IMPROVEMENTS IN MARINE SCREW PROPELLERS
Year: 1861

page_text: LETTERS PATENT to William Welch, of 27, King Street, Southsea,
Portsmouth, in the County of Hants, for the Invention of "IMPROVEMENTS
IN MARINE SCREW PROPELLERS."
Sealed the 4th April 1862, and dated the 17th October 1861.
PROVISIONAL SPECIFICATION left by the said William Welch at the
Office of the Commissioners of Patents, with his Petition, on the 17th
October 1861.
I, WILLIAM WELCH, of 27, King Street, Southsea, Portsmouth, in the
County of Hants, do hereby declare the nature of the Invention for "IMPROVE-
MENTS IN MARINE SCREW PROPELLERS," to be as follows:-
My Invention relates to the position and form of the spiral curvature and
cylindrical surface of the blade or blades, which instead of varying in their
width of surface shall be of uniform dimensions throughout their entire length,
and the outer or entering ends of the blades instead of maintaining the pitch
or passing the axis at an angle are made the neutral or vanishing points of
the screw, and rotating in a disc form in a line at a right angle with the axis
or parallel with the midship section of the vessel, while the conjunction of the
blades with the propeller shaft is placed at a right angle with the opposing
end or parallel with the water line, each blade thus forming a curved cylin-
drical surface, the ends crossing at an angle = 45°, or both blades combined

page_text: producing a true screw, the ends crossing at an angle = 90°; the greater pitch
of the screw is thus placed at a point on each blade about one half the radius
of the blade from the propeller shaft, the entire driving pitch is thus passed
over and the angle best suited to the vessel realized without the aid of shifting
blades, and an additional impulse given to the water, backward or forward, by
the combined centripetal and centrifugal tendency obtained by the neutral
points at the ends of the blades, as also destroying the vibrating influence
consequent with curved surfaces whose vanishing points are at a distance from
the end of the blades, and which also produce a centrifugal tendency to the
outer current beyond the diameter of the screw detrimental to the progress of
the vessel. The principle involved in this Invention is the producing a screw
propeller of one, two, or more blades whose force shall be equal and continuous
in all its actions, and whose neutral or vanishing points shall be complete
within the surface of a globe whose axis is equal to the diameter of the length
of the blades. Screw propellers constructed on this principle will produce the
desideratum over those heretofore used.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Welch in the Great Seal Patent Office on the 17th
April 1862.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
WELCH, of 27, King Street, Southsea, Portsmouth, in the County of Hants,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Seventeenth day of October, in the year of our
Lord One thousand eight hundred and sixty-one, in the twenty-fifth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said William Welch, Her special licence that I, the said William
Welch, my executors, administrators, and assigns, or such others as I, the
said William Welch, 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 "IMPROVE-
MENTS IN MARINE SCREW PROPELLERS," upon the condition (amongst others) that
I, the said William Welch, my executors or administrators, by an instrument

page_text: 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 William Welch, do hereby declare
the nature of the 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 thereof, that is to say :-
=
My Invention relates to the position and form of the spiral curvature and
cylindrical surface of the blade or blades, which instead of varying in their
width of surface shall be of uniform dimensions throughout their entire length,
and the outer or entering ends of the blades instead of maintaining the pitch
or passing the axis at an angle are made the neutral or vanishing points of
the screw, and rotating in a disc form in a line at a right angle with the axis
or parallel with the midship section of the vessel, while the conjunction of the
blades with the propeller shaft is placed at a right angle with the opposing
end or parallel with the water line, each blade thus forming a curved cylin-
drical surface, the ends crossing at an angle
45°; or both blades combined
producing a true screw, the ends crossing at an angle = 90°; the greater pitch
of the screw is thus placed at a point on each blade about one half the radius
of the blade from the propeller shaft, the entire driving pitch is thus passed
over and the angle best suited to the vessel realized without the aid of shifting
blades, and an additional impulse given to the water, backward or forward, by
the combined centripetal and centrifugal tendency obtained by the neutral
points at the ends of the blades, as also destroying the vibrating influence
consequent with curved surfaces whose vanishing points are at a distance from
the end of the blades, and which also produce a centrifugal tendency to the
outer current beyond the diameter of the screw detrimental to the progress of
the vessel.
Having thus stated the nature of my Invention, I now proceed to describe
the manner of performing the same, reference being had to the illustrative
Sheet of Drawings hereunto annexed, and to the references marked thereon,
as follows:-
DESCRIPTION OF THE DRAWINGS.
Figure 1 represents a globe whose axis shall equal the diameter of the
required "screw propeller;" on the surface of the globe I describe six equal

page_text: circles whose lines of circumduction shall intersect each other over the entire
sphere from four points of such intersections, as at B, C, D, E, straight lines
are produced through the centre of the globe, crossing at right angles, which
constitute a double axis, such as would be described at the "
poles and
equator;" from these intersections on the surface a double waved line is
formed around the entire circumference, either of which being traced will
divide the surface into two equal parts, which line shall constitute the curved
form at the periphery of the "screw blades." From the line thus described,
as shewn at Figure 2, a curvilinear surface is formed, intersecting the centre
of the globe at the point where the two axes unite, as shown at A, produced
in the following manner, viz., from the point of intersection on the surface
at B, set off any number of equal distances on the line from B to C, also from
B to D, the same being observed on the lines from E, on C, D; from these
points draw straight lines parallel with the axis A, C, D, the intersections of
which will produce the desired curvilinear form of surface for the "screw
blades." The form of surfaces and periphery thus produced, supplied with a
boss at the line of either axis, which line shall be produced in the centre of
the driving shaft, shall constitute the entire form, thus describing a complete
helix, sphere, or universal screw, as shown on Figures 2, 3, and 4. Any sec-
tional width of blade may be used, the dimensions of which will depend upon
the diameter required, combined with the number of revolutions per minute
and the amount of engine power to be consumed, the width of surface to be of
equal dimensions on each side of the opposite axis or centre line of the blade.
A sectional form thus produced is shown at Figures 5 and 6, as revolving on
the axis A, C, D. The width of blade proportionate to the existing diameters
and arrangements of vessels will require to be about equal to parallel lines
that would be produced from the points of intersections described by the
inclination of the "axis of the earth" towards the "ecliptic," and the limit of
whose revolutions should not exceed per minute the number of degrees between
the "poles" and "equator," viz., 180. "Screw propellers" constructed on
this principle will produce a refraction of the water acted upon conformable
with the laws of the refraction of light passing through a transparent medium
whose spherical surfaces equal the curved form of the edges of the blades when
revolving, as shewn at Figures 2 and 6.
Having now described the nature of my said Invention of "Improvements
in Screw Propellers," and the manner in which the same is to be performed,
I would remark, in conclusion, that what I claim as my Invention intended to
be secured to me by the herein in part recited Letters Patent is the mode

page_text: of constructing the blades of screw propellers so as to combine these two
curvatures in the form of their acting surfaces, in the manner shown by the
accompanying Sheet of Drawings and herein described for the purposes set
forth.
In witness whereof, I, the said William Welch, have hereunto set my
hand and seal, this Twenty-eighth day of February, in the year of our
Lord One thousand eight hundred and sixty-two.
Signed, sealed, and delivered by
the said William Welch, in
the presence of
CHARLES HENRY BINSTEED,
Sol. & Notary,
Portsmouth.
WILLIAM WELCH. (L.S.)