Cometh The Hour…
Last month marked the centenary of the first ever ‘air raid’ on the UK. In January 1915, two Zeppelin navel airships flew over the east coast of England and bombed great Yarmouth and King’s Lynn. With the first attack on London being on the 1st of May. This of course represents a significant landmark in the development of warfare. The true significance of which would be revealed some 2 decades later. And which needs little further comment.
But this week I stumbled upon a little known episode from those earliest days of air warfare. As the scale and scope of the Zeppelin threat began to dawn. The minds of those tasked with the defence of British skies began to turn to the challenge of detection and destruction of approaching raiders. And ideas for a new secret weapon began to form.
At a conference attended by delegates from the Blind Institute, in early 1915, the then Chairman of St Dunstans Sir Arthur Person, made a top secret announcement. That‟ the National Air Board required 1,000 “intelligent blind men” to provide early warning of the approach of aircraft. Their sense of hearing being “developed to a greater degree of „sensitivity”
In his book; Dear Old Blighty, Ernest Sackville Turner describes how Commander Alfred Rawlinson, in charge of anti aircraft defence, employed blind men in 1915 to sit on the top of high buildings. Listening for the distant throb of Zeppelin engines. In south-east England they manned a binaural listening service which fed information of range and altitude to the defences.
This early form of acoustic location was based on our instinct to turn our heads towards the source of a sound., so we can hear it equally in both ears. The system involved the visually impaired volunteers being equipped with a stethoscope to enhance their hearing. In order to determine the direction of the raider, a pole was attached to the volunteer’s head,. Which, when turning, would indicate the bearing on a compass dial.
From these fledgeling efforts at acoustic location, sound detection technology evolved. The development of more sophisticated, sensitive and accurate mobile horn receivers and fixed acoustic mirrors, often constructed from concrete, or in one notable example, a Kent cliff face, enabled acoustic location to be operated by sighted operators. Even with their less sensitive hearing! Acoustic location formed the primary method of advanced warning of air attack on the UK, until the beginning of WW2. When it was rendered obsolete by the introduction of RADAR. But for 20 years British air defence was dependent on a system that owed it’s origination to a handful of brave Blind men perching on the rooftops of London. During the 1915 Zeppelin raids. Happy 100th anniversary guys! Wherever you are!