. La composition de l'eau de mer : océanographie descriptive et comparative. L'eau de mer -- Composition. 498 [chap. 23 décennies a enregistré que la lumière du soleil pénétra apparemment sensible à cette profondeur. Mais cette expérience a été faite en vertu de l'observation directe d'un bathyscaph, il aurait été sans doute rendu compte qu'il était vicié par les éclairs et de zooplancton luminescents scintillations. On peut énumérer plusieurs catégories dans lesquelles aucune embarcation de recherche peut être particulièrement utile. Premier et le plus important, il permet l'inspection visuelle directe de l'eau mi-environnement et de la mer. Secondl

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. The Composition of sea-water : comparative and descriptive oceanography. Seawater -- Composition. 498 [chap. 23 decades recorded that appreciable sunlight apparently penetrated to that depth. But had this experiment been made under direct observation from a bathyscaph, it would have been realized that it was doubtless vitiated by the flashes and scintillations of luminescent zooplankton. One can list several categories in which any deep-research craft may be especially useful. First and most important, it allows direct visual inspection of the mid-water environment and the sea floor. Secondly, such a craft poten- tially enables selective sampling under visual control instead of remotely, blindly and randomly. The oceanographer's concept of the general environ- ment in which he is sampling and of how his sampler is operating may be far from reality. A third use is as a deep, quiet and stable platform for the scientist and his instruments. The chief value here lies in experiments needing elaborate electronic devices which cannot be readily self-contained, so that long electric cables must be used for deep measurements. Lowering a 3-mile-long multi- conductor cable from a surface ship is such a formidable task that few such experiments have ever been conducted. Fourthly, many geophysical measure- ments such as magnetic surveys, sub-bottom acoustic penetration, etc. can best be conducted in close proximity to the sea bed. 2. Diving Chambers Historically, diving chambers have provided oceanographers with their first means for penetrating the depths; hence brief mention of them is made here. Although such observation chambers are commonly employed for salvage, etc., they have never enjoyed wide oceanographic use—or at least few scientific publications have resulted. The Barton-Beebe bathysphere (Fig. 1), the French Telephone battery box C02 absorbing system Door. Communication hose — Stuffing box — Switch box Observation ports Searchlight 0? tank Fig. 1. A cutaway

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