The first foghorn (in the country? in the world? Unclear) was located at Boston Light. It was requested by the third keeper, John Hayes. It was a cannon that was fired during times of fog to warn ships. It was on display at the United States Coast Guard Academy in New London, Connecticut until 1993 when it was returned to its place at the base of the lighthouse tower on a new carriage
A photo of the cannon in its current location can be found at http://www.lighthouse.cc/boston/history.html.
1 Public Broadcasting Service (PBS). "Legendary Lighthouses: Great Lighthouse-North America" [Online] Available http://www.pbs.org/legendarylighthouses/html/natlgl.html, February 17, 2005.