334 Scientific Intelligence. 



survey were to follow as nearly direct lines as practicable from 

 Honolulu to Midway Island, thence to Guam, thence to Luzon, 

 and also from Guam to Japan. Soundings were to be taken on 

 the outward voyage at intervals of ten and two miles alternately, 

 temperatures and nature of bottom being also observed. The 

 return voyage was planned to cross the primary route zigzag at 

 angles of 45°, the sides of the angle to be twenty miles in length: 

 soundings to be taken at the apices of the angles. In this manner 

 an examination was made of a belt of ocean about fourteen miles 

 wide and over 6,000 miles in length, unequalled in thoroughness, 

 so far at least as soundings are concerned, by any survey hithei'to 

 made of an ocean tract (p. 2). • 



Several submarine mountain ranges were encountered, the 

 most noteworthy occurring east of Guam, with peaks rising to a 

 maximum of 689 fathoms below the sea level, and valleys descend- 

 ing to a depth of more than 5000 fathoms. Four soundings 

 below the 5000 fathom line were made in the abyss now known 

 as the "Nero Deep." The deepest, 5269 fathoms, was about 

 seventy-five miles east-southeast from the island of Guam and is 

 the deepest sounding ever recorded, being only sixty-six feet less 

 than six statute miles. 



In computing the gradients from station to station serially on 

 the outward voyage only, involving 1,100 soundings, sixty-nine 

 localities only are found where the gradient exceeds 10 per cent. 

 Of these fifty have an incline between 10 and 20 per cent, eleven 

 between 20 and 30 per cent and six between 30 and 40 per cent. 

 The steepest declivity was found on the slopes of the peak south- 

 west of Midway Island, which rises to 82 fathoms beneath the 

 surface of the water. Here there is a change in depth of 1,269 

 fathoms (7,614 feet) in a horizontal distance of 1*8 sea miles, a 

 gradient of 70 per cent. With the few and localized exceptions, 

 the bed of the Pacific Ocean, as developed by this survey, though 

 rising here and there near to the sea level, and again descending 

 to depths of five to six statute miles, follows easy gradients. 



In commenting upon these results attention should first be 

 called to their great value. The first reconnaissance of the ocean 

 basins has already been completed and the results are embodied 

 in the various charts showing the bathymetric contours. What 

 is now most largely needed are detailed cross-sections such as 

 this supplies of the Pacific Ocean and which the necessity of 

 cable laying has fortunately secured. This has given some pre- 

 cision to the knowledge of submarine srradients along^ this line. 

 That such is lacking in the Challenger and Albatross cross-sec- 

 tions may be seen by noting the distance apart of the stations 

 except in the vicinity of land, and the resulting fact that the 

 gradients given by connecting the stations are in nearly all cases 

 comparatively flat lines, while the islands rise up with gradients 

 in striking contrasts. For this to be true would imply that there 

 were few or no submarine peaks of the same nature as those 

 forming the oceanic islands but falling short of the surface, an 

 assumption to be justly regarded as unwarranted and disproved 

 along the line of the present cross-sections. 



