IMPROVEMENTS IN PROPELLERS FOR PROPELLING VESSELS
Year: 1863

page_text: LETTERS PATENT to John McGrigor Croft, of No. 8, Abbey Road,
Saint John's Wood, in the County of Middlesex, Doctor of Medicine,
for the Invention of "IMPROVEMENTS IN PROPELLERS FOR PROPELLING
VESSELS."
Sealed the 29th December 1868, and dated the 6th July 1863.
PROVISIONAL SPECIFICATION left by the said John McGrigor Croft
at the Office of the Commissioners of Patents, with his Petition, on
the 6th July 1863..
I, JOHN MCGRIGOR CROFT, of No. 8, Abbey Road, Saint John's Wood,
5 in the County of Middlesex, Doctor of Medicine, do hereby declare the
nature of the said Invention for "IMPROVEMENTS IN PROPELLERS FOR PRÓ-
PELLING VESSELS," to be as follows:-
My Invention consists in the use and adoption of a wheel similar to the
frame of an ordinary paddle wheel, but provided in lieu of the float boards
hitherto employed with spiral, curved, or oblique blades secured to the frame
aforesaid. A pair of wheels of the character aforesaid can be used one on
each side of the vessel like the ordinary paddle wheels, or under the "quarters,""
and may be partially or wholly submerged, and more than one pair may be
adopted if thought requisite. If desired, one wheel provided with the blades
aforesaid, and enclosed in a box or case may be adopted; also my Invention
might, if desired, be adopted for stern propelling.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John McGrigor Croft in the Great Seal Patent
Office on the 6th January 1864.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
McGRIGOR CROFT, of No. 8, Abbey Road, St. John's Wood, in the County of
Middlesex, Doctor of Medicine, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Sixth day of July, in the year of our Lord One
thousand eight hundred and sixty-three, in the twenty-seventh year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said John McGrigor Croft, Her special licence that I, the said John
McGrigor Croft, my executors, administrators, and assigns, or such others
as I, the said John McGrigor Croft, 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 PROPELLERS FOR PROPELLING VESSELS," upon
the condition (amongst others) that I, the said John M°Grigor Croft,
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 John McGrigor Croft, 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:_
My improvements relate to propellers of that kind where. the floats or
propelling surfaces are so arranged as to form (together the necessary
framing) wheels, being thus far the same in character as the ordinary paddle
wheels; but by the adoption of my improvements, instead of using for the
floats flat boards or pieces set at right angles or nearly so, I use the duplicate
arrangement of diagonal curved floats or propelling surfaces herein-after
described and illustrated by the accompanying Drawings.
A pair of wheels of the character aforesaid can be used one on each side of
the vessel like the ordinary paddle wheel, or under the quarters, or in any

page_text: convenient position, and may be partially or wholly submerged, and more than
one pair of these wheels may be adopted if desired; also I prefer to make
my improved floats of iron or other metal. I further prefer to construct my
improved propeller or paddle wheels as follows:-To the iron arms which
proceed from the boss of the wheel to the rim of the circle of the wheel per-
pendicularly or obliquely I attach floats or propelling surfaces twisted at an
angle of 45 degrees; this pitch, however, may deviate from if necessary.
The floats or propelling surfaces are fixed in pairs opposite each other, or in
other words, the floats or propelling surfaces ranged along the one annulus of
the wheel are opposite the duplicates thereof on the other annulus of the
wheel. The floats or propelling surfaces are fixed on the arms aforesaid, and
secured transversely at the base by a bar of metal extending across to the
arms of the wheel, and the whole may be secured by means of screws or bolts.
Series of these floats or propelling surfaces are extended around the inner sides
of the circles of the wheels.
Although I have shewn by the accompanying Drawings the floats arranged
so as to tend obliquely towards each other, both sets of floats or propelling
surfaces may incline in one way so as to throw the water (when in action)
under the vessel. I do not, however, confine myself to any particular number
of floats or propelling surfaces, or any particular mode of fixture thereof, and
the floats or propelling surfaces may be crenated or ribbed in their moulding
or construction to give further grip of the water...
By means of my propeller wheel I purpose to obtain the following advan-
tages-Propeller wheels considerably smaller than paddle wheels with the
floats as heretofore adopted; greater speed, there not being the usual paddle
backwater; no vibration; less consumption of fuel and steam. The vessel
being less immersed in the water by the action of my propellers, contrary to to
the effect produced by the ordinary paddle wheels. Furthermore, my propeller
wheels will clear away obstructions, such as ice and other obstacles, by their.
own proper
action without the chance of injury which frequently occurs to
the paddle floats and to the stern propellers.
It will be seen that my propellers, although not likely to get out of order,
may be easily repaired when damaged, and though of great strength, present
little obstruction to a gale of wind or sea. Furthermore, my propellers will
induce the vessel to answer to the helm more quickly than with screw propeller
or ordinary paddle wheels; likewise my propeller may be much narrower
than float paddles, and present little surface transversely, and a vessel of nar-
rower beam will be kept free from heavy rolling in a sea way by the peculiar
motion of my floats on the sea.

page_text: Having thus described the nature of my said Invention, and intimated in,
what manner the same is to be performed, I will now, in order to the full
explication thereof, describe the illustrative Drawings accompanying this
Specification, by the words, figures, and letters following, that is to say :-
DESCRIPTION OF THE DRAWINGS.
Fig. 1, half elevation; Fig. 2, half section; Fig. 3, cross section; Fig. 4,
end elevation. .
A denotes one of the rims or circumferential annueli of the wheel; B, the
boss; C, the engine shaft; D, the floats or propelling surfaces; E, the iron
armis which proceed from the boss (B) of the wheel; F, bars of metal extend-
ing across to the arms of the wheel, and securing the floats or propelling
. surfaces; G, stays also for firmly securing the floats.
(Note.) The various arrangements shown by the Drawings, or herein
described may be varied as the requirements of construction may demand.
Having now particularly described the nature of the said Invention, and
in what manner the same is to be performed, I hereby declare that I claim in
respect thereof the duplicate arrangements of diagonal curved floats or pro-
pelling surfaces, as herein-before set forth, the mere details of construction
when taken and considered apart from the purposes of my said Invention not
being claimed as being within the scope of my Letters Patent aforesaid.
In witness whereof, I, the said John McGrigor Croft, have hereunto
set my hand and seal, this Sixth day of January, in the year of our
Lord One thousand and eight hundred and sixty-four.
Witness,
GEORGE MARSHALL.
JOHN MCGRIGOR CROFT. (L.S.)