Charles Benedict Calvert telegraph, Samuel Morse and Alfred Vail. On April 9, 1844, Morse and Vail successfully tested their device by transmitting a message from the nation's capital to the Calvert home, Riversdale. This test came 45 days before the more celebrated event when Morse sent the message "What hath God wrought?" from Washington to Baltimore, along telegraph lines that ran above the Baltimore and Ohio Railroad line near Riversdale. Calvert became president of the Prince George's County, Maryland Agricultural Society and the Maryland State Agricultural Society, and served as vice president of the United States Pomological Society. He founded the first agricultural
Signal Corps in the American Civil War instrument. The first model train was constructed by Henry J. Rogers, a telegraphic engineer from New York City who had worked with Samuel F.B. Morse in building the first commercial telegraph line between Washington and Baltimore in 1844. Rogers's original telegraph instrument for the train replaced the traditional sending key and sound receiver with a dial indicator, a circular index plate bearing the letters of the alphabet and a pointer that turned to the letter to be transmitted. A similar pointer spelled out the message at the receiving end. Rogers provided a galvanic battery that eliminated the danger of acid