View Full Version : Archived: Kilnsea Sound Mirror

compound eye
08-02-2011, 08:47 PM
Sitting in a cornfield atop the fast eroding cliffs of Kilnsea is one of the earliest examples of the acoustic or sound mirror - a means of amplifying the engine sounds of approaching Zeppelin airships intent on bombing the docks of Hull.

Although it must have provided little in the way of early warning, in the days before electronic detection, it must've been a morale booster, and a confusing sight for the German airship pilots...

The sound bouncing back from the concrete dish was angled into a collector that used to be mounted atop the rusty pole at the focal point, in place of the [ahem] WW1 gaffer tape that's there now. It probably - based on pictures of other primitive detection systems - looked like a small gramophone horn connected to a long stethoscope, which the operator listened in to.

Recent tests of such arrays have suggested they might have provided a 20-40% increase in warning time over listening with the human ear alone. Not bad for two parts sand, one part cement, three parts gravel..!

Just one photo for this - the back is plain, and it's not like there is any intricate detail to see...