IMPROVEMENTS IN THE MANUFACTURE OF METALLIC BOATS
Year: 1856

page_text: LETTERS PATENT to Joseph Francis, of New York, in the United States
of America, Engineer, for the Invention of "IMPROVEMENTS IN THE
MANUFACTURE OF METALLIC BOATS."
Sealed the 22nd April 1856, and dated the 22nd January 1856.
PROVISIONAL SPECIFICATION left by the said Joseph Francis at the
Office of the Commissioners of Patents, with his Petition, on the 22nd
January 1856.
I, JOSEPH FRANCIS, of New York, in the United States of America, Engineer,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN THE
MANUFACTURE OF METALLIC BOATS," to be as follows:-
The object of this Invention is to manufacture metallic boats with greater
facility and economy than heretofore. For this purpose, I prepare.pairs of
dies, which shall together form a counterpart of the boat to be manufactured;
and in the face of these dies I make corresponding undulations, for the purpose
of corrugating the metal while it is being brought to shape by pressure between
the dies. Sheets of metal thus prepared, and severally shaped to suit their
respective local destinations, are connected together by lap joints and bolted to
the keel of the boat. The corrugations I prefer to make in sectional form, of a
quarter circle, struck from the plane of the sheet or plate, and terminating in
an inclined straight line. This sectional figure permits of the bending over of
the plates, to increase the width of the boat to any required amount, without
diminishing, to an appreciable extent, the strength of the metal; and I am
thus enabled to form boats of various sizes from one set of dies. In shaping

page_text: the sheets of metal that are tó form the head of the boat, I give the corru-
gations a gradually increasing depth as the expanse of surface for the sheet to
occupy diminishes; and I am thus: enabled to take up the surplus metal,
and with it to impart great additional strength to the boat.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Joseph Francis in the Great Seal Patent Office on the
21st July 1856.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOSEPH
FRANCIS, of New York, in the United States of America, Engineer, send
greeting.
WHEREAS Her most Excellent 'Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-second day of January, in the
year of our.
Lord One thousand eight hundred and fifty-six, in the nineteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Joseph Francis, Her special license that I, the said Joseph Francis, my
executors, administrators, and assigns, or such others as I, the said Joseph
Francis, 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 MANUFACTURE OF METALLIC BOATS," upon the condition (amongst others)
that I, the said Joseph Francis; 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 mouths
next and immediately after the date of the said Letters Patent..
NOW KNOW YE; that I, the said Joseph' Francis, do hereby. declare
the nature of my said Invention, and in what manner the same is to-be
performed, to be particularly described and ascertained in and by the following
statement, reference being had to the Drawing hereunto annexed; and-to the
letters and figures marked thereon (that is to say):-
This Invention relates to the manufacture of boats from sheets of corrugated
metal, and consists in certain modifications of my original Invention (for which
an English Patent was obtained on my behalf on the Twenty-fourth day of
May, One thousand eight hundred and forty-five, in the name of Julius Adolph

page_text: Detmold), whereby I am enabled to manufacture boats of various sizes from
one and the same set of dies. By this means I am enabled so to reduce the
cost of the machinery or apparatus required in the manufacture (and conse-
quently the cost of the manufactured articles) as to adapt my corrugated
metal boats to the requirements of all branches of the mercantile service.
The chief advantage of this class of boats is, that with comparatively little
weight of material (and consequently little cost) great strength is obtained,
sufficient to ensure the stability of the structure even when driven upon rocks
by the force of a tempestuous sea, or subjected to the concussion of cannon.
In the Specification of the Patent above referred to, I propose to employ a
half round corrugation, to give rigidity to the sheets of metal which formed the
sides of the boat, and also to take up the surplus metal at the parts of the sheet
where a contracted surface was required to conform to the curved lines at the
head and stern; but this shape of corrugation, running in one unbroken-line
from head to stern, although imparting great strength to the boat, rendered its,
manufacture too costly for practical purposes, inasmuch as for every sized
boat a separate set of dies was required. To remedy this defect, I have so
modified the form of the corrugation as to admit of a sheet of corrugated metal
being bent to any required sectional figure, to suit boats of different breadths
and models without deducting materially from the resisting strength of the
corrugations, and to provide for varying the length and breadth of boats; I form
the sides thereof of sheets of metal, set breadthwise along the keel, and jointed
together by lap joints running parallel or nearly parallel with each other from
the gunwale to the keel.
In the accompanying Drawing, Fig. 1 shews, in side elevation, a metal
boat, constructed on this principle; Fig. 2 is a plan view of the same; Fig. 3
is a cross section, taken through the middle of the boat at the line 1, 2, of
Fig. 2; and Fig. 4 is a cross section, taken through the line 3, 4, of the same
Figure, and shewing the bulkhead of the air chamber in elevation. The boat,
it will be seen, is composed of plates or sheets of corrugated metal, of different
forms, examples of which are given in the detached views, Figs. 5 and 6.
These plates are brought to shape by pressure between fixed and stationary
dies, the moving dies being forced upwards against the fixed. dies by. means
of hydraulic or other pressure. The form of the corrugation will be best seen
by reference to the Diagram, Fig. 7, which represents, in edge view, a portion
of a plate in full-size. The Figure of the corrugation may be described as
a quarter circle a, struck from the plane 6, 6, and continued in a straight line c
(or a slight curvature may be substituted) to the point d on the plane b. The
distance apart of the points d, or in other words the breadth of the corrugations,

page_text: may vary; but I have found by experiments that corrugations about four inches
broad (the proportion given in the Drawing) will answer the best. At those
parts, where increased or unequal contraction or expansion of the plate is.
required to prevent buckling, the depth of the corrugations must be gradually
increased or decreased, as the case may be. The variations of depth which
I have found to answer are from five-eighths of an inch to three-fourths of an
inch. It should be remarked that, in order to impart great rigidity to thin
sheets of metal by corrugating the same, it is desirable to approach in the
sectional form of the corrugation as near to a right angle as the metal will
permit without fracture. This I have attained in the corrugation which
I employ, and while obtaining the required rigidity, I am enabled to adapt the
plates to different forms and dimensions of boats, as will be now described.
The plates prepared as above indicated, I connect together and to the keel
by rivets, as shewn in the several views of the boat, lapping the edges of the
several plates over the adjoining plates, whereby I form a stiff shell, having
joints of about two and a half inches in breadth, and requiring no braces or
angle iron to keep it in shape.
It now remains to explain how boats of various sizes may be constructed by
the use of one and the same set of dies. To construct the boat represented at
Figs. 1 and 2, eight breadths of corrugated plates are supposed to be required
to complete its length. Now, supposing these plates each to measure three feet
in breadth, and that it is required to form a boat three feet longer than that
shewn in the Drawing, this may be readily effected by applying an additional
pair of plates between the plates a and b on the opposite sides of the boat; and
if it be desired at the same time to enlarge the proportion of the boat at the
bows and sides, the plates of metal may be bent outwards to the dotted
positions c and d of Figs. 5 and 6, the form of the corrugation being such as
will admit of this bending back of the plate without rupturing the metal even
when metal of only ordinary quality is used; the boat will then assume the
proportions indicated by the dotted lines Fig. 2. The opposite effect, that is,
the construction of a boat of smaller dimensions than that for which the set of
dies was prepared, may be obtained by diminishing the number of the plates,
and by bending inwards those used, and increasing the width of the lap joints.
By these means, the width of the bows of the boat may be contracted, as
desired, and increased strength may be imparted thereto. If, then, a medium
size of boat be chosen as a model for the corrugating and shaping dies, a great
variety of proportions of boats may be built from plates or sheets of metal
prepared from such dies, and thus the cost of manufacture will be sufficiently
reduced to bring the Invention into profitable and general use.

page_text: Having now explained the nature and object of my Invention of improve-
ments in the manufacture of metallic boats, and set forth the manner of
carrying the same into effect, I wish it to be understood, that under the above
in part recited Letters Patent I claim, the manufacture of boats from sheets.
or plates of metal, corrugated and jointed together in the manner and for the
purpose above described,
In witness whereof, I, the said Joseph Francis, have hereunto set my
hand and seal, the Fifteenth day of July, in the year of our Lord
One thousand eight hundred and fifty-six.
Witness,
FRED. WALKDEN,
66, Chancery Lane.
JOSEPH FRANCIS. (L.S.)