In the mid 1870s at least three men were working independently toward electrical transmission of the human voice: Elisha Gray, a telegraph superintendent for Western Electric in Chicago; Alexander Graham Bell, a speech teacher for the deaf in Boston; and Thomas Alva Edison, a freelance inventor in Menlo Park, New Jersey. Amos Dolbeare, a professor at Tufts University, was another early telephone innovator. Bell applied for a patent on his invention on 14 February 1876, the same day that Gray registered his work on such a device. Bell's patent, issued on 7 March, became one of the most profitable and contested patents of the nineteenth century. On 10 March the first spoken words traveled over a wire when Bell said to his assistant, "Mr. Watson, come here, I want you." Over the next several months professors at Brown University worked to make Bell's invention smaller and more practical...