Fast Search

You are Here: Home / Fulwell, Acoustical mirror

Tyne and Wear HER(4992): Fulwell, Acoustical mirror - Details

Back to Search Results


4992


Sunderland


Fulwell, Acoustical mirror


Fulwell


NZ35NE


Defence


Military Observation Site


Sound Mirror


Modern


C20


Structure


The Fulwell mirror has been revealed recently in modern reclamation work, and was designed to keep at bay German zeppelins. Examples of acoustic mirrors have long been known at RAF Biggin Hill and on the Kentish Coast, as well as in Malta. The mirrors are of three types. The Fulwell dish mirror was one of the Coastal Watcher type or Track Plotting Mirrors. It would have supplemented information derived from other sources such as the Radio Direction finding Stations, for example the Stockton on Tees Y station. This had a limited range of some 15 to 20 miles and was capable of giving a 4 minute Early Warning Alarm via London or the Senior Naval officers at Newcastle or Hull. The technology of these mirrors was remarkably modern. A signal was reflected by the dish to a collector head and thence to a receiver. The modus operandi was for the Duty Observer or 'Listener' to take up position in a bunker, usually in front of the 15 foot mirror with the stethoscope head-set connecting him to the collector head, usually an amplified microphone, above his own head. The optimum sound effect received, coupled with the Doppler effect, nicely illustrated the track of the intruder. By evolving an excellent reporting system, its course could be tracked and plotted sufficiently accurately to allow the anti-aircraft defences to take defensive action. The Fulwell mirror was of a similar type to the two Yorkshire examples at Redcar and Boulby. The Fulwell example consisted of an elevenft high rear wall, some 18 foot across, containing a 15 footmirror. This was made possible because the mirror was tilted backwards so that its axis was above the horizontal. This provides some evidence that its original purpose was to detect aircraft and not ships. It had two short walls for stability and to exclude ground noises. The noise of an approaching zeppelin's engine could be picked up some 15 minutes away. The Fulwell example has its own interest in that not only does the whole mirror seem somewhat smaller than the Redcar example, but the collector head may have been secured in front of the mirror by wires across the arms, so allowing the head to be variably positioned, unlike the fixed stand-pipe still surviving at Kilnsea. SCHEDULED ANCIENT MONUMENT AND LISTED GRADE 2


388


596


NZ388596



<< HER 4992 >> E.W. Sockett, 1990, A Concrete Acoustical Mirror at Fulwell, Sunderland, Durham Archaeological Journal, 6, 1990, 75-76 C.S. Dobinson, 2000, Twentieth Century Fortifications in England, Acoustics and radar, Appendices, Vol VII 2, p 156 Council For British Archaeology, 1995, Twentieth Century Defences in Britain - An Introductory Guide Handbook of The Defence of Britain Project, p 35-36; The Archaeological Practice Ltd., 2014, Fulwell Accoustic Mirror, Sunderland, Archaeological Assessment

Back to Search Results