BULLETIN 5'), UNITED STATES NATIONAL MUSEUM. 



From the above table it appears that the distance sailed while on 

 actual survey work was 21,519 g-eographical miles and the number of 

 soundings 2,074, or an average of one sounding at every ten miles of 

 distance run. Measuring the direct course of the survey, 6,144 knots, 

 there are records of soundings averaging one every three miles of the 

 route. 



PLAN OF SURVEY. 



The instructions regarding the survey were, in brief, 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 10 

 and 2 miles alternatel}^ ; temperatures of the air, surface and bottom of 

 the sea to be recorded; currents noted; samples of bottom material 

 brought up in a sounding cup to be preserved, etc. The return 

 course was planned to cross the primary route zigzag at angles of 

 45^, the sides of the angle to be 20 miles in length; soundings to be 

 taken at the apices of the angles. This plan was eflPectively carried 

 out, modified somewhat in detail by circumstances, 'especially as 

 regards intervals between soundings and detours from the main line 

 in order to develop marked irregularities of the contour of the ocean 

 bed. In this manner an examination was made of a belt of ocean 

 about 14 miles wide and over 6,000 miles in length, unequaled in 

 thoroughness, so far at least as soundings are concerned, by any sur- 

 vey hitherto made of an ocean tract. 



