320. Treaty with Great Britain, 1842.--Perhaps the most important event of Tyler's administration was the signing of the Treaty of 1842 with Great Britain. Ever since the Treaty of Peace of 1783, there had been a dispute over the northeastern boundary of Maine. If the boundary had been run according to the plain meaning of the Treaty of Peace, the people of Upper Canada would have found it almost impossible to reach New Brunswick or Nova Scotia in winter. At that time of the year the St. Lawrence is frozen over, and the true northern boundary of Maine ran so near to the St. Lawrence that it was difficult to build a road which would be wholly in British territory. So the British had tried in every way to avoid settling the matter. It was now arranged that the United States should have a little piece of Canada north of Vermont and New York and should give up the extreme northeastern corner of Maine. It was also agreed that criminals escaping from one country to the other should be returned. A still further agreement was made for checking the slave trade from the coast of western Africa. [Illustration: JOHN TYLER.] [Illustration: THE FIRST MORSE INSTRUMENT.] [Sidenote: The Morse code.] [Sidenote: First telegraph line, 1844.] [Sidenote: Usefulness of the telegraph, _McMaster_, 372.] 321. The Electric Telegraph.--Benjamin Franklin and Joseph Henry made great discoveries in electricity. But Samuel F. B. Morse was the first to use electricity in a practical way. Morse found out that if a man at one end of a line of wire pressed down a key, electricity could be made at the same moment to press down another key at the other end of the line of wire. Moreover, the key at the farther end of the line could be so arranged as to make an impression on a piece of paper that was slowly drawn under it by clockwork. Now if the man at one end of the line held his key down for only an instant, this impression would look like a dot. If he held it down longer, it would look like a short dash. Morse combined these dots and dashes into an alphabet. For instance, one dash meant the letter "t," and so on. For a time people only laughed at Morse. But at length Congress gave him enough money to build a line from Baltimore to Washington. It was opened in 1844, and proved to be a success from the beginning. Other lines were soon built, and the Morse system, greatly improved, is still in use. The telegraph made it possible to operate long lines of railroad, as all the trains could be managed from one office so that they would not run into one another. It also made it possible to communicate with people afar off and get an answer in an hour or so. For both these reasons the telegraph was very important and with the railroads did much to unite the people of the different portions of the country. [Illustration: THE FIRST MCCORMICK REAPER.] [Sidenote: Problems of what growing.] [Sidenote: The McCormick reaper, 1831. _McMaster_, 31-372.]