4 BULLETIN 55, UNITED STATES NATIONAL MUSEUM. 



appears at station 124, followed by depressions to more than 2,600 

 fathoms a few miles away, both to the westward and northward. 

 With these exceptions the range of variation is practically between 

 2,500 and 3,000 fathoms for the whole distance until the immediate 

 vicinity of the Midway Islands is reached. 



About 30 miles to the southward and westward of Midwa}- Island a 

 very bold peak was discovered rising- abruptly from the ocean floor, 

 2,000 fathoms below the sea level, to a height only 82 fathoms below 

 the surface. 



Passing from the vicinity of Midway Islands a nearh^ level plain is 

 found, extending about 1,000 miles to the westward, upon which the 

 extremes of depth of water are 2,926 and 3,382 fathoms. About mid- 

 distance between Guam and Midway Islands what is apparentlj^ a 

 mountain range is encountered, extending over 3^ of longitude, with 

 varying depths from 3,000 to 720 fathoms. On the westward side of 

 this mountain range another plain below the 3,000-fathom line extends 

 a distance of about 300 miles. From the western limit of this plain 

 until Guam is reached the contour is quite irregular. Extensive detours 

 both north and south of the direct course developed a mountainous 

 region, with peaks rising to 689 fathoms below the sea level, and val- 

 leys descending to a depth of more than 5,000 fathoms. Four sound- 

 ings below the 5,000-fathom line were made, with the record of 5,070, 

 5,101, 5,160, and 5,269 fathoms. These were in the ab3^ss now knowm 

 as the "Nero Deep."" The last-named sounding was numbered 1488, 

 in latitude 12^^ 43' 15" north, longitude 145"^ 49' east, about 75 miles 

 east-southeast from the island of Guam, and is the deepest sounding 

 ever recorded, being onlj^ 66 feet less than 6 statute miles. 



From Guam to Luzon the ocean bed is for the most part gently 

 undulating, at depths varying from 2,500 to 3,000 fathoms. About 

 120 miles west of Gaum (station 688) there appears a sharp elevation to 

 1,346 fathoms, which however soon subsides to the normal depth of 

 about 2,700 fathoms. Again, about 600 miles from Guam (station 

 760) a rise to 1,560 fathoms is encountered. From the data at hand 

 this latter would seem to be a peak rather than a mountain range, 

 since soundings east, west, and south show speedy subsidence to nearly 

 normal depths. At station 784 the depth reaches 3,547 fathoms, with 

 several soundings in that vicinity below 3,000. Approaching Dingala 

 Bay on the east coast of Luzon and about 120 miles distant (station 

 864) another peak appears with summit only 821 fathoms below sea 

 level. In this instance also, soundings north, east, and west soon 

 develop normal depths. 



From Guam to Yokohama the route lies to the westward of the 

 Ladrone Islands and to the eastward of the Bonin group. For a dis- 

 tance of 500 miles or more from Guam the soundings show a gently 

 undulating plain at an average depth of about 2,100 fathoms. Between 



