358 



HENRY AND THE TELEGRAPH. 



similar order of permutations. The two symbols — tlic single dot or period (.), and the 

 double dot or colon (:), — are also employed for the same purpose. * 



In the following table are displayed several examples of bi-signal alphabets, chrono- 

 logically arranged.! In the first column, the two symbols "a" and " b," and in the 

 second column the two symbols "1" and "2," may stand for dots, lines, colors, bells, 

 or any other distinctions of sight or sound, as indicated by Bacon and by Rees. In 

 the third column is exhibited the notation of an acoustic alphabet devised by Mr. James 

 Swaim, of Philadelphia, and published in 1829, in a pamphlet entitled " The Mural 

 Diagraph, or the Art of Conversing though a Wall." In this scheme (sometimes 

 designated the 2)rlson alphabet), the symbol "t" signifies an audible tap or knock, 

 and the "s" an audible scratch, t In the next three columns, the two symbols "r" 

 and "1" represent a movement of a galvanometer needle to the right and to the left. 

 In the last three columns, the symbols "s" and "1" represent a short mark or dot, 

 and a long mark or dash. 



*Rees' Cydopcedia, a^oI. viii, art. "Cipher." 



tOf two early aljdiabets for the electric telegraph, — that of Lomond in 1787, and that 

 of Dyar in 1828, no records ap]>oar to exist. A plan was suggested by Henry at Al- 

 bany in 1831 or 1.S32, for indicating letters on a bell bv the number of their position in 

 the alphabet: "a"byl, "b" by 2, "c"by 3, &c. 'Thus the words "come back" 

 would bo represented by the following taps ; 3-15-13-5 — 2-1-3-11 ; the word " electro- 

 magnet," by 5-12-.5-3-20-18-15— 13-l'-7-14-.5-20. The cijiher or zero oc(^urring at the 

 10th letter "j," and at the 20tli letter " t" would be indicated by a rapid rattle of the 

 bell. It does not appear however that this alphabet was actually employed, unless 

 perhaps experimentally. 



t The Mural Diar/raph, etc. " Through the wall they are content [ To whisper, at the 

 which let no man wonder." Midsuuuner Night's DreJim, v. i. By Jamos Swaim. 16- 

 mo. 24 pages. Philadel]>liia. Printed by Clark & Rascr. 1829. pj). 13, 14. The 

 signs were used numerically ; and beyond "26" (the letters of the alphabet) were ap- 

 plied to a numbered vocabulary. 



