The Diaphone was invented by English Organist Robert Hope Jones of the Hope Jones and later Wurlitzer organ companies. The Diaphone was Patented in 1910, by Professor John Pell Northey of Toronto University, after buying the rights to the design from Robert Hope Jones. The diaphone was Jones’ answer to a search for a rich bass voice in the organ. The Diaphones designed by Professor John Pell Northey were originally used as fog horns for use on the Great Lakes and along the coast. In the years to come, these horns were later produced by the Gamewell Company (famous for fire alarm/call boxes) and adapted as warning horns. Although Northey’s fog horns were either single tone or dual tone, it should be noted that Gamewell’s Diaphones were strictly single tone. These horns were and still are, used at fire stations all over the country to alert the public and firemen that there was an emergency. Coded “honks” or blasts are sent out. The number of honks tell the firemen what they have, and quite often where the incident is located. They are also used by local governments for use in alerting the community that a curfew is in effect. They are popular in the New England States, particularly Mass., as the Gamewell Company was located in Newton Mass.
For the complete account of the invention and use of the diaphone as a concept for the pipe organ and later as a fog horn, please refer to this website: http://www.terrypepper.com/lights/closeups/fogsignal/diaphone/diaphone.htm