Today in history: On May 10, 1869, a golden spike was driven in a ceremony in Promontory, Utah, marking the completion of the first transcontinental railroad in the United States. Also on this date: In 1775, Ethan Allen and his Green Mountain Boys, along with Col. Benedict Arnold, captured the British-held fortress at Ticonderoga, New York. In 1865, Confederate President Jefferson Davis was captured by Union forces near Irwinville, Georgia. In 1924, J. Edgar Hoover was named acting director of