US570797A - Blackboard-rubber - Google Patents

Description

(No Model.)

G. E. GREGORY. BLAGKBOARD RUBBER.

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UNITED STATES PATENT OFFICE.

CHARLES EZRA GREGORY, OE NASHVILLE, TENNESSEE.V

.BLACKBOARD-RUBBER.

SPECIFICATION forming part of Letters Patent No. 570,797, dated November 3, 1896.

Application filed March 9, 1896.

To @ZZ whom it may concern:

Be it known that I, CHARLES EZEA GREG- ORY, a citizen of the United States, residing at Nashville, in the county of Davidson and State of Tennessee, have invented certain new and usefullmprovements in Blackboard- Rubbers; and l do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

The object of my said invention is to provide an eraser for blackboards, or a blackboard-rubber, which, while being very efficient for the purpose, inexpensive to'manufacture, and of great durability, will also be entirely non-resonant in its character, thus providing against the common annoyance consequent upon the continual accidental dropping of erasers by users thereof upon furniture and the floor in school-rooms and other places, and the disturbance caused thereby; and it consists in various improvements in the details of construction whereby these objects are accomplished, as will be hereinafter more fully described and claimed.

Referring to the accompanying drawings, which are made a part hereof, and on which similar letters of reference indicate similar parts, Figure 1 is a perspective view of one of my improved erasers or rubbers, and Fig. 2 a cross-section through the same.

Said eraser is composed entirely of nonresonant material, preferably felt, which has been found to be very desirable for the purpose. Its back is shown as composed of two pieces A and A', stitched together, (the number of pieces is, of course, not material,)a label a, composed of soft material, as kid, soft leather, paper, or cloth, being also preferably secured thereto by the same stitches for containing the advertising-matter of the manufacturer, instructions for using, ctc. The back thus made up furnishes suiicient rigidity and stiffness for the purpose without containing any substance which will make a noise when brought into forcible contact with hard substances, such as when dropped upon a floor.

The face of the eraser is also composed of suitable non-resonant material, preferably felt, cut into strips or pieces o f suitable dimen- Serial No. 582,428. (No model.)

sions and placed face to face to make up the block desired, which is secured to said back at one of the sides composed of the edges of the strips, the opposite side forming the operating-face of the eraser or rubber. In the drawings said face is shown as composed of five strips of felt, the central one a' being of considerably greater thickness than the 6o other strips and thicker on its face than at its back to give shape to the block. On each side of said strip is a strip a2, and on the outer face of each of said strips another strip a3; but, as will be readily understood, 65 the number of strips may be greater or less, as desired, it being only essential that the rubbing-face be composed of a multiple of strips, as` will be presently described. Said several strips composing the rubbing-face of 7o the eraser are secured together by glue or adhesive material of suitable character, which is placed between their contiguous faces from their back edges to a point near their edges forming the face of the eraser, but not eX- tending entirely to said face, it being desired to leave the several edges free at this side to provide channels or recesses in the operating face to take up the crayon-dust.

The block comprising the several strips and 8o constituting the face of the eraser is secured to the back by glue or adhesive material. Said glue is indicated in the drawings by the heavy black lines and designated by the reference-letter a4. Said glue is of a character or 8 5 consistency that while it will secure the parts together with sufficient firmness yet will allow the front edges of the strips composing the rubbing-face to gradually separate under the strain of usage as they wear away, thus 9o maintaining the channels between said strips at this point for the purpose mentioned. Should such result not follow from usage in any case the desired separation could be forcibly effected, of course.

By constructing an eraser as thus described, l with its rubbing-face composed of a number of strips set with their edges forming the' operating-face and arranged so as to provide the channels in said face, an eraser is proroo vided which will, in operation, quickly `and thoroughly clean a blackboard, the dust being taken up in the channels in its face, which because of their peculiar character and for= mation, retain the same until forcibly removed, which can be readily accomplished by rapping the eraser or using a brush, or by both methods. By forming it entirely of non-resonant material it may be dropped about in the school-room or other places where used Without causing any disturbance, and because of being composed of such material and having its parts connected by a glue of the character named the eraser can be used until it is Worn entirely to the back, thus adding materially to its life, and consequently to its value, and also avoiding the danger of scratching the board and injuring it, as is often done by the use of ordinary erasers, the rubbing-surface of Which soon becomes Worn to the hard back which then comes against the board surface to its great injury.

Having thus fully described my said invention, What I claim as new, and desire to secure by Letters Patent, is-

1. A blackboard-rubber consisting of a back and several strips secured thereto to form the face, Which strips are arranged With their edges to form the rubbing-face, their contiguous faces being joined to each other by adhesive material to a point not quite to said face, whereby longitudinal Ways or channels with open ends are provided in said face to take up the chalk-dust, substantially as set forth.

2. A blackboard-rubber having a face composed of strips of material secured together to a point near their edges Which constitute the rubbing-face by an adhesive material of a character which will permit of their gradual separation, substantially as set forth.

3. A blackboard-rubber, consisting of a back of non-resonant material, and a rubbingface secured thereto by adhesive material, which rubbing-face is composed of strips of similar material arranged With their edges to form the operating-face and stuck to each other with adhesive material, substantially as set forth.

In testimony whereof I aiiix my signature in presence of two Witnesses.

XV. E. METZGER, GRACE DAWSON.

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