applications of this method have been made in France by Commander de Roujoux and by Captain Trudelle for landfalls in different localities, along the Channel, at the entrance to New York, Havre, Brest, and the very dangerous approaches to Cape Guardafui. Two oceauographic coordinates have taken the place of the astronomical coordinates. The vessel, having lost her sight, makes use of feeling. To draw up bathymetrical and lithological charts is one of the principal objects of oceanography.
Oceanography has to maritime fisheries a relation still more important, if that is possible, than to geology, meteorology, and navigation, for this industry is related closely to the very life of nations. In France we have more than 86,000 marine fishermen, while more than 200,000 people derive, directly or indirectly, their means of existence from fishing; as, for instance, the men and women employed in the canning factories.
There are very many marine animals of which man makes use either as food, such as fishes, crustaceans, certain mollusks such as oysters and mussels, or to gratify his needs of all sorts, as sponges, pearls, coral, the great cetaceans, as whales or cachalots, and seals, from which he obtains oil and skin. No being escapes from the influence of the surroundings in the midst of which he lives and which govern his material existence as well as his manners, his morals, and his intellectual faculties. Nowhere are these restrictions more strikingly evident than in the water, probably because they are found there in a state of the greatest simplification or, to be more exact, the least complication. The laws of oceanography are, then, the rational basis for the conduct of fisheries, which have become methodical and consequently scientific, and pisciculture is a kind of agriculture of the sea.
In the harmony between a being and his environment, three cases present themselves: If the harmony is perfect, the being, finding the utmost satisfaction for his needs, develops and multiplies; if it is only partial, the being who suffers it becomes rare; if, finally, the harmony is absent, the being will disappear by flight if he possesses, like an animal, the power of motion, or by death if, like a plant, he is condemned to remain in one place. The living creature thus indicates in three ways the condition of his surroundings—by his presence, his rarity, or his absence. Dredgings made even in great depths show in a striking way the extreme specialization in the distribution of the animal species, among which some are evidently more sensitive to the environment, others less so. Each special group conforms to corresponding, special, exterior conditions, physical, chemical, or mechanical, and in this way the animal, vegetable, and, to a certain degree, even the mineral becomes an instrument of measurement, roughly graduated, it is true, because while abundance or absence are relatively easy to recognize, nothing is more vague and less determinable than degrees of rarity. A fish found in a certain locality indicates that the water there possesses a depth, a temperature, a certain limited range of salinity, a
