T. A. EDISON. AUTOMATIC-TELEGRAPHY.

Patented Feb. 22, 1876.

Y RRYARMYER RRSEW ER 3S: E QQH FFI THOMAS A. EDISON, OF NEWARK, NEW JERSEY, ASSIGNOR TO HIMSELF AND GEORGE HARRINGTON, OF WASHINGTON, D. G.

IMPROVEMENT m AUTOMATIC TELEGRAPHY.

Specification forming part of Letters Patent No. 173,758, dated February 22, 1876; application filed January 15, 1875.-

Newark, in the county of Essex and State of New Jersey, have invented an Improvement in Automatic Telegraphs, of which the following is a specification 1 .The object of this invention is to produce block characters on chemical paper by aggregation of dots, and the transmission is efl'ected by a strip of perforated paper, the perforations being grouped together to form the block letter, as in my Patent No. 151,209.

I make use of four lines of pertbrations in composing the block letter, four rollers or stylus-points at both the receiving and transmitting stations. The first pair of rollers are in advance of the second pair, and one roller= of one pair' and another of the other pair are connected, and act with a positive current over the lines, and the other rollers of the other pair act with the negative current. This arrangement produces the record of the letters properly in succession in dots, forming block characters; but there are also produced some false dots between the letters, that are steppedout or obliterated by hand at the receivingstation, so that only the true characters remain visible. 7 I

In the annexed diagram the receiving drums a and b, at the transmitting and receiving station, respectively, are operated as usual, and draw along the strips of perforated paper c and chemical paper (I.-

The receiving stylus-points 1 and 3 are connected to the earth -wire 0, and the stylus points 2 and 4 are connected to the line f, and between-the line f and ground-wire c a small eleetro-niagnet,h, is placed, so as to actto neutralize the static or induced current in the line, as explained in my Patent N 0. 135,531.

At the transmitting-station the rollers 5 and 7 are connected to the positive pole of the battery I, and the rollers 6 and 8 to the negative pole, the. line-wire f being connected to the center of the battery, and the drum' a being connected, to the earth.

Suppose, now, that four transverse perforations, composing theletter I, pass under the rollers 5 6 7 8; the roller 5 first sends a negative pulsation through the ground through 1 and 3, marking the paper, returning by 2 andi to the line, and these points 1 and 3 will mark, but 2 and 4, beingqa negative return current, will not. N0.-1'is a true mark, but 3 is a false mark, that is obliterated, as illustrated in Fig. 2. The roller 6 now sends a positive current over the line,.whieh goes by 2 and 4, and leaves by 3 and 1. The mark 4 is false, and is obliterated. The pulsation sent by 7 is next negative, and goes by 1 and 3, and mark 3 is true, but 1 is false, and is obliterated, and then the roller 8 sends a positive current over the line by 2 and 4, returning by 1 and 3. The mark 4 is the true one, and 2 is the false one; but, in consequence of arranging the pairs of points in advance of each other, as shown, thefalse marks are brought together between the respective characters, while the characters themselves stand out true and correct.

The character will be made by the pulsations as indicated, according to the arrangement of the perforations representing that character, and the falsemarks, being between the character, are blotted out by a boy. or attendant after the strip of paper is received from the machine, so as only to leave the characters themselves apparent between the blots, as illustrated in Fig. 2.

I claimas my invention .Four transmitting stylus-points or rollers, connected in pairs to the positive and the negative of a battery, to which the line-wire is united at the center, in combination with two stylus-points connected to the line and two to the earth at the receiving-station, the

parts being arranged and operated as set forth.

Signed by me this 7th day of August, 1874.

THOMAS A. EDISON. Witnesses:

GEO. '1. PINCKNEY, CHAS. H. SMITH.