– John Coldwell (assistant Keeper to Walt Tansky on Pulteney Point 1969 – 1972)

The diaphone is a unique organ pipe. The theory was based on a design for the Wurlitzer pipe organ invented by Robert Hope-Jones dating from 1895.

A special tone generator in the organ involved a piston vibrating inside a cylinder, which had slots through which air was discharged. The air passing through the slots caused a vibration which when amplified through a long cone (like a megaphone) created a powerful harmonic sound.

Robert Hope-Jones also applied this principle successfully to foghorns, and this then became the most common type of navigational aid in the world. Continue reading ‘F’ Type Diaphone Foghorn c. 1969 →