Library of Congress CCN 67-10417
In this building is a room at a dead end, isolated, silent.
The doorway has a light lock to keep out daylight. There
is no way for light to come in from the outside. In the room is a large cube-shaped tank eight feet in each dimension. The room's air IS warm and wet (85_F) and 100 per cent relative humidity. With the lights tumed off the feeling is of a warm, wet, soft blanket gently enfolding one in the intense darkness.
The tank is fiiled with sea water to the top_9 tB2 tons of it. The water is kept at a constant temperature anywhere from 88_F to 95_F by a special fresh water thermostatic heater. The walls are insulated thermally from the outside walls and the floor. A six-foot man cam stand inside the tank on tiptoe and keep his nose and mouth in the air with the rest of the body immersed.
if one's body fat and muscles are correctly distributed, he can float horizontally on his back just far enough underwater to keep his nose in the air. Most of the rest of his body remains immersed. With his hands under his head to keep the strain off his neck, he can relax and even doze off. With the lights on for many hours and many different exposures, he undergoes training to be able to trust himself to be completely relaxed under these conditions.
One notes immediately that the water enters his ears and cuts off whatever small sounds were still left in air. He may begin to imagine himself in the situation of the dolphins. If there is a residual sound in the water, he hears it as immersion starts. The airbonne sounds have been reduced in intensity from nine hundred to several thousands of times. He immediately sees the difference between our hearing in air and that of a dolphin under the water. If someone speaks in the air above the tank the voice heard underwater is reduced to this same degree; he barely hears it. (The dolphin's hearing umderwater is very much better than ouns and hence they can hear these voices better than we can, Our ear is adapted to airborne kinds of sound waves; underwater the drum is loaded with water so it works less efficiently,) The freedom of movement, of slow movement, is positively sensuous. One can assume many different positions without much effort. Once one accommodates and develops the proper reflexes to keep his nose m air, the freedom of movement and the rewards thereof become appreciable.