IMPROVEMENTS IN SUSPENDING OR APPLYING MARINERS COMPASSES IN VESSELS BUILT OF IRON OR PARTLY OF IRON
Year: 1853

page_text: LETTERS PATENT to William Watson Hewitson, of Springfield
Mount, Leeds, in the County of York, for the Invention
of "IMPROVEMENTS IN SUSPENDING OR APPLYING MARINERS COMPASSES
IN VESSELS BUILT OF IRON OR PARTLY OF IRON."
PROVISIONAL SPECIFICATION left by the said William Watson
Hewitson at the Office of the Commissioners of Patents, with
his Petition, on the 29th January 1853.
I, WILLIAM WATSON HEWITSON, of Springfield Mount, Leeds, in
the County of York, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN SUSPENDING OR APPLYING MARINERS
COMPASSES IN VESSELS BUILT OF IRON OR PARTLY OF IRON" to be as
follows:-
This Invention consists of suspending a mariners compass in or
about the neutral longitudinal axis of a vessel built of iron or
partly of iron; whereby the magnetic influence of the iron on the
needle will be in a state of balance.

page_text: And for this purpose the compass is placed so low in the vessel
as to be at the neutral axis; and, in order that the man at the wheel
may see the card of the compass, a conical funnel is carried up
through the deck or decks, having an eye piece at its upper end,
through which the compass can readily be viewed, and water is
excluded thereby.
SPECIFICATION in pursuance of the conditions of the Letters
Patent, filed by the said William Watson Hewitson in the
Great Seal Patent Office on the 29th July 1853.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I,
WILLIAM WATSON HEWITSON, of Springfield Mount, Leeds, in the
County of York, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-ninth day of January,
in the year of our Lord One thousand eight hundred and fifty-three,
in the sixteenth year of Her reign, did, for Herself, Her heirs and
successors, give and grant unto me, the said William Watson
Hewitson, Her special licence that I, the said William Watson
Hewitson, my executors, administrators, and assigns, or such others
as I, the said William Watson Hewitson, my executors, adminis-
trators, 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 "IMPROVE-
MENTS IN SUSPENDING OR APPLYING MARINERS COMPASSES IN VESSELS BUILT
OF IRON OR PARTLY OF IRON," upon the condition (amongst others)
that I, the said William Watson Hewitson, 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

page_text: 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 William Watson Hewitson,
do hereby declare the nature of the said Invention, and in what
manner the same is to be performed, to be particularly described
and ascertained in and by the following statement thereof (that is
to say):
I claim as my Invention and improvement the fixing of the
"mariners compass" in such a position that it will be at or near to
that point which may be called the neutral axis of that portion of
iron which forms part of the ship, and which portion is cut by a
vertical line passing through the binnacle or compass, and at right
angles to the keel.
I do not propose to alter the position of the compass with
reference to the distance at which it is usually fixed from the stem
and stern of the vessel, but, when convenient, would prefer to
place it about midway between these two points, and at or near the
centre of the mass of iron, which would be cut by another line
passing longitudinally and vertically through the ship.
In Figure 1, I have shewn a cross section marked n, n, n, n, n, of a
three-decked iron ship with the compass hung in the manner I claim
as my improvement; and in Figure 2, I have shewn a longitudinal
section of the same. In Figure 1, the point marked a is very nearly
the centre or point at which the attraction or influence of the iron
over the needle is equal in every direction (in the plane of this
section,) and therefore the vessel may be laid over on either side and
at any angle (so long as she is not unmanageable) without materially
affecting the needle of the compass.
To find the position of the point marked a, I estimate the amount
of surface in the iron at this section for any short length, say twelve
inches, and then by calculation obtain the mean centre of the
whole mass, taking into account the amount of force with which
each portion of this surface will act upon the needle, because the
nearer any portion of the iron is placed to the needle, the greater the
attraction or influence it will exert upon it, and vice versa. When

page_text: this point is determined, I provide a compass manufactured in the
ordinary manner, with brass bowl and gymbals complete; taking
care to have the card of such a size that it shall subtend, or nearly
subtend, the same angle, with the eye of the man at the wheel,
as a card of the size in common use placed at the usual distance;
i. e. that as the card will be at a much greater distance from
the eye (as fixed in my improved plan) it must be made as much
larger as will ensure its being seen as distinctly and read as con-
veniently as if it were only two or three feet distant. When the
bowl is firmly fixed in its proper position, I provide a strong
wooden case of the form shewn by the lines marked c, c, c, c, (Figures
1 and 2), square at the bottom (so that the bowl and gymbals in
which the compass is hung will have sufficient room to work with.
the motion of the vessel without coming into contact with the inside
surface of the case or covering), and either tapered up towards
the top, as shown by the letters c, c, c, c, Figures 1 and 2, or
expanded sideways to three or four feet long at the top, by two or
three inches wide inside, as shewn by the letters c¹, c¹, c¹, c¹, so that
the man at the wheel, on whichever side he may be standing, will
be able to look down and see the card without leaving his place.
The funnel or case may be made of any suitable material, and
must go through the deck or decks, and be firmly fixed thereto,
being at the same time made water-tight, so that the compass and
other apparatus may be secure from breakage or injury from the
weather.
The gymbals and compass must be securely and independently
fixed to the deck nearest to which it is found most convenient to
place them. I also insert a piece of plate glass of suitable thick-
ness into the opening at the top of the funnel or case, as shewn at
ffff, to prevent water or dirt getting on to the card. I also pro-
vide a lamp, such as is shewn at g, Figure 2, with suitable reflectors
h, h, h, h, and placed so that the face of the card may be sufficiently
illuminated for the man to see to steer distinctly. The funnel or
card must be made so that the light from the lamp and reflectors
may pass freely and without interruption to the face of the card,

page_text: the case or funnel having a door or opening in the side, (and capable
of being securely closed), so as to give free access to the lamp and
reflectors when required for trimming or cleaning, &c.
The line d, d, Figure 1, shows the relative mass of iron surface on
each side of the compass, as fixed on my improved plan, (when the
ship is laid over,) compared with the mass on each side of the com-
pass as usually fixed at b, and shewn by the relative quantity on
each side of the line e, e; and it will be readily seen that the line
d, d, nearly, if not exactly, divides the mass of iron in this section
into two equal parts; whereas the line e, e, has nearly twice as
much on one side as the other; and it is in the mode of obviating
this change or fluctuation in the quantity of iron on either side of
a vertical line passing through the needle that I claim as my
Invention and improvement.
In witness whereof, I, the said William Watson Hewitson, have
hereunto set my hand and seal, this Twenty-ninth day of
July, in the year of our Lord One thousand eight hundred
and fifty-three.
0
Witness
H. W. CARPMAEL.
WILLIAM W. HEWITSON. (L.S.)