The first known black woman inventor is Sarah E. Goode, who patented a folding cabinet bed on July 14, 1885. Since ethnic identity is not part of a patent application, it is impossible to be absolutely sure who was the first black female inventor. Another black woman might be the first, since Ellen F. Eglin of Washington, D.C., invented a clothes wringer before April 1890. While no patent was issued in her name, Eglin sold the idea to an agent for eighteen dollars, since she believed that it would be impossible for a black woman to exploit the device successfully. At the beginning of the twentieth century, Miriam E. Benjamin of Massachusetts, patented a gong signal system for summoning attendants on July 17, July 17, 1888; her invention was adopted by the U.S. House of Representatives to summon pages. By 1892, another black woman inventor emerged. In that year Sarah Boone received a patent for an ironing board. Her invention was a narrow board with a padded cover and collapsible legs, an improvement over the existing board that was placed across chairs for support.