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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. 



THE 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 

 M^ere 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- 



ing curve would be 3; = r- + 



o 



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- 



28' 

 ^ logjr, 



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 couplea 

 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. AV. LITTLEHALES. 



