IMPROVEMENTS IN SHIPS' MASTS
Year: 1862

page_text: LETTERS PATENT to Charles Harratt, of Hornsey Lane, Highgate, in the
County of Middlesex, for the Invention of "IMPROVEMENTS IN SHIPS'
MASTS."
Sealed the 17th March 1863, and dated the 14th October 1862.
PROVISIONAL SPECIFICATION left by the said Charles Harratt at the
Office of the Commissioners of Patents, with his Petition, on the 14th
October 1862.
I, CHARLES HARRATT, of Hornsey Lane, Highgate, in the County of
Middlesex, do hereby declaré the nature of the Invention for "IMPROVEMENTS
IN SHIPS' MASTS," to be as follows:-
This Invention has for its object improvements in ships' masts. For these
purposes, in order that the ordinary stays and rigging may be dispensed with
and a mast constructed in a suitable manner to bear the strain consequent on
the use of sails, such mast may be constructed of wood, or partly of wood and
iron, or wholly of iron. The peculiarity consists in giving additional strength
to a mast by applying projecting ribs from the upper to the lower end. The
ribs are made to project more extensively and are of greater strength where
the greater strains come on the mast, and they are reduced in section and
extent of projection where the mast is subject to less strain. The form of ribs
preferred are such as present a slightly concave face from top to bottom,
projecting more extensively at the deck than at the upper or lower end of the
mast; but the form and extent of the projection may be varied. The number

page_text: of such projecting ribs to a-mast may be varied, depending on the nature of
the mast and the greater strength desired to be given to the same by the
projecting ribs.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Charles Harratt in the Great Seal Patent Office on the
14th April 1863.
'
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
HARRATT, of Hornsey Lane, Highgate, in the County of Middlesex, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fourteenth day of October, in the year of our
Lord One thousand eight hundred and sixty-two, in the twenty-sixth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Charles Harratt, Her special licence that I, the said Charles
Harratt, my executors, administrators, and assigns, or such others as I, the
said Charles Harratt, 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' MASTS," upon the condition (amongst others) that the said Charles
Harratt, 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 Charles Harratt, 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:-
On the 18th of March 1853 I obtained Letters Patent, (No. 673,) for a method
of strengthening masts, so as to allow the yards and sails to be swung all
round the mast, and its rigging covering the whole from the wind. This was
effected by a system of iron stays, or rods of iron in one piece, brought to act
on the mast by studs or props to hold out the rods in a form properly to
strengthen every part of the mast. Thus, on the windward side the rods acted

page_text: as stays and upon the lee side as flying buttresses, their efficacy depending, in
this last case, a good deal upon the proportion between the weight assigned to
the rods and the weight assigned.to the mast itself..
I now construct a mast and its supports in manner following, regard being
had to a proper distribution of the weight:-Draw the hyperbolic curve Ppp,
Figure 1, its equation referred to the centre C, and asymptotes XY for

page_text: lengths are placed outside the shorter, so as to form the hyperbolic curve,
Figure 1, in the manner of carriage springs; since the strength of rolled iron
lies in its skin, the greater the number of strips the stronger the buttress. To
resist torsion or any change of: form, iron bands encircle both mast and but-
tresses at intervals of about five feet, and the space between each buttress,
-underneath this band, is filled up with teak, as shewn in Figure 5; these
bands cover all joints and are rivetted to the mast through the buttresses or
the teak. Thus may be constructed, at moderate cost, a mast strong enough
without stays to stand up against all the efforts of the wind upon the sails;
it must be well stepped and firmly fastened to the bottom of the ship. A
common timber mast may be buttressed similarly. Figure 6 shews a mast
thus rigged; an iron hoop fixed upon the cross trees is grooved so as to hold
a collar, which is free to move all round the hoop and carry with it the yard
and sail; there is a similar hoop and collar on deck to carry round the foot of
the sail. Thus the sail may be set to windward on either tack, covering the
mast and shrouds from the wind and forming the best of all possible stays.
In sailing upon oblique courses the great advantage of this rig is obvious.
In witness whereof, I, the said Charles Harratt, have hereunto set my
hand and seal, this Eleventh day of April, in the year of our Lord
One thousand eight hundred and sixty-three.
CHARLES HARRATT.
(L.S.)