IMPROVEMENTS IN THE MEANS OF RENDERING MAGNETIC. NEEDLES LESS PREJUDICIALLY INFLUENCED BY LOCAL ATTRACTION, WHICH IMPROVE- MENTS ARE APPLICABLE TO OTHER MAGNETIC OBJECTS. FOR THE SAME PURPOSES
Year: 1839

page_text: . TO ALL TO WHOM THESE PRESENTS SHALL COME, I,. Baron
HENRY DE BODE, of Great Portland Street, Cavendish Square, in the County
of Middlesex, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Letters Patent under the Great Seal of Great Britain, bearing date at West-
minster, the Eighth day of June, in the second year of Her reign, did, for
Herself, Her heirs and successors, give and grant unto me, the said Baron
Henry de Bode, Her especial licence, full power, sole privilege and authority,
that I, the said Baron Henry de Bode, my exors, admors, and assigns, or such
others as I, the said Baron Henry de Bode; 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, should and lawfully might make, use,.
exercise, and vend, within England,. Wales, and the Town of Berwick-upon-
Tweed, my Invention of "IMPROVEMENTS IN THE MEANS OF RENDERING MAGNETIC.
NEEDLES LESS PREJUDICIALLY INFLUENCED BY LOCAL ATTRACTION, WHICH IMPROVE-
MENTS ARE APPLICABLE TO OTHER MAGNETIC OBJECTS. FOR THE SAME PURPOSES;"
in which said Letters Patent is contained a proviso that. I,. the said Baron
Henry de Bode, shall cause a particular description of the nature of the said
Invention, and in what manner the same is to be performed; to be inrolled in
Her said 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 largo
appear.

page_text: NOW KNOW YE, that in compliance with the said proviso. I, the said
Baron Henry de Bode, do hereby declare the nature of my said Invention,
and the manner in which the same is to be performed, are fully described and
ascertained in and by the following statement thereof, reference being had to
the Drawing hereunto annexed, and to the figures and letters marked thereon
(that is to say):-
My Invention relates to a mode of constructing apparatus to contain a
magnetic needle in such manner as to offer modia between the magnetic
needle and the local quantities of iron, which will materially prevent the effect
of such local quantities of iron in attracting the needle in a manner pre-
judicially to injure the correct pointing of such magnetic needle. And in
order to give the best information in my power, I will proceed to describe the
Drawing hereunto annexed.
The Drawing represents the section of a mariner's compass, the magnetic 1
needle of which is placed in a compound vessel constructed according to my
Invention.
The vessel in which the magnetic needle and card a is placed consists of a
double glass vessel 6, the space between the double vessel b being filled with
quicksilver c, and by this means I am enabled to get what may be called a 2
metallic surface of quicksilver within two surfaces of glass between the
magnetic needle and the local quantity of iron, and such an arrangement will
be found materially to prevent the needle being prejudicially influenced by the
local iron. The standard d, which carries the point for the card and magnetic
needle, is cemented to the lower part of the inner vessel b, and d¹ is an opening?
through which the quicksilver is introduced between the two surfaces of
glass b, b, the opening d¹ being closed with a stopper or plug, as will readily be
traced by examining the Drawing.
The vessel b is placed within an outer vessel of lead, consisting of two
thicknesses of lead, which is a metal little effected by the attractions or fluids &
which influence the magnetic needle, and there is, by preference, a thickness
of glass between the double lead vessel. And e is a brass strap by which the
compound vessel containing the compass is suspended on the ordinary gimbles.
f is a glass in a suitable frame forming a corner to the vessel; it will be seen
that this glass is concave, which allows of more play to the card a, but will
prevent its being thrown off the point. I would, however, remark that a flat
glass may be used if preferred.
Having thus described the nature of my Invention, I would, in conclusion,

page_text: remark that it will be evident that by placing a chronometer in a similar vessel
as that above described the errors which have been found to be produced by
magnetic influences would be materially lessened if not wholly prevented.
And I would have it understood that what I claim as my Invention is the
mode herein described of rendering magnetic needles less prejudicially acted
on by local attraction, and which mode, as above described, is applicable to
other purposes.
In witness whereof, I, the said Baron Henry de Bode, have hereunto
set my hand and seal, this Seventh day of December, in the year of our
Lord One thousand eight hundred and thirty-nine.
BARON HENRY (L.B.) DE BODE.
AND BE IT REMEMBERED, that on the Seventh day of December, in the
year of our Lord 1839, the aforesaid Baron Henry de Bode came before our
said Lady the Queen in Her Chancery, and acknowledged the Specification
aforesaid, and all and every thing therein contained and specified, in form
above written. And also the Specification aforesaid was stamped according to
the tenor of the Statute made for that purpose.
Inrolled the Seventh day of December, in the year of our Lord One
thousand eight hundred and thirty-nine.