IMPROVE- MENTS IN THE CONSTRUCTION OF LIQUID COMPASSES
Year: 1866

page_text: LETTERS PATENT to Alexander Cairns, of Liverpool, in the County of
Lancaster, Nautical Instrument Maker, for the Invention of "IMPROVE-
MENTS IN THE CONSTRUCTION OF LIQUID COMPASSES."
Sealed the 8th March 1867, and dated the 14th September 1866.
PROVISIONAL SPECIFICATION left by the said Alexander Cairns at the
Office of the Commissioners of Patents, with his Petition, on the 14th
September 1866.
I, ALEXANDER CAIRNS, of Liverpool, in the County of Lancaster, Nautical
Instrument Maker, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN THE CONSTRUCTION OF LIQUID COMPASSES," to be as
follows:-
In compasses constructed according to my Invention the bowl or vessel
charged with the spirits of wine or other suitable liquid and suspended by
gimballs is made of any desired form or outline. Within the said bowl or
vessel, part of which is made of glass or other transparent material, so that
the position of the card can be seen, the magnetic needle or needles and its or
their card are carried or supported on a pivot or between two pivots in the
same manner as they would be if working in air. The above features are

page_text: common to all compasses having the whole or part only of my improve-
ments; to such improvements I will now refer under the following separate
heads-
First, to means for reducing weight and friction on the pivots, and thereby
leaving the needle or needles and its or their card to traverse freely. This I
effect by connecting or combining with the needle or needles and card a
hollow air-tight buoying float of a dome-like or other shape, the said float
being placed over or on a level with, but not lower than the needle or
needles; or I obtain similar advantages by making the card hollow or
attaching a hollow disc-like vessel thereto, and connecting or combining these
with the needle or needles. The weight of the combined parts should be
about the same, preferably rather less, that the weight of the liquid it will
displace in the bowl or vessel.
Secondly, to means for securing the advantages mentioned under the first
head, and also for protecting the magnetic needle or needles from the action
of the liquid thereon. In this case the card is made hollow, or a disc-like
hollow vessel is attached thereto, and the needle or needles placed therein.
And, thirdly, to means for allowing for expansion and contraction of the
liquid in the bowl or vessel by increase or decrease of atmospheric or other
temperature, and under all conditions or circumstances keeping the said bowl
or vessel perfectly full. Here a piece of "doctor" or other ductile metal, or
a piece of india-rubber or other elastic agent preferably corrugated in con-
centric circles, is introduced into or made as part of the bowl or vessel.
The variations in temperature simply cause the piece of metal or elastic
agent to move slightly outwards or inwards as the case may be. Expansion
and contraction can be allowed for by carrying a pipe from the bowl or vessel
and allowing the liquid to flow freely into and from the tube, thereby keeping
the bowl or vessel at all times fully charged.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Alexander Cairns in the Great Seal Patent Office on the 30
14th March 1867.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
CAIRNS, of Liverpool, in the County of Lancaster, Nautical Instrument
Maker, send greeting.

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fourteenth day of September, in the year of our Lord
One thousand eight hundred and sixty-six, in the thirtieth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
Alexander Cairns, Her special license that I, the said Alexander Cairns, my
executors, administrators, and assigns, or such others as I, the said Alexander
Cairns, 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 THE CONSTRUC-
TION OF LIQUID COMPASSES," upon the condition (amongst others) that I, the
said Alexander Cairns, my executors or administrators, by an instrument in
writing under my, or their, or one of their hands 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 Alexander Cairns, 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, reference being had to the accompanying Sheet of Drawings and to
the letters and figures marked thereon (that is to say) :-
In compasses constructed according to my Invention the bowl or vessel
charged with spirits of wine or other liquid and suspended by gimballs is
made of any desired form or outline. Within the said bowl or vessel, part of
which is made of glass or other transparent material, so that the position of
the card can be seen, the magnetic needle or needles and its or their card
are carried or supported on a pivot or between two pivots in the same manner
as they would be if working in air. The above features are common to all
compasses having the whole or part only of my improvements; to such
improvements I will now refer under the following separate heads: -
First, to means for reducing weight and friction on the pivots, and thereby
leaving the needle or needles and its or their card to traverse freely; this I
effect by connecting or combining with the needle or needles and card a hollow
air-tight buoying float of a dome-like or other shape, the said float being
placed over or on a level with, but not lower than the needle or needles; or
I obtain similar advantages by making the card hollow or attaching a hollow

page_text: disc-like vessel thereto, and connecting or combining these with the needle or
needles. The weight of the combined parts should be about the same as
preferably rather more than the weight of the liquid it will displace in the
bowl or vessel.
Secondly, to means for securing the advantages mentioned under the
first head, and also for protecting the magnetic needle or needles from the
action of the liquid thereon. In this case the card is made hollow, or a disc.
like hollow vessel is attached thereto, and the needle or needles placed
therein.
And, thirdly, to means for allowing for expansion and contraction of the liquid
in the bowl or vessel by increase or decrease of atmospheric or other tem-
perature, and under all conditions or circumstances keeping the said bowl or
vessel perfectly full. Here a piece of "doctor" or other ductile metal, or a
piece of india-rubber or other elastic agent, preferably corrugated in con-
centric circles, is introduced into or made as part of the bowl or vessel. The
variations in temperature simply cause the piece of metal or elastic agent to
move slightly outwards or inwards, as the ease may be. Expansion and
contraction can be allowed for by carrying a pipe from the bowl or vessel and
allowing the liquid to flow freely into and from the tube, thereby keeping the
bowl or vessel at all times fully charged.
In the accompanying Sheet of Drawings, which I bave appended that my
Invention may be more readily understood, the improvements under the above
first part are illustrated in Figs. 1, 3, 5, 6, 7, and 8.
Fig. 1 represents a vertical section of a complete compass constructed
according to my Invention, and Fig. 3 a plan of the buoying float and card
shewn in Fig. 1. Both in Figs. 1 and 3 a denotes the compass bowl; b, the
pivot supported by the cross bar c; d, glass cover through which the card 'e is
seen; ff, the buoying float, the dome-like part at the centre being marked
f, and the four assistant radial parts marked f¹; 9, the magnetic needles;
h, the ruby fixed in f. Fig. 5 is a transverse section of a buoying float
marked i, similar to that shewn in Figs. 1 and 3; instead of these being two
long magnetic needles, however, two short ones marked; placed in the samo
Jine are used. Fig. 6 is also a transverse section of another modification of a
buoying float of a dome-like shape to which the card and magnetic needles
mare attached. Figs. 7 and 8 are views also in transverse sections of discs-like
buoying floats n, to which the needles o are attached; in Fig. 7 the top of the
float n serves as the card or space for the required characters, but in Fig. 8
the card is used.

page_text: "
The improvements described under the above head designated "secondly"
are illustrated by the views in transverse sections, Figs. 9 and 10, in
which are disc-like buoying floats with the magnetic needle r therein;
Fig. 10 is arched at its upper central portion, and is provided with a card s;
in Fig. 9 the top of q has the letters or characters enamelled or otherwise
formed thereon.
The third part of my improvements, above designated thirdly, are shewn in
Figs. 1, 2, and 4. In Figs. 1 and 2, the latter being a horizontal section of
the former at the line A, B, t is the concentrically corrugated thin plate of
"doctor" or other metal or material, which is securely attached to the bowl a.
For the purpose of allowing the bowl a to be properly charged with liquid I
employ the screwed pin u attached to t and the nut v. At the time of charging
or filling I turn the nut and thereby draw down u and t into the position shewn
by dotted lines. After driving off all the air bubbles in the liquid through a
small opening in the upper part of a by heat applied in any convenient
manner, and closing the said opening, I slacken the nut vand allow u and t to
rise, and to the extent of the natural tendancy of u to assume a horizontal
position, place the liquid under pressure, by which means the entrance of
air amongst the liquid is entirely prevented. Fig. 4 is a vertical section of
part of a compass bowl with another modification of my Invention for allowing
for expansion and contraction; w is a pipe which descends from the bottom
of the compass bowl x and dips into the partially filled vessel y; the space =
in the said vessel contains air which is compressed by the liquid when it
expands by increase of temperature.
Having now described the nature of my said Invention, and particularized
the same by various modifications capable of being easily carried into effect, I
would here state that under the first part or head I claim, the combination of
the magnetic needle or needles, and a hollow air-tight buoying float when the
said needle or needles is or are connected to the under side of the said float,
substantially as described and illustrated in and by Figs. 1, 3, 5, 6, 7, and 8
on the Sheet of Drawings.
Under the second part or head I claim the combination of the magnetic
needle or needles with a hollow air-tight disc-like buoying float when the said
needle or needles is or are placed in the inside of the said float, substantially
as described and shewn by Figs. 9 and 10 of the Drawings.
Under the third part or head I claim the combination of the concentrically
corrugated plate with the improvements claimed under the above first and
second parts.

page_text: I also claim the pipe u and partially filled vessel y, shewn by Fig. 4 of
the Drawings, as means for allowing for expansion and contraction of the
liquid.
In witness whereof, I, the said Alexander Cairns, have hereunto set
my hand and seal, this Twelfth day of March, in the year of our
Lord One thousand eight hundred and sixty-seven.
In the presence of
JOHN T. KINO,
Of No. 4, Clayton Square,
Liverpool.
ALEXANDER CAIRNS. (L.S.)