Page:Heroes of the telegraph (IA cu31924031222494).djvu/58

 electricity sensible at the far end of the line were considered. The spark might pierce a band of travelling paper, as Professor Day had mentioned years before; it might decompose a chemical solution, and leave a stain to mark its passage, as tried by Mr. Dyar in 1827; Or it could excite an electro-magnet, which, by attracting a piece of soft iron, would inscribe the passage with a pen or pencil. The signals could be made by very short currents or jets of electricity, according to a settled code. Thus a certain number of jets could represent a corresponding numeral, and the numeral would, in its turn, represent a word in the language. To decipher the message, a special code-book or dictionary would be required. In order to transmit the currents through the line, he devised a mechanical sender, in which the circuit would be interrupted by a series of types carried on a port-rule or composing-stick, which travelled at a uniform speed. Each type would have a certain number of teeth or projections on its upper face, and as it was passed through a gap in the circuit the teeth would make or break the current. At the other end of the line the currents thus transmitted would excite the electro-magnet, actuate the pencil, and draw a zig-zag line on the paper, every angle being a distinct signal, and the groups of signals representing a word in the code.

During the voyage of six weeks the artist jotted his crude ideas in his sketch-book, which afterwards became a testimony to their date. That he cherished hopes of his invention may be gathered from his words on landing, 'Well, Captain Pell, should you ever hear of the telegraph one of these days as the wonder of the world, remember the discovery was made on the good ship Sully.'

Soon after his return his brothers gave him a room on the fifth floor of a house at the corner of Nassau