Sound mirrors in the Financial Times

An article about sound mirrors by the security and defence editor of the Financial Times.

Forgotten, dilapidated and, in one case, buried by the local council as an eyesore; these smooth, spherical concrete structures known as acoustic mirrors provided the UK with its first early warning system against German air attack during the first world war.

Source: Joe Pettet-Smith’s photographs of the UK’s early warning air defence system, David Bond, Financial Times, 20 July 2018.

It even quotes this website!

Forgotten technologies: Giant ears of concrete

Vergessene Technologien – Riesenohren aus Beton” (Forgotten technologies – Giant ears of concrete) is a 23 May 2011 German-language article by Solveig Grothe on the website of Spiegel. It has a history of sound mirror development between the wars, and features some photos of sound mirrors from the Sound Mirrors Flickr group (used with the permission of the photographers).

With reinforced concrete shells the size of a house, the British listened in the 20s and 30s for enemy aircraft. The acoustic experiments along the coast gave the island extraordinary architectural monuments – and an interception technique to which was used to the outbreak of World War II.

Und jetzt, die artikel auf Englisch: Listening for the Enemy, Giant Ears on the British Coast

The Tizard Mission

… visual detection was often hampered by the island nation’s overcast skies, and the technological means of spotting aircraft were primitive at best. One scheme involved a massive concrete “sound mirror” that picked up the noise of an approaching engine—unfortunately, though, the device wouldn’t have been able to distinguish between the invading Luftwaffe and a passing British lorry. A technological breakthrough was needed….

Source: Review of “The Tizard Mission” by Stephen Phelps at the Wall Street Journal, 2011-03-12

Amusingly, alongside the review is a link to an article Opinion: Japan Does Not Face Another Chernobyl by a William Tucker. Obviously this isn’t the William S Tucker who was involved in the development of sound ranging!

Conservation techniques and the Denge sound mirrors

… One of the largest projects funded by the Aggregate Levy Sustainability Fund and managed by English Heritage was concerned with stabilizing these structures and undertaking research into their repair.

This paper aims to outline the conservation approach to the project and to detail the concrete repair techniques trialled. It also highlights some pointers for the repair of twentieth-century concrete based on the advice of a master mason and a concrete repair contractor. Finally, the long-term monitoring that is in place for the carbonation inhibitors and cathodic protection systems that are installed on these structures are detailed.

The Listening Mirrors – A Conservation Approach to Concrete Repair Techniques by Alan Wright and Peter Kendall. Journal of Architectural Conservation, Volume 14, Issue 1, March 2008

The Geek Atlas

The Geek Atlas is a new book by John Graham-Cumming published by O’Reilly, the people who do those techie books with animals on the covers (and as a result made me want to slash and burn any East Indies jungles where tarsiers might live).

The reason for mentioning the book here is that one of the sites listed is Denge, for the three sound mirrors.

The Geek Atlas book cover

The history of science is all around us, if you know where to look. With this unique traveler’s guide, you’ll learn about 128 destinations around the world where discoveries in science, mathematics, or technology occurred or is happening now. Travel to Munich to see the world’s largest science museum, watch Foucault’s pendulum swinging in Paris, ponder a descendant of Newton’s apple tree at Trinity College, Cambridge, and more.

Each site in The Geek Atlas focuses on discoveries or inventions, and includes information about the people and the science behind them. Full of interesting photos and illustrations, the book is organized geographically by country (by state within the U.S.), complete with latitudes and longitudes for GPS devices.

Destinations include:

Bletchley Park in the UK, where the Enigma code was broken
The Alan Turing Memorial in Manchester, England
The Horn Antenna in New Jersey, where the Big Bang theory was confirmed
The National Cryptologic Museum in Fort Meade, Maryland
The Trinity Test Site in New Mexico, where the first atomic bomb was exploded
The Joint Genome Institute in Walnut Creek, California

You won’t find tedious, third-rate museums, or a tacky plaque stuck to a wall stating that “Professor X slept here.” Every site in this book has real scientific, mathematical, or technological interest — places guaranteed to make every geek’s heart pound a little faster. Plan a trip with The Geek Atlas and make your own discoveries along the way.

The Geek Atlas. ISBN: 9780596523206, 542 pages, £22.99

Denge sound mirrors feature in prize-winning graphic story

Julian Hanshaw won the 2008 Observer/Cape Graphic Short Story Prize with Sand Dunes and Sonic Booms, described by the Observer as a “haunting, evocative and beautifully drawn story”. It is set on the south coast, and at the Denge mirrors in particular.

We loved Hanshaw’s sense of time and place – an effect he achieved partly through a series of sepia frames illustrating the south coast. Hanshaw is an animator by training, and moved to Winchelsea, East Sussex from London three years ago. Since then he has become ‘mildly obsessed’ with the area, particularly the spectral and strange Dungeness. The idea for ‘Sand Dunes and Sonic Booms’ came after a visit to one of the south coast’s sound mirrors – primitive devices designed to detect and track military aircraft before the First World War (though the ones in Kent date from the 1930s).
Source: The Observer 2009-11-09

You can read the story here: Sand Dunes & Sonic Booms.

Air War Over East Yorkshire book

Over Christmas I read Air War Over East Yorkshire, an interesting book by Paul Bright about WWII aviation in the East Riding.

It avoids the dryness of a lot of military books, and unusually has a fair amount of data about the Luftwaffe as well as the Allied forces. It discusses the radar stations in the area, including RAF Staxton Wold, possibly the oldest active radar site and with a history as an early warning site stretching back pretty much forever.

Air War Over East Yorkshire

In most accounts of the air war over Britain in summer 1940, the events over East Yorkshire are mentioned only in passing, yet it was there, on 20 August, that the first enemy aircraft fell to the guns of a Polish fighter squadron in the RAF, less than a mile from where these words are being written. It was also where the ‘north-east town’, as Hull was identified in the news bulletins of the day, suffered its prolonged agony under the bombs of the Luftwaffe. Indeed, the very last British civilians to die as a direct result of Luftwaffe bombs in World War II were killed in Hull on 17 March 1945. As the home of much of the RAF’s night-bombing force, East Yorkshire was also frequently the scene of Luftwaffe night intruder raids. This book, based on years of in-depth research into primary sources, personal accounts and experiences, reveals many new facts and gives long-overdue recognition to the events and people who fought, lived and all too often, died, in East Yorkshire during 1939-1945.

Paul Bright, now a retired history teacher, was born in Hunmanby, then a part of East Yorkshire, and as a schoolboy witnessed at firsthand quite a few of the events described in this book. His father was an auxiliary fireman in Hunmanby who participated in the response to many of the air attacks and their aftermath. Other members of his family endured the Blitz in Hull, consequently he is able to write about the period from personal experience as well as from the perspective of the dispassionate historian. He lives in Filey.
Source: Flight Recorder Publications

Pillboxes of Britain and Ireland book

Cover of Pillboxes in Britain & Ireland I’ve acquired a copy of the newly-published book Pillboxes of Britain & Ireland, by Mike Osbourne.

While it doesn’t cover sound mirrors, it is an excellent and comprehensive book on pillbox design and development, with typologies, plans, photographs and details of the theory and use of pillboxen. It is well worth any connoisseur of concrete defensive structures getting hold of a copy.

While we’re at it, I’ll also mention another good recent read, the new Osprey book on Armored Trains. I would review it, but this review says it all pretty well.

Unfortunately the book doesn’t mention the armoured train in Sarajevo.