Physicist Brian Ray, testing the carbon dioxide content of the atmosphere in Sealab II, Britain's first permanent underwater laboratory, 30 feet beneath the waves off Plymouth. A couple of years after the expedition to Paradise Bay (see Underwater House Malta), David Baume from Enfield College of Technology and his team of sub-aqua enthusiasts made another attempt to construct an underwater home, this time off a breakwater in the middle of Plymouth Sound. Instead of using rubberised fabric, the new structure featured a massive cylindrical steel tank. This was lowered into the harbour and weighed down with several tons of pig iron ingots. These were lowered beneath the tank by means of a fairly primitive pulley system and then had to be manhandled off the trolley and positioned under the ?house?. The water was almost pitch dark, extremely dirty and very cold. It took more than 200 dives to complete the operation and ensure that, when filled with air, the cylinder would stay on the bottom of the harbour rather than rise to the surface and turn turtle, with potentially fatal consequences for those inside. But finally the underwater house was ready for occupancy and fitted with the special air scrubber that David and his team had developed to ensure the air remained fresh. Several members of the team spent considerable periods of time living beneath the waves, turning the workbench into a bunk bed for overnight stays.