By the time the scientists approached the pier, the boys had explored the central part of the island and had returned to the cottage lugging planks found in the ruin of a cottage apparently blown down by some long-past hurricane. They dropped the planks beside the house and hurried to catch the line that Zircon threw, then they warped the Water Witch in to the dock.
All hands turned to, and in a short time supplies were unloaded and stored, beds were made with linen and blankets loaned by Dr. Ernst, and the cottage began to take on an inhabited look.
While Tony Briotti began preparations for dinner, the boys carried their aqualung equipment to the shed at the rear of the cottage and began to check it over. Since their lives would depend on proper functioning of the equipment, they inspected the regulators carefully, checking the condition of the neoprene flaps. Once checked, the regulators were hung on nails on the shed walls, out of harm's way.
The next step was to inspect the tanks. Rick had already looked them over, but for the sake of safety the boys did it again. There were six of them, each of seventy-cubic-feet capacity. There was an advantage to this particular capacity at the depth where they expected to dive; a diver could work only fifteen minutes at 120 feet without requiring decompression, and seventy cubic feet of air would last just long enough. Double tanks would have meant the boys would be able to stay down nearly twice as long, but would also have meant the nuisance of waiting through the decompression period of about thirteen minutes ten feet below the surface on the ascent. For this reason, the boys planned to dive with single tanks, leaving the spares on the surface.
Of course, to get even fifteen minutes of diving at twenty fathoms the tanks had to be filled to capacity. When full, they were under enormous internal pressure of over two thousand pounds per square inch. The tanks had been filled at Spindrift, but the boys decided to check them again, in case there had been some leakage through the valves during shipment.
Scotty swung one tank upright and prepared to attach the pressure gauge. Rick, inspecting another tank for bumps that might have weakened the tank wall, saw him do it.
For a moment Rick continued his inspection, then what he had seen suddenly registered. He yelled, "Scotty! The valve!"
In that instant, as Scotty attached the pressure gauge, the valve blew out!
The entire valve assembly and the pressure gauge, propelled by the tremendous pressure in the tank, blew straight upward, ripping clear of Scotty's hand and taking a patch of skin along. The ascending assembly, traveling with bullet speed, clipped a lock of hair from his bent head.