IMPROVEMENTS IN THE CONSERTONION OF ARTIFICIAL LEGS
Year: 1852

page_text: LETTERS PATENT to Benjamin Mitchell, of Romsey, in the County
of Hants, Builder, for the Invention of "IMPROVEMENTS IN THE
CONSERTONION OF ARTIFICIAL LEGS"
Sealed the 5th April 1853, and dated the 5th October 1852.
PROVISIONAL SPECIFICATION left by the said Benjamin Mit-
chell at the Office of the Commissioners of Patents, with his
Petition, on the 5th October 1852.
I, BENJAMIN MITCHELL, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN THE CONSTRUCTION OF ARTIFICIAL LEGS"
to be as follows:-
The object of this Invention is to construct the joints of an artificial
limb in such a manner that the wearer may with facility perform the
various motions required in walking, kneeling, riding, and other actions..
This object is effected principally by the use of a spring or springs,
which I term muscular spring cords; these muscular springs lead from
the hip joint through the knee, to the leg, and thereby cause the
necessary actions.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Benjamin Mitchell in the Great Seal Patent
Office, on the 5th April 1853.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I,
BENJAMIN MITCHELL, of Romsey, in the County of Hants, Builder, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fifth day of October, in the
year of our Lord One thousand eight hundred and fifty-two, in the
sixteenth year of Her reign, did, for Herself, Her heirs and succes-
sors, give and grant unto me, the said Benjamin Mitchell, Her special
license that I, the said Benjamin Mitchell, my executors, administra-
tors, and assigns, or such others as I, the said Benjamin Mitchell, 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 yend, within the United Kingdom of Great Britain and
Ireland, the Channel Islands, and Isle of Man, an Invention for
"IMPROVEMENTS IN THE CONSTRUCTION OF ARTIFICIAL LEGS," upon the
condition (amongst others) that I, the said Benjamin Mitchell, 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 months
'next and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Benjamin Mitchell, 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 Drawings
hereunto annexed, and to, the letters and figures marked thereon (that
is to say):
This Invention, relates to a novel construction of artificial leg, the
principal object being, by means of the movement of the thigh, whether
in walking or when sitting down or rising from a seat, to communicate

page_text: natural knee.!
pending of ne
In carrying out this object. I construct. the limb, by. preference, of
thin sheet metal, and form the part below the knee in any ordinary
manner, giving the foot such elasticity in the tread as may be required.
To this lower part I joint two curved plates, which are fitted..to
embrace the stump of the amputated member; and, besides the rigid
connection formed between these parts by the joint pins, I connect the
upper and lower parts together by elastic straps; which are secured to a
belt passing round, the waist of the wearer of the artificial limb, 'and
are capable of acting, alternately, according to the motions of the hip
joint, so as to straighten or. bend the limb.
The manner of carrying out this Invention is shewn in the ac-
companying Drawing, wherein Fig. 1, is; a partial elevation of the
improved construction of limb forming the subject of the present
Invention; and. Fig: 2, is. a vertical section of the same. a, a, is
the lower part of the limb; and b, b, the two curved plates, which
are connected at c, to each other.and. to the part a. These plates
bb, are each provided with a rest d.. over which is placed a cusliion
to receive. the stump, of the amputated member, and the plates are
bound-tightly to- the stump by means of a strap c. The front part
of the curved plate is made hollow. to receive a strap f, which
passes down from the belt round the body of the wearer of the arti-
ficial limb through this hollow channel, and is attached to the lower
part a, of the limb near the upper part of the, calf. The lower
end of the plate 6, is shaped to fit the part a, and to work therein
like a ball and socket attachment, and thus the appearance of the
natural knee, whether the limb be bent or straightened, is attained.
Near the point where the strap f, is attached to the part a, a second
strap y, is also secured. This strap passes upwards (on the opposite
side of the joint c, to that of the strap f) through a slot cut in the
back of the plate 6, and thence to the belt before mentioned. When,
therefore, the party wearing the limb commences the movement neces-
sary to scat himself, that is, to bring the thigh to a horizontal line,
the strap g, will be drawn to tension, and thereby the point 1, of the

page_text: assume
part a, (which is the point of attachment of the straps) will be caused
to approach the point 2, of the part b, (which is the bearing point of
the strap g,) until the upper and lower parts of the limb the
position with respect to each other as indicated by the dotted lines of
Fig. 2, the strap f, being simultaneously slackened by the nearer
approach of the forward part of the belt towards the knee to allow of
this action. As soon, however, as the wearer of the limb begins to rise,
a corresponding slacking of the strap g, and taking up of the slack of
the strap f, will take place, and thus the limb will be again drawn out
of its bent into its straight position. It will thus be understood that,
instead of employing internal springs (as in the ordinary construction
of artificial limbs) to keep the leg straight, the effect of which is to
necessitate the expenditure of some considerable power (to counteract
the pressure of the springs) before the knee can be bent to suit the
sitting posture, the proper action of the knee is rendered compulsory and
answers to the action of the hip joint, which action causes the tension
of the one strap while it slackens the other to allow of that tension
being made serviceable for moving the limb.
Having thus described the nature of my Invention, and 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 as of my Invention
of improvements in the construction of artificial legs the mode of con-
trolling the action of the limb by the action of the hip joint, as above
explained.
In witness whereof, I, the said Benjamin Mitchell, have hereunto
set my hand and seal, this Fifth day of April, One thousand
aight hundred and fifty three
Witness,
J. W. MOFFATT,
66, Chancery Lanc.
BENJAMIN MITCHELL. (L.S.)