Since I've been going on about the Sound Mirrors on the Denge Marsh in Kent, I thought I'd better put them up for scrutiny. The most memorable is the 30 foot diameter mirror, still with its microphone stand. Microphone? Is this a Hollywood Bowl-style amphitheatre, waiting for Sinatra to come on and croon across the shingle flatlands? No, this is an acoustic bowl constructed in concrete in the late 1920s in a series of experiments to find a away of foretelling the arrival of aircraft approaching across the English Channel. Next to this mirror is a 20 foot version, like a child next to its mother, and a colossal 200 foot wall which only has one other like it, and that's in Malta. Microphones at the acoustical centres were attached by leads to headphoned boffins hiding in concrete bunkers underneath. They are such a superb example of 'Dead Tech', a brief reaching out into the unknown for the defence of the realm. A narrow gauge railway was built to bring the materials across the shingle, and one can easily imagine top brass arriving for a demonstration in an Avro Andover at Lydd Airport next door. To a degree they worked, except they also picked-up shipping passing by the Ness and were quickly superceded by radar in 1932. But somehow I get the feeling they're still listening to everything going on, and not just the mewing of birds on the gravel pits that now surround them..
Harry Willock: The man behind the curtain / Part one
11 hours ago