Professor Jeremiah Day had taught Morse at Yale that the electric spark might be made to pierce a band of unrolling paper. Harrison Gray Dyar, of New York, in 1827, had shown that the spark would decompose a chemical solution and so leave a stain as a mark, and it was known that it would excite an electro-magnet, which would move a piece of soft iron, and that if a pencil were attached to this a mark would be made on paper. Therefore Morse knew that if he devised his alphabet he had only to choose the best method of indicating the dots and dashes by the current. The voyage from Havre to New York occupied six weeks, and during the greater part of this time he was busy working out a mechanical sender which would serve to break the electric current by a series of types set on a stick which should travel at an even rate of speed. The teeth of the type would complete the circuit or would break the current as they passed, and so send the letters. At the receiving end of the line the current as it was sent would excite the electro-magnet, which would be attached to a pencil, and so make a mark, and each mark would represent one of the symbols that were to stand for letters. He worked day and night over these first plans, and after a few days showed his notes to Mr. William C. Rives, a passenger, who had been the United States Minister to France. Mr. Rives made various criticisms, and Morse took these up in turn, and after long study overcame each one, so that by the end of the voyage he felt that he had worked out a practical method of making the electric current send and receive messages. At a later date a contest arose as to the respective claims of Samuel Morse and Dr. Jackson to be considered the inventor of the recording telegraph, and the evidence of their fellow passengers on board the _Sully_ was given in great detail. From all that was then said it would appear that Dr. Jackson knew quite as much, if not more, about the properties of electro-magnetism than Morse did, but that he was of a speculative turn of mind, whereas Morse was practical, and capable of reducing the other’s theories to a working basis. The note-books he submitted, and which were well remembered by many of his fellow voyagers, showed the various combinations of dots, lines, and spaces with which he was constructing an alphabet, and also the crude diagrams of the recording instrument which should mark the dots and lines on a rolling piece of paper. Captain Pell, in command of the _Sully_, testified later, that as the packet came into port Morse said to him, “Well, Captain, should you hear of the telegraph one of these days as the wonder of the world, remember that the discovery was made on board the good ship _Sully_.” The times were ripe for his great invention, and although other men, abler scientists and students, had foreseen the possibilities of such a system, it was Morse who determined to put it into practice.