The two men who were to operate the bell climbed over the rail and stood on the outer edge as the bell was brought alongside. As you recall, the fantail of the FALCON is very low in the water so as to make it easy to handle divers and diving operations. When the bell came alongside they stepped on its top and climbed down through the hatch and into the brightly lighted operating compartment. Everyone watched as they dogged the upper hatch securely and in our mind's eyes we were with them as they sat down amid the pipes, valves, and control gauges that were an integral part of the operating compartment. I could see them bending over and looking down through the eye port of the lower hatch which led to the central lower compartment of the bell and in which the reel that wound the downhaul wire was located. This compartment was simply a cylindrical extension open to the sea at the bottom. It could be flooded by allowing air to escape, and water could be blown out by building up the air pressure to be slightly greater than that of the surrounding sea. Around this lower compartment was a ballast tank which could be either filled with water or blown empty.
McCann ordered "blow ballast" and I could imagine the boys as they opened the line which allowed air pressure from the FALCON'S compressors to blow water out to sea from this circular tank around the lower compartment. Soon we could see air bubbles coming up from the bell and we knew the tank was empty. Simultaneously with appearance of the bubbles we heard the telephone report from the bell, "Ballast has been blown," I knew the next move would be for the operators to flood the lower compartment. This was easily done by simply allowing the air trapped in the compartment to escape and the sea automatically to fill the space. The reel attached to the downhaul wire had already been placed in position before the bell was lowered over the side; all that remained now was to start the air driven motor which turned the reel in the flooded lower compartment. Soon the wire began to take a strain and the report from the bell was, "On the way down.”
We soon lost sight of the bell but received reports from time to time: "We're at 100 feet; we're at l25 feet; we're at l50 feet." They were, of course, reading from the depth gauge inside the operating chamber. At 200 feet they peered through the lower port and reported they could see a large object on the bottom. They moved cautiously, a few feet at a time now, and before long the happy word came, “The hatch is in sight." They then allowed the motor to pull the bell tightly against the steel gasket surrounding the forward torpedo room hatch, thus fitting the rubber gasket on the bottom of the bell directly on the stell gasket. Great skill was required to manipulate the motor so as to pull the bell into position without breaking the wire.
The next two operations were practically routine for this well-trained pair. They flooded the circular ballast tank in order to gain weight and took in on the downhaul wire during the flooding period so that the bell was snugly held to the submarine. Then they blew the air out of the open ended central compartment. After making certain that all of the water was blown out of this lower compartment they vented the air to the surface, and thus they had atmospheric pressure in the lower compartment. In doing this they secured themselves with the entire pressure of the sea pressing against the bell and forcing it against the submarine. They knew that the rubber gasket of the bell was now flattened against the circular steel gasket on the deck of the submarine. They were taking advantage of the pressure of the ocean for once rather than battling against it as they had to in their diving suits.