As the Swarkestone bound leg of Route 6 passes through Alvaston Park, we now come across what appear to be a pair of concrete satellite dishes about 2m high, facing each other and about 50m apart.
|This is what they look like.|
Well, if you have ever walked the paths on top of the White Cliffs of Dover, you will have seen something similar but larger, and therein lies the answer. Those were built in the years prior to the start of WW2, before the invention of radar, as a means of magnifying the sound of enemy aircraft approaching across the Channel. A microphone was positioned at the focus of the curvature being connected to a pair of headphones in a nearby shed. Not surprisingly, the invention of radar made these things redundant.
Those on the White Cliffs between Dover and Folkestone, are about 15 feet high.
We are not so slow here in Derby in catching up with the 1930's technology, so here we have a pair of our very own concrete ears which you can try out for free providing that you have a companion. who can whisper sweet nothings into one concrete ear whilst you listen, no less that 50m away, to this enhanced sound at the other ear.
If you are on your own and fancy yourself as a 50m sprinter, you could try speaking into the one ear and running to the other ...................................