1880.] ou {he Ti'lrr/rajJtir Achievements of Wheafstonc. 301 



springs ; and when tlio actual mcclianism of the sending portion of 

 the alphabetical instrument was reflected on a screen tlie i)rin- 

 ciplc of the instrument was clear.) I have shown you the primi- 

 tive instrument of 1810, and its improved though cundn-ous form of 

 1858 ; and here is its elegant representative of 1880, which is joined 

 up to a wire between this room and the Central Telegraph Station, 

 and by which we will have a little conversation. There is scarcely 

 a portion of this instrument that is not an imj^rovement on the earlier 

 forms, and some of the improvements have j^assed through many 

 stages before reaching their present perfection. The original prin- 

 ciide ado2)ted by Wheatstone remains, but the teachings of 2)ractice 

 and observation showed practical defects which have been removed, 

 and so brought the instrument to what you now see. (Several items 

 of general news were received on the alphabetical instrument from 

 the Central Station.) While this instrument is slow, it is sure, and, 

 comparing its pioneer of 1840 to a cart-horse, may be said to be a fine 

 racer. It is very useful for private j^urposes or at outlying offices 

 where little business is done ; and many thousands of them are so 

 employed. 



Having succeeded so far in obtaining simplicity, Wheatstone 

 turned his attention to the practicability of sending telegraphic 

 signals by machinery without the aid of the hand in manipulation, 

 and thus increasing the capacity of wires for carrying messages. 

 Bain in England, Siemens in Germany, and others had been working 

 in a similar field, and in 1858 the genius of Wheatstone, combined 

 with the mechanical ingenuity of Mr. Stroh, developed an entirely new 

 system of automatic telegraphy on the principle of the Jacquard loom. 

 A 2)aper ribbon was passed through a piece of mechanism consisting 

 of three keys with cutting j)^^iiches, which, when pressed on the 

 pajier, perforated it according to the key depressed. Tlic centre 

 key cut a continuous row of holes, which were used to j^ush forward 

 the paper. The left-hand key cut two holes directly opposite each 

 other, and represented the left-hand beat of a needle, or the dot of the 

 Morse alphabet. The right-hand key cut two holes, one above and 

 one below the middle row, but in a slanting direction from left to 

 right, and represented the right-hand beat of a needle, or the dash of 

 the Morse alphabet. The paper so perforated was then 2)assed 

 through the automatic transmitter, the action of which I can, jierhaps, 

 make clear by the use of a model. 



Wheatstone's automatic instrument transmits a succession of 

 currents of electricity in opposite directions, and if no paper were 

 interposed to prevent these currents going exce2)t at the pr()2)er time, 

 this succession of currents would be continually transmitted. (A 

 model of the transmitter was explained in detail.) So that when no 

 holes present themselves to the rocking prongs for the currents to 

 pass through, nothing goes to line ; but if two holes, representing a 

 dot, present themselves, then a current passes, and a dot is in'oduced 

 at the receiver; and so, if the holes re2)rcsenting a dash admit the 



