TOWT and I have just returned from our annual pilgrimage to Mauritius. For the younger end of the tourist market there it is a mecca for watersports and particularly scuba diving. For some unaccountable people seem to want to get close to the fish and coral that surround the island. For us viewing from a glass-bottomed boat is close enough, thank you very much.
Watching the antics of the scuba divers my thoughts soon turned to musing about who it was who pioneered the development of the support system needed to promote scuba diving and this is where our latest, somewhat shadowy, inductee to our Hall of Fame, Sieur Freminet comes in.
For those of you who are aficionados of the art of scuba diving there are two basic configurations. One is called the open-circuit where the diver passes the exhaled air into the environment and requires the diver to take their breaths of air from a diving regulator. The other form is known as the rebreather where the equipment the diver uses recycles the exhaled gas, removes the carbon dioxide and compensates for the used oxygen before the diver is resupplied with gas from the breathing circuit. The amount of gas lost per circuit depends upon the design of the rebreather and the depth change during the breathing circuit.
I suppose those who wish to spend a prolonged amount of time underwater are trying to rediscovery man’s piscine origin and the problem of how to breathe effectively underwater has taxed many a mind, some great, some less so, over the centuries. By 1771 a British engineer, John Smeaton, had invented an air pump which when connected to a diving barrel by means of a hose allowed air to be pumped to a diver.
But 1772 saw a major breakthrough thanks to the endeavours of our French hero. Freminet developed what he called his machine hydrostatergatique which was a form of breathing machine which would be classified as a rebreather today. The diver was equipped with a helmet, two tubes – one for inhalation and the other for exhalation – a suit and a reservoir which was dragged by and behind the diver. In a later adaptation Freminet strapped the reservoir to his back.
Although precise details are somewhat sketchy, it seems that our hero used his device successfully in the harbours of Le Havre and Brest for at least 10 years judging by the inscription to a painting dating to 1784 Freminet sent six copies of the treatise he wrote publicising his machine and spoke on the subject on 5th April 1784, as the records of the Chamber of Commerce of Guienne records, noting the purpose of the invention as being in case of shipwreck or to investigate blockages in water channels.
There was, however, one inherent design flaw in the equipment. The system of inhalation and exhalation into the one tank meant that in the event of prolonged use the levels of oxygen were depleted to dangerous levels. Alas, for our hero but the stroke of fortune that guarantees his place in our hallowed Hall of Fame, he died from lack of oxygen after being in his own device for twenty minutes.
A worthy inductee, indeed.
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