The Sea Around Us by Rachel Carson Page B

recesses of the sea has been realized during the past decade. Persistent effort, imaginative vision, and engineering skill have produced a type of underwater craft capable of withstanding the enormous stresses imposed by the greatest depths of the sea and of carrying human observers into these realms that only a few years ago would have seemed beyond the reach of man.
    The pioneer in this area of deep ocean exploration was Professor Auguste Piccard, the Swiss physicist who had already attained fame through his ascent into the stratosphere in a balloon. Professor Piccard proposed a depth-exploring vehicle which, instead of being suspended at the end of a cable like the bathysphere, would move freely, independent of control from the surface. Three such bathyscaphes (depth boats) have now been constructed. Observers ride in a pressure-resisting ball suspended from a metal envelope containing high-octane gasoline, an extremely light, almost incompressible fluid. Silos loaded with iron pellets provide ballast; the pellets are held by electomagnets, to be released by the touch of a button when the divers are ready to return to the surface. The first bathyscaphe, provided by the Fonds National de la Recherche Scientifique, which is the Belgian scientific research fund, was known as the FNRS-2. (The FNRS-1 was the stratosphere balloon, which the Fund also provided for Piccard.) The FNRS-2, in experimental unmanned dives, revealed great promise but also had certain defects which were remedied in the craft built later. The second bathyscaphe, the FNRS-3, was built under a treaty between the Belgian and French governments, under the direction of Piccard and Jacques Cousteau. Before the completion of this bathyscaphe, Professor Piccard went to Italy to begin the building of a third bathyscaphe, to be christened Trieste.
    The FRNS-3 and the Trieste made the history-making descents of the 1950’s that carried man to the deepest parts of the abyss. In September 1953, Professor Piccard and his son Jacques descended in the Trieste to a depth of 10,395 feet in the Mediterranean. This was more than double the previous record. Then in 1954 two Frenchmen in the FNRS-3, Georges Houot and Pierre-Henri Willm, penetrated even deeper into the sea, to depths of 13,287 feet in the open ocean off Dakar on the coast of Africa. In 1958 the Trieste was purchased from the Piccards by the United States Office of Naval Research. The following year the Trieste was taken to Guam, in the vicinity of which lies the great Mariana Trench, in which echo soundings have revealed the deepest hole now known in any part of the ocean. On January 23, 1960, manned by Jacques Piccard and Don Walsh, the Trieste descended to the bottom of this trench, 35,800 feet (or nearly seven miles) beneath the surface.
    * From The Depths of the Ocean, by Sir John Murray and Johan Hjort, 1912 edition, Macmillan & Co., p. 649.
    * Even today the mystery of the scattering layer has not been completely revolved. Through an ingenious combination of new techniques, however, the picture is gradually becoming clearer. It now appears that at least in some areas—as over the continental shelf off New England—fishes may compose a substantial part of the layer. This has been determined by studying it with a sound source that embraces many frequencies (the ordinary echo sounder is a single-frequency device). This method not only reveals the vertical migration but brings out the fact that the very nature of the scattering changes with depth. Such changes are best interpreted as originating in the swim bladders of fishes, which are compressed under the increasing pressure of a descent into deeper levels of the sea but which expand with ascent toward the surface and consequent lessening of pressure. The formerly held objection that fishes could not possibly be abundant enough to account for the very widespread occurrence of the scattering layer has melted away in the light of information new