Improvements in Rubber Erasers and the Method of Utilizing India- rubber for Erasive Purposes.
Year: 1890

page_text: Date of Application, 30th Dec., 1890-Accepted, 21st Feb., 1891
COMPLETE SPECIFICATION.
Improvements in Rubber Erasers and the Method of Utilizing India-
rubber for Erasive Purposes.
I, HERBERT JOHN ALLISON, of 52, Chancery Lane, London, in the County of
Middlesex, Patent Agent, do hereby declare the nature of this invention, (which
has been communicated to me from abroad by William Friend, of the City of
New York, County and State of New York, United States of America, Manu-
facturer,) and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement :-
My invention relates to the use of india-rubber for the purpose of effecting
erasures of lead-pencil marks, etc., from the surface of paper, etc.
My invention consists, primarily, in the improved method of utilizing india-
rubber for such erasive purposes which comprises creating a condition of sub-
stantially uniform tension throughout the entire mass of the rubber and uniformly
supporting and permanently holding in its said tense condition said rubber mass,
throughout its entire area, fixedly, by and upon a rigid foundation; and my inven-
tion consists further in the combination with a rigid disk or plate provided at its
circumferential edge with a continuous encircling flange, of a rubber jacket which
is centrally apertured transversely, and is of normally less diameter than the flange
disk or plate, and which is adapted to correspond and fit to, and is mounted upon
the rim Hange of said disk or plate in a uniformly distended and tensioned condition
thereon; and my invention also comprises a rubber eraser which is chambered and
provided with apertures, singly or in series, in the chamber wall or walls, com-
municating from said chamber to the exterior of the eraser-body, together with,
preferably, a textile or absorbent material enclosed in said chamber.
Figure 1 is a side elevation of a rubber eraser containing my invention;
Figure 2 is a vertical central cross-section of the same;
Figure 3 is a similar section, showing a modification of my invention;
Figure 4 is a similar section of a rubber eraser, showing one form of the
chambered eraser; and
Figures 5, 6, and 7 are similar sections showing modifications in the form of my
chambered eraser.
Heretofore in fabricating india-rubber erasers, the rubber has had mixed with it
various substances such, for example, as powdered glass, emery, zinc-white, etc., in
order to give the eraser the requisite firmness or stiffness to adapt it to its use.
When a mass of india-rubber which is substantially pure is put in a condition of
tension, it becomes more or less stiff and firm, in proportion to the degree of the
tension created in the mass.
In carrying out my invention, therefore, I take the mass of substantially pure
india-rubber, which is to constitute the eraser, and I create in it a condition of
tension which is substantially equal or uniform throughout the entire mass. I then
uniformly support and permanently hold the said entire mass in said tense condition
fixedly upon a rigid foundation or support.
This may be accomplished by stretching or clamping the entire rubber mass
uniformly upon or over or around a block or piece of wood, metal or analogous
rigid substance of corresponding area and conformable outline or shape on its
supporting surface.
It is essential to my invention that the entire mass of the rubber should be
given tension, and that the entire tense mass should be uniformly supported and
permanently held fixedly upon its rigid support, as thereby a uniform stiffness
throughout the mass is established and maintained.
When the india-rubber is thus made and held tense, as set forth, the edges of the

page_text: minute cells of which the mass is composed, are exposed and rendered sharp, thereby
giving to the exposed face or faces of the mass a surface which is peculiarly
adapted to establish, effective contact with pencil and analogous marks on the paper
over and upon which the eraser is passed, and to remove or obliterate such marks
from the paper with but slight friction of the erase thereon.
When india-rubber has mixed with it the foreign substances herein before named,
for the purpose of producing rigidity, the presence of such substances tends to soil,
and often to wholly destroy the surface of the paper to which it is applied in
making erasures. By means of my invention, I am enabled to fabricate an eraser
of approximately pure india-rubber which will rapidly remove marks from a paper-
surface, and which in effecting erasures, will cause a minimum of damage to such
paper-surface.
am aware that a tubular piece of rubber has been held to place upon and
prevented from longitudinal movement or displacement on a cylindrical support by
means of an annular rib or projection on the support which distends a portion only
of the rubber tube, to wit, that portion that surrounds the rib or projection; but in
such case, only a portion of the rubber mass which constitutes the rubber tube is
initially distended, the remainder of the tube being left in normal condition, that is
to say, in a non-tensioned state, and with the tube ends unconfined, and thus free
to move on the support. Under such conditions the initial tension créated in that
portion of the rubber distended by the rib will not be permanent even in such
portion, owing to the nature and characteristics of the rubber itself, said tension
being, by molecular action in the rubber mass, gradually destroyed, or distributed
throughout the entire mass, until the initially distended portion becomes hardened
and hence useless for erasive purposes, or the entire tube assumes a practically
non-tensioned condition. I make no claim herein, broadly, therefore, to the
creation of tension in india-rubber, but I intend to make my claim to creating a
condition of substantially uniform tension throughout an entire mass of rubber and
then uniformly supporting and permanently holding, in its said tense condition, said
rubber mass, throughout its entire area, fixedly, by and upon a rigid foundation;
whereby the entire tensioned mass of the rubber is maintained in a condition wherein
the entire area of its exposed face is given the described advantages for erasive
purposes.
A is a rigid disk or plate, of suitable material, as of wood or metal, and preferably
circular in outline, as shown. The edge of the disk or plate is formed or provided
with the continuous encircling and preferably tapering flange a.
B is a jacket of india-rubber which corresponds interiorally, and in general
outline to the flange a of the plate A. The jacket is centrally apertured,
laterally and transversely at b, as shown, and is made of such size that it will,
in its normal condition, be of less diameter than the flanged plate upon which it is
to be mounted.
The jacket B is mounted upon the plate A, on the flange a thereof, as shown,
and this may be accomplished by distending the central aperture 6 in the jacket
and inserting the plate edgewise through said distended aperture, whereupon,
when the plate is thus inserted, the jacket will retract upon and fit to the flange a
of the plate.
The plate A may have the circumferential shoulders a', where the flange meets
the central portion or body of the plate; and, in such case, the rims of the central
aperture of the jacket may be made to fit to and against said shoulders, as shown
in Figure 2; or, the sides of the flange may meet the sides of the plate directly, at
angle, as shown in Figure 3, when the rims of the central aperture in the jacket
may be desirably brought to a thin edge at the juncture of the flange and plate
sides, as shown at 6', Figure 3.
The rim of the flange may be given a rounded edge, as shown in Figure 2, or
may be given an angular or sharp edge, as shown in Figure 3.
By means of my invention, I not only seat the rubber firmly to the edge of its
supporting plate, but I also create and maintain a uniform tension throughout the

page_text: entire extent of the jacket, thereby imparting an increased firmness and better
erasive properties to the rubber itself, while I am, at the same time enabled to
employ an approximately pure rubber, free from foreign substances, as the eraser-
surface. Furthermore, I provide not only an edge to the eraser, at its rim,
adapted for use upon a closely written or lined page or drawing, but also, flattened
tensioned surfaces, as at 2, on the sides of the jacket, constituting broad erasive
surfaces.
In carrying out a feature of my invention, I form or constitute a chamber
in the body of the eraser, and I provide an aperture, or apertures, in the
chamber wall, or walls, and communicating from said chamber to the exterior
of the eraser-body.
In the body of the eraser is constituted the chamber C. The chamber may be
constituted wholly in and enclosed by the india-rubber body of the eraser as
illustrated in Figure 4 by casting a similar or corresponding recess in one face of
each of two halves or disks c and c', of india-rubber, and then bringing the said
recessed faces of the disks or halves together and connecting the disks at their
united edges, as shown in said Figure 4; or, the said chamber may be formed by
recessing, as at ² Figure 6, a face of the india-rubber body of the eraser, and
closing the mouth of the recess by a plate or lid e³, which may be held in place by
a rivet e passed transversely through the plate and eraser-body or, it may be
desirable to constitute the eraser of a rubber rim-piece D clamped between two
plates & which are held together by a rivet d', as shown in Figure 7, the chamber C
being constituted by the space enclosed by the rim-piece and plates.
The eraser may be formed of a block or holder E which is desirably of some
rigid material, such as wood or metal. The block has constituted in it a chamber C,
and this may be effected by uniting on their recessed faces two dishing disks or
plates of metal e, e¹, by means of an over-turned or folded rim-flange e³, as shown in
Figure 5.
Ate are apertures, one or more, which are formed in the wall, or walls, of the
chamber C, and which communicate from said chamber to the exterior of the
eraser-body, as shown.
I have shown in the drawings a circular eraser; but it is evident that the form
of the eraser body may be varied from that illustrated without departure from the
described essential features of my invention.
I find it desirable to provide a number of the apertures e² in the chamber wall,
and to group said apertures at or about the centre of the eraser-body in one side
wall only of the body, as shown. When the apertures are thus constituted and
arranged they may be covered by the thumb or fingers of the user when the eraser
is grasped in the hand for use in erasing, and the escape of the contents of the
chamber, as hereinafter set forth, be thus prevented, during the use of the
eraser; while, when the eraser is not in use it may lie or rest upon its unperforated
side.
I prefer to constitute the plate c³ and d, of some rigid material, such as wood,
metal, celluloid, etc., as a desirable holder is thus given to the eraser..
Within the described chamber C there may be enclosed a sack or piece of felt or
cloth, containing or saturated with a perfume, the odour of which will escape
through the apertures e² and may impart a scent to stationery with which the eraser
is in proximity, as, for example, in a writing-case or desk.
Having now particularly described and ascertained the nature of my inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:
1. The method of utilizing india-rubber for erasive purposes, which consists in
creating a condition of substantially uniform tension throughout the entire mass of
the rubber, and uniformly supporting and permanently holding, in its said tense
condition, said rubber mass, throughout its entire area, fixedly, by and upon a rigid
foundation, substantially as and for the purpose set forth.

page_text: 2. In a rubber eraser, the combination with a rigid disk or plate, provided at its
circumferential edge with a continuous encircling Hange, of a rubber jacket which
is centrally apertured transversely and is of normally less diameter than the disk or
plate, and which is adapted to correspond and fit to and is mounted upon the edge
flange of said disk or plate in a uniformly distended and tensioned condition thereon,
substantially as and for the purpose set forth.
3. A rubber eraser which is chambered and is provided with apertures, singly or
in series, in a wall of said chamber, and communicating from said chamber to the
exterior of the eraser body, together with a textile or absorbent material enclosed
in said chamber, substantially as and for the purpose set forth.
4. A rubber eraser composed of two recessed rubber plates or disks, united flat-
wise at their recessed sides to constitute a chamber within the eraser, and one or
both of said plates being provided with apertures, singly or in series, communi-
cating from said chamber to the exterior of the eraser body, substantially as
set forth.
5. A rubber eraser composed of an india-rubber plate having a recess in a face
thereof, a lid which closes the mouth of said recess, and apertures, one or more,
provided in a wall of said chamber and communicating therefrom to the exterior of
the eraser-body, substantially as and for the purpose set forth.
6. A rubber eraser composed of an india-rubber rim, plates between which said
rim is clamped and held, and apertures, one or more, in said plates, and communi-
cating from the chamber, enclosed by said rim and plates, with the exterior of the
eraser, substantially as and for the purpose set forth.
7. A rubber eraser composed of a chambered block or holder provided with
apertures, one or more, in a wall of said chamber and communicating from said
chamber with the exterior of the block, and a piece of india-rubber mounted upon
said block, substantially as and for the purpose set forth.
8. In a rubber eraser having a chambered holder or body supporting a piece of
india-rubber mounted thereon, apertures, one or more, provided in and located at or
about the central portion of a side of said holder or body constituting a wall of the
chamber therein, and communicating from said chamber to the exterior of said
holder or body, substantially as and for the purpose set forth.
Dated this 30th day of December 1890
ALLISON BROS.,
Agents for the Applicant.