Porpoise was diving equipment developed by Ted Eldred who’s show at the third picture here below, he’s sitting on the left. His first project was an O2 rebreather. It had a safety device making it stop at the depth of 10 meters ( oxygen becomes poisonous when aspired under a to high pressure ) The project did not come further then a prototype and was abandoned after Ted Eldred had built compressed air scuba equipment with demand valves.
