National Geographic : 1901 Jan
THE NATIONAL GEOGRAPHIC MAGAZINE THE PRINCIPLES UNDER LYING THE SURVEY OF THE BOTTOM OF THE OCEAN FOR AN ALL AMERICAN TRANS PACIFIC CABLE TO THE PHILIPPINES AND THE ORIENT. T HE object of such a survey is so to develop the mountain systems of the bottom of the ocean that every large change of elevation will be dis closed and allowed for in the laying of the cable; and the problem therefore is to determine the intervals at which deep sea soundings should be taken in order that important mountain systems may not escape detection and subsequent de velopment. The survey consists of two main parts: first, direct lines of soundings spaced at alternate intervals of ten and two miles passing between the successive landing stations at Honolulu, Midway, Guam, and Luzon, and also between Guam and Yokohama in Japan; and secondly, of sounding stations, twenty miles apart, at the turning points of a zigzag route pass ing back and forth to equal distances on each side of the direct lines of soundings. The direct lines were run in passing to the westward from California to tne Orient, and they give the general con tour of the bottom. The zigzag lines were run in returning to the eastward for the purpose of giving breadth and configuration to the forms indicated as a result of the depths measured along the direct lines. This distribution of sound ings was adopted as a result of a theo retical investigation giving the equation to the curve which, by revolution around a vertical axis, would generate the sur- face of an isolated submarine peak in which the crushing strength at any cross section is equal to the combined weight of the formation above that section and of the superincumbent body of water. Taking the origin of co-ordinates at the apex of the peak, and the axes of y and x to be vertical and horizontal re spectively, the equation to the generat K 28' ing curve would be y = + log x, in which K represents the coefficient of crushing strength of the materials com posing the crust of the earth, 8 the aver age density of these materials, and 8' the density of sea-water. The shape of the formation thus described resembles the form of the Eiffel Tower, but is much flat ter in proportion to its height. From the investigation of its proper ties it appears that the radius which a prominent orographic feature can have at the sea-bottom may be stated to be ten miles. An interval of ten miles coupled with an interval of two miles is the very longest that would be sufficient for gen eral development, but these intervals are small enough to prove with certainty the existence or absence of any formation rising close to the surface of the deep sea. Of all the possible ways in which a ten-mile interval could lie with reference to a submerged peak, that which would be most advantageous for a prompt dis covery is the condition in which one end of the interval is at the bottom of the slope and the other near the apex, and that which would be least advantageous is the condition in which the interval is bisected by the position of the apex. In the latter case there would be nearly equal soundings at both ends, but the soundings at the ends of the adjacent two-mile intervals would immediately disclose the slopes. E. W. LITTLEHALES.