year: 1855

page_text: LETTERS PATENT to James More, of Glasgow, in the County of Lanark,
North Britain, Rivet Manufacturer, for the Invention of "IMPROVEMENTS
IN MARINE AND SURVEYING COMPASSES."
PROVISIONAL SPECIFICATION left by the said James More at the Office
of the Commissioners of Patents, with his Petition, on the 30th August
1855.
I, JAMES MORE, of Glasgow, in the County of Lanark, North Britain,
Rivet Manufacturer, do hereby declare the nature of my said Invention of
"IMPROVEMENTS IN MARINE AND SURVEYING COMPASSES" to be as follows, that is
to say:-
This Invention relates to the prevention of the deranging influence of local
attraction upon the magnetic needles of marine and surveying compasses of
various kinds.
In the modification preferred for carrying out this Invention in practice, the
preventive treatment relates entirely to the magnetic needle. The needle is
coated or otherwise covered in and over on every part, with the exception of
the centre point of suspension, with pure shell-lac or gum shell-lac, or with
sealing-wax or other gum resin, or compositions wherein gum resins form a
part. The needle thus treated or coated is imbedded in cork of considerable
thickness or depth, and this cork covering is then finally coated with shell-lac
or gum resin, just as the needle itself was coated. In this condition the needle

page_text: is suspended and set to work in the usual way, when all or nearly all local attrac-
tion is negatived or prevented, & the accuracy of the needle's direction under
all or nearly all circumstances is fully secured. Instead of cork, the shell-lac
coated needle may be imbedded in the centre of a piece of elder tree, the pulp
of the tree or branch being left in to act as the protective surface immediately
in contact with the lac-coated needle. The pith or pulp of rushes and other
vegetables or plants may also be used for this secondary coating with good
results, but in all cases the secondary coating or vegetable envelope is treated
finally and externally with gum resin. The interior of the binnacle or compass
case may also be thus treated or coated for preventing the deranging influence
of local attraction.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said James More in the Great Seal Patent Office on the
29th February 1856.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
MORE, of Glasgow, in the County of Lanark, North Britain, Rivet Manu-
facturer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Thirtieth day of August, in the year of our Lord
One thousand eight hundred and fifty-five, in the nineteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said James More, Her special license that I, the said James More, my
executors, administrators, and assigns, or such others as I, the said James
More, my executors, administrators, or 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 MARINE
AND SURVEYING COMPASSES," upon the condition (amongst others) that I, the
said James More, by an instrument in writing under my hand and seal,
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 James More, 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

page_text: statement in writing, reference being had to the accompanying Drawings, and
to the letters and figures marked thereon, that is to say :-
My said Invention relates to the prevention of the deranging influence of
local attraction upon the magnetic needles of marine and surveying compasses
of various kinds.
In the modification preferred for carrying out this Invention in practice,
the preventive treatment relates entirely to the magnetic needle. The needle
is coated or otherwise covered in and over on every part, with the exception of
the centre point of suspension and the parts adjacent, with pure shell-lac or
gum shell-lac, or with sealing-wax or other gum resin, or compositions wherein
gum resins form a part. The needle thus treated or coated is imbedded in
cork of considerable thickness or depth, and this cork covering is then finally
coated with shell-lac or gum resin, just as the needle itself was coated. In this
condition the needle is suspended and set to work in the usual way, when all
or nearly all local attraction is negatived or prevented, and the accuracy of the
needle's direction under all or nearly all circumstances is fully secured. Instead
of cork, the shell-lac coated needle may be imbedded in the centre of a piece of
elder tree, the pulp of the tree or branch being left in to act as the protective
surface immediately in contact with the lac-coated needle.
The pith or pulp
of rushes and other vegetables or plants may also be used for this secondary
coating with good results, but in all cases the secondary coating or vegetable
envelope is treated finally and externally with gum resin. The interior of the
binnacle or compass case may also be thus treated or coated for preventing the
deranging influence of local attraction.
And in order that my said Invention may be properly understood, I have
hereunto appended and shall now proceed to describe a Sheet of explanatory
Drawings in illustration of one mode of working out my Invention in
practice.
Figure 1 on the Sheet of Drawings is a vertical section of a mariner's
compass as fitted with my improved protective coatings; Figure 2 is a plan of
the compass with one half of the card removed, and with the immediate
coating of the needle in horizontal section. The compass may be constructed,
as far as regards its general features, according to any of the various systems
in use, the one selected for representation in the present instance having a
cylindrical bowl or case A, made of brass, and closed by upper and lower glass
discs B. This bowl is suspended in a box C, by means of the usual arrange-
ment of gimbal ring D. The needle E is poised upon the stile F, being
furnished with an inverted conical cup G, which is made larger than usual to
prevent the needle from falling off the stile, in case it should be more liable to

page_text: do so from the increased weight and bulk given to it by my improved protective
coatings. The needle is coated with pure shell-lac or gum shell-lac, or with
sealing-wax or other gum resin, or composition containing gum resin, as
represented at H, such coating being applied to the surface of the needle in
any convenient manner, and being made to extend over a greater or less
portion of the needle's surface, as may be found most suitable in practice. In
addition to the resinous coating, each arm of the needle is inserted into a
species of casing I, of cork or other suitable material, such as vegetable pith or
fibre, such casing being of considerable thickness, although I do not confine
myself to any precise thickness, and being solid or partially hollow, as shewn
in the Drawings. In the present instance this casing is represented as
rectangular in transverse section, but I do not confine myself to any precise
form. The casing I of cork or other material is itself coated externally with a
resinous layer J, similar to that applied to the needle E, as already described
herein. As an additional protection to the needle, a lining or coating K, of
cork or other suitable vegetable substance, is applied to the inside of the
compass bowl A, and the surface of this lining K is itself furnished with a
resinous coating L. The protective coating K, L, may be applied to either
the inner or outer side of the bowl A, and a similar coating may also be
adapted to the box C, or in uny other way, for the purpose of protecting the
needle, provided that it is arranged so as to surround the latter. Two or more
such protective coatings may be used in combination, as represented in the
Drawings; or any one of them may be used singly, as may be found most
suitable and efficacious in practice. With the needle coated or imbedded in
this way, the compass is rendered capable of resisting the deranging influence
of local attraction to a very great extent, so that the navigator may place
much greater reliance upon such modified or prepared compasses than upon
the ordinary instrument.
Having now described and particularly ascertained the nature of my said
Invention, and the manner in which the same is or may be used or carried
into effect, I may observe, in conclusion, that I do not confine or restrict
myself to the precise details or arrangements which I have had occasion to
describe or refer to, as many variations may be made therefrom without
deviating from the principles or main features of my Invention; but what
I consider to be novel and original, and therefore claim as the Invention
secured to me by the herein-before in part recited Letters Patent, is,-
First, the general arrangement, construction, and application of protective
coatings or coverings for the needles in marine and other magnetic compasses,
as herein-before described.

page_text: Second, the application and use, in marine and other magnetic compasses,
of protective coatings of gum shell-lac, or other suitable resinous substance or
composition containing resin, such coatings being used alone or in combination
with casings, coatings, or linings of cork or other suitable vegetable material,
for the purpose of protecting the magnetic needle from the influence or
deranging action of local attraction, as herein-before described.
Third, the application and use of resinous matter combined or not with cork
or other suitable vegetable substance, or cork alone, as a lining or internal
coating for the compass case or bowl, or as an interposed medium to screen
the needle from external objects.
In witness whereof, I, the said James More, have hereunto set my
hand and seal, this Twenty-seventh day of February, One thousand
eight hundred and fifty-six.
JAMES MORE. (L.S.