It is around 1956. Diving begins to expand, and it is having success above all in the USA, where the Second World War did not cause upsets and huge poverty quite evident in Europe. The fortunate people who happily go diving with self-breathing apparatus mainly worry to remain without air; hose pressure gauges are rare. So, here is the genial idea of a device which, by lighting, signals the moment in which diver needs to begin his ascend.
It is proposed by the famous Desco company, presenting a small device to be inserted in the bracket between the regulator first stage and the bottle connector. When the pressure decreases behind the established limit, an electric contact closes and it lightens a bright warning light, a tiny lamp positioned at the end of a cable to be positioned in the mask side. Everything supplied by a small battery inserted in the device.
This system slightly reminds the Hud-Heads Up Display of which some of the most modern rebreathers are equipped.
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