AN IMPROVEMENT IN SCREW PROPELLERS
Year: 1854

page_text: LETTERS PATENT to Richard Archibald Brooman, of 166, Fleet Street, in
the City of London, Patent Agent, for the Invention of "AN IMPROVEMENT
PROVISIONAL SPECIFICATION left by the said Richard Archibald
Brooman at the Office of the Commissioners of Patents, with his
Petition, on the 5th June 1854.
I, RICHARD ARCHIBALD BROOMAN, of 166, Fleet Street, in the City of
London, Patent Agent, do hereby declare the nature of the said Invention for
"AN IMPROVEMENT IN SCREW PROPELLERS," (communicated to me by a foreigner
residing abroad), to be as follows:-
'This Invention consists in making the peripheries of the blades at every
point equidistant from the axis of rotation, and then attaching to the periphery
of each blade a rim or flange turning backward to enclose the water acted upon
by the surface of the blade, whereby the water is prevented from being thrown
outward by the centrifugal force generated by the revolution of the propeller.
By this construction the power is expended more directly in the line of the
axis of the instrument, not being wasted laterally, and thus the maximum of
useful effect is more nearly attained.
This propeller will be found to be peculiarly valuable for canal navigation,
since there is no lateral disturbance of the water to produce injurious action
upon the banks.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Richard Archibald Brooman in the Great Scal Patent Office
on the 5th December 1854.
TO ALL TO WHOM THESE PRESENTS SHALL COME, J, RICHARD
ARCHIBALD BROOMAN, of 166, Fleet Street, in the City of London, Patent
Agent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fifth day of June, in the year of our Lord One
thousand eight hundred and fifty-four, in the seventeenth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
Richard Archibald Brooman, Her special licence that I, the said Richard
Archibald Brooman, my executors, administrators, and assigns, or such others
as I, the said Richard Archibald Brooman, 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
"AN IMPROVEMENT IN SCREW PROPELLERS," (communicated to me by a foreigner
residing abroad), upon the condition (amongst others) that I, the said Richard
Archibald Brooman, by an instrument in writing under my hand and senl,
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 Richard Archibald Brooman, 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, reference being had to the Drawing hereunto
annexed, that is to say:-
This Invention consists in making the peripheries of the blades at every
point equidistant from the axis of rotation, and then attaching to the periphery
of each blade a rim or flange turning backward to enclose the water acted upon
by the surface of the blade, whereby the water is prevented from being thrown
outward by the centrifugal force generated by the revolution of the propeller.
By this construction the power is expended more directly in the line of the
axis of the instrument, not being wasted laterally, and thus the maximum of
useful effect is more nearly attained.
This propeller will be found to be peculiarly valuable for canal navigation

page_text: since there is no lateral disturbance of the water to produce injurious action
upon the banks.
The accompanying Drawing represents a screw propeller constructed
according to this Invention. The propeller has two broad blades a, a, of
regular pitch, the peripheries of which are at all points equidistant from the
axis. Upon each blade at the periphery is cast or otherwise securely affixed a
rim extending backward a short distance, as shewn at b, b; and this rim is in
the form of a regular spiral strip cut from a thin cylinder, the interior diameter
of which coincides with the peripheries of the blades. If this strip were laid
flat it would be straight on the edges; but the propeller may also be con-
structed with an increasing pitch, and in that case the strip when laid flat
would have a curved form, corresponding with the increase of the pitch. As
by this construction the water will not be thrown outward by centrifugal
action, a greater pitch may be given to the blades than is usual whenever
that would be desirable.
And having now described the nature of the said Invention, and in what
manner the same is to be performed, I declare that what I claim as the said
Invention is, the construction of screw propellers with rims on the blades,
the said rims being sections of a cylinder, having a common axis with the
propeller, substantially in the manner and for the purposes set forth.
In witness whereof, I, the said Richard Archibald Brooman; havo
hereunto set my hand and scal, this Fourth day of December, One
thousand eight hundred and fifty-four.
R. A. BRUOMAN. (L.B.)