In 1829 Morse made a second visit to Europe, where he was warmly welcomed and honored by the Royal Academy. During three years or more he lived in continental cities, studying the Louvre in Paris and making of the famous gallery an exhibition picture which contained about fifty miniatures of the works in that collection. In November, 1832, he was back again in New York, with high hopes as to his future. Allston, writing to Dunlap in 1834, said: "I rejoice to hear your report of Morse's advance in his art. I know what is in him perhaps better than anyone else. If he will only bring out all that is there he will show parts that many now do not dream of." For several years the thoughts of the artist Morse had been busy with a matter wholly outside of his chosen domain. Some lectures on electro-magnetism by his intimate friend, Judge Freeman Dana, given at the Athenæum while Morse was also lecturing there on the fine arts, had greatly interested him in the subject, and he learned much in conversation with Dana. While on his second visit to Europe Morse made himself acquainted with the labors of scientific men in their endeavors to communicate intelligence between far-distant places by means of electro-magnetism, and he saw an electro-magnet signalling instrument in operation. He knew that so early as 1649 a Jesuit priest had prophesied an electric telegraph, and that for half a century or more students had partially succeeded in attempts of this kind. But no practical telegraph had yet been invented. In 1774 Le Sage made an electro-signalling instrument with twenty-four wires, one for each letter of the alphabet. In 1825 Sturgeon invented an electro-magnet. In 1830 Professor Henry increased the magnetic force that Morse afterward used.