A NEW OR IMPROVED PROPELLER FOR SHIPS AND OTHER VESSELS
Year: 1879

page_text: LETTERS PATENT to John Evelyn Liardet, of No. 4, Brakespear's Road,
Wickham Park, Brockley, in the County of Kent, for the Invention of
"A NEW OR IMPROVED PROPELLER FOR SHIPS AND OTHER VESSELS."
Sealed the 7th May 1880, and dated the 10th November 1879.
PROVISIONAL SPECIFICATION left by the said John Evelyn Liardet at the
Office of the Commissioners of Patents on the 10th November 1879.
JOHN EVELYN LIARDET, of No. 4, Brakespear's Road, Wickham Park, Brockley,
in the County of Kent. "A NEW OR IMPROVED PROPELLER FOR SHIPS AND
OTHER VESSELS.".
The object of my Invention is the construction of a propeller which (amongst
others) shall possess the following advantages:-Firstly, that it shall take a better
hold or grip of the water so as to give more propelling power; secondly, that
there shall be less "slip; " thirdly, that from its form or configuration, it shall pass
off the water instead of dragging and towing churned water; fourthly, that it
shall give greater speed than the screw propellers heretofore in use; and, fifthly,
that there shall be a great diminution of the unpleasant and destructive vibration
attending the use of the ordinary propellers.
My Invention consists as follows:-A boss, which in comparison with those
heretofore in use is elongated, is cast with or has attached to it four double blades.
These double blades are so curved or disposed that between them is left an
The root of the
opening which is somewhat elliptical or pear shaped in form.
blades is disposed spirally around the boss (so far as its length permits), and to
the eye the arrangement will appear like two propellers set opposite to each other;
the leading edge of the former being the following or trailing edge in the latter.
The water passes from one blade to the other, whilst the elliptical or pear shaped
spaces destroy any vacuum that might otherwise exist, and thereby lessen the
efficiency of the propeller.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Evelyn Liardet in the Great Seal Patent Office on the 10th May
1880.
JOHN EVELYN LIARDET, of No. 4, Brakespear's Road, Wickham Park, Brockley,
in the County of Kent. "A NEW OR IMPROVED PROPELLER FOR SHIPS AND
OTHER VESSELS."
The objects proposed to be effected by improved construction of propeller are
as follows:
Firstly, that a propeller so constructed shall take a better hold or grip of the
water so as to give more propelling power than any heretofore in use.
Secondly, that there shall be less slip.
Thirdly, that from its form or configuration it shall pass off the water instead of
dragging and towing churned water.
Fourthly, that it shall give greater speed than the screw propellers heretofore in
use and with a smaller number of revolutions, and consequently less wear and tear
to the engines and ship, and a diminution in the consumption of fuel; and—
Fifthly, that there shall be a great diminution of the unpleasant and destructive
vibration attending the use of ordinary propellers.
My Invention consists as follows:-
A boss, which by comparison with those heretofore in use may be described as
elongated, is cast with or has attached to it two double blades. These blades are so
formed, curved, configured, and disposed, that between them is left an opening
which is somewhat elliptical or pear shaped in form. The root of the blades is
disposed spirally around the boss (so far as its length permits), and to the eye the
arrangement will appear like two propellers opposite to each other; the leading
edge of the former being the following or trailing edge of the latter.
The water passes from one portion of the blade to the other, whilst the elliptical
or pear shaped spaces destroy any vacuum that might otherwise exist, and thereby
lessen the efficiency of the propeller.
The number of the blades may in some cases be increased if desirable, whilst the
features of my Invention are maintained.
In order that the nature of my Invention and the manner in which the same is
to be effected may be particularly described and ascertained, this Specification is
accompanied by a sheet of Drawings having figures and letters of reference marked
thereupon, the like letter being used to denote a similar or corresponding part in
each Figure.
In these Drawings Figure 1 is an elevation of my improved double propeller, in
which is shown the position of the elliptical or pear shaped openings or spaces
hereinabove mentioned as being left by the relative positions of the double blades.
These openings are marked A. Figure 2 is a plan of Figure 1. The boss is marked
B, the blades C, C¹, and the screw or propeller shaft D. Figure 7 shows the means I
prefer of securing the blades in the boss B, the boss being flanged as shown, the
root of blade C entering between two flanges and secured by screws or rivets, their
heads being countersunk for that purpose.
I may vary the size of the openings A by altering the relative positions of the
double blades C, C, and for this purpose I prefer to make the boss in two parts, as
shown on the Drawing. Figure 3 shows another view of my improved propeller in
which the position of the blades is thus varied. It is a view looking "aft."
Figure 5 is a view of the same looking "forward." Figure 4 is a plan of Figure 3,
and Figure 6 a plan of Figure 5.
Having now particularly described and ascertained the nature of my said
Invention and the manner in which the same is to be carried into effect, I wish it

page_text: to be distinctly understood that what I claim and desire to secure by the herein-
before in part recited Letters Patent is, the construction and use of double
propellers of the form or shape, and for the purpose or purposes all, as in this
Specification described and in the accompany Drawings illustrated.
In witness whereof, I, the said John Evelyn Liardet, have hereunto set my
hand and seal, this Seventh day, of May, in the year of our Lord One
thousand eight hundred and eighty.
J. EVELYN LIARDET. (LS.)