IMPROVEMENTS IN CASTORS
Year: 1859

page_text: LETTERS PATENT to Thomas Bird, of the City of Manchester, in the
County of Lancaster, Engineer, for the Invention of "IMPROVEMENTS IN
CASTORS."
Sealed the 14th February 1860, and dated the 26th August 1859.
PROVISIONAL SPECIFICATION left by the said Thomas Bird at the
Office of the Commissioners of Patents, with his Petition, on the 26th
August 1859.
I, THOMAS BIRD, of the City of Manchester, in the County of Lancaster,
Engineer, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN CASTORS," to be as follows:-
In a plate of metal or other material of any suitable size or shape according
to the size or shape of the article to which the castor is to be fixed, I make a
circular hole, the said hole to vary in size according to the size of the ball to
be used. To the said plate I attach a cap, or skeleton cap to prevent the ball
falling from its place; the said plate having a piece of india-rubber, leather,
or other suitable material between it and the piece of furniture to prevent
noise; being screwed or otherwise fastened to the leg of a table, pianoforte, or
other article, the ball will revolve in contact with the edges of the hole in the
plate, and will act without the cap as long as the pressure acts direct upon it,
the edge or edges of the said hole being the propelling point or points of the

page_text: ball. Therefore, I claim the use of the ball and plate, either with or without a
cap, and I do not confine myself to a circular hole, as the ball will revolve in
other shaped holes, but not with equal freedom. It is evident, that instead
of making a hole in the plate, I can raise a rim, edges, or points on it, which
will answer the same purpose.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Thomas Bird in the Great Seal Patent Office on the
25th February 1860.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
BIRD, of the City of Manchester, in the County of Lancaster, Engineer, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-sixth day of August, in the year of our Lord
One thousand eight hundred and fifty-nine, in the twenty-third year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Thomas Bird, Her special licence that I, the said Thomas Bird, my
executors, administrators, and assigns, or such others as I, the said Thomas
Bird, 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
CASTORS," upon the condition (amongst others) that I, the said Thomas
Bird, by an instrument in writing under my hand and seal, should par-
ticularly 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 imme-
diately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Thomas Bird, do hereby declare the
nature of my said Invention, and the manner in which the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement (that is to say) :-
I employ a plate of metal or other material of any suitable size or shape,
according to the form and dimensions of the article to which the castor is to
be fixed. In the plate is a circular hole in which the ball is placed, which
hole varies in diameter according to the size of the ball to be used, and to the

page_text: plate is attached a skeleton, plain, or ornamental cap, for the purpose of
preventing the removal of the ball from its place when the piece of furniture.
or other article is raised. When the plate is screwed or otherwise fastened to.
the leg of a table, pianoforte, or other article, and the hole placed upon the ball,
the latter will revolve in contact with the edges of the hole when the article
is moved, and will act without the cap as long as the pressure is direct upon
it, the edge or edges of the hole being the propelling point or points of the
ball. Instead of a circular hole in the plate it may be made triangular,
square, or of any other shaped figure, so that the ball may rest against a
number of points; and also instead of making a hole in the plate, I can raise
a rim, edges, or points upon it, against which the ball will act, and answer the
same purpose as the circular hole.
These improvements will be clearly understood by referring to the Figures
and letters on the accompanying Sheet of Drawings, in which Figs. 1 and 2
are external elevations of two castors resting vertically, and furnished with
caps or guards; Figs. 3 and 4 are external elevations of the same without the
caps or guards; Figs. 5 and 6 are sectional elevations, shewing the edges of
the plates and their points of contact; Figs. 7 and 8 are plans of the plates
and balls, each ball resting in the edge of a round hole or point of contact;
Fig. 9 is an external elevation of a castor having a socket; Fig. 10, a plan of
the same; and Fig. 11 represents a plate having a square hole for forming
the edges with which the ball is in contact. The frame, cap, or guard a of
the castor is in one piece, united to the plate 6 by an external and internal
screw c and d, the plate 6 being the propeller, which bears or rests upon the
sphere or balle at or about one-sixth of the circumference, as shewn by the
dotted lines f. The sphere or ball fits loosely in the edge or circular line of
contact 9, which thereby becomes the fulcrum, so that the sphere or ball may
The frame, cap, or
be able to move in any direction with ease and freedom.
guard has no weight to sustain, but merely prevents the ball or sphere from
falling or being removed from its position. In my improved castor I make
the sphere or ball of glass, and the plate of cast iron, having a hole through it,
or a rim projecting from it, forming either points, edges, or a hole, thus
making it a spherical insulator peculiarly applicable to pianofortes and some
other musical instruments. The castors can run in any direction with freedom
and ease, thus being very suitable for all kinds of moveable furniture and
similar purposes. The balls or spheres may.also be made of porcelain, metal,
or any other suitable substance or composition, and the plates may also be
formed of any suitable metal or material. When force is applied to the article
to which the castor is attached, a reaction commences at 9, which may be

page_text: in
considered the moving power of a lever, shewn by the dotted lines f, having
its fulcrum or propelling point at h, representing the sixth part, or thereabouts,
of a ball or sphere, which leverage causes it to oscillate or rotate on its edges
or points in endless changes of position, and allowing the sphere or ball to run
any direction with ease and steadiness. It is important to maintain a just
proportion between the size of the ball and the hole or rim, for if the edges
are too small the ball will run off them, and if the circumference of the hole
or rim be too large, there will be so much hold upon the ball as to prevent its
turning. I may here remark, that although in Fig. 11 I shew a square hole
or rim against which the ball or sphere works, the form may be varied to any
desired extent, so as to give any number of points of resistance.
Having thus fully described the nature of my said Invention, and the
manner in which the same is to be performed, I desire it to be distinctly
understood that I do not claim the exclusive use of balls or spheres for
castors, nor any particular form of cap or skeleton cap to hold or sustain the
same; but I claim the construction of castors with balls or spheres working
loosely on the edges of round, square, or other shaped holes or edges made in
plates, as herein described and illustrated in the accompanying Sheet of
Drawings.
In witness whereof, I, the said Thomas Bird, have hereunto set my
hand and seal, this Twenty-third day of February, in the year of our
Lord One thousand eight hundred and sixty.
Signed, sealed; and delivered by the
within-named Thomas Bird, in
the presence of
E. J. HUGHES, Patent Agent,
Manchester.
THOMAS BIRD. (LS.)