46 



Results of compensation 



Note. — Correction of +4° and correction of +2 fathoms. 



The apparatus was used to determine depths on numerous oc- 

 casions with very favorable results. Depths obtained in this manner 

 were checked by hand soundings, taken while the vessel was hove to, 

 and were found to be accurate to the nearest fathom up to the 

 limits of the sounding machine approximately 200 fathoms. Depths 

 ranging from 13 to 2,500 fathoms were determined by the use of 

 the time method. 



Experiments were carried out on different types of bergs, both 

 large and small, in shallow and deep water, and in soft and hard 

 bottom. Following shows the method of procedure in carrying out 

 these experiments: 



(o) Conditions. — Latitude 45° 48' N., longitude 46° 57' W. Depth of water 

 2,300 fathoms. Character of bottom, muddy. Temperature of sea, 38; 

 temperature of air, 39. Size of berg above water: Height, 200 feet; 

 length, 300 feet; shape, irregular. 

 Observations. — Steamed toward and around berg at various speeds and from 

 the berg at various distances, but no echoes were received. Stopped at 

 various distances, around the berg, but no echoes were received. 



(6) Conditions.— Latitude 44° 25' N., longitude 48° 10' W. Depth of water, 

 1,800 fathoms. Character of bottom, tine-grain sand and small gravel. 

 Temperature of sea, 39; temperature of air, 44. Size of berg above 

 water: Height, 100 feet; length 250 feet, shape, irregular. 

 Observations. — While stopped, with berg abeam, echoes could be heard at 

 1,000 yards. Steaming at 10 knots toward berg, no echoes could be 

 heard. Circling the berg at a range of 1,000 yards, weak echoes were 

 heard, varying considerably in intensity, the loudest echoes being re- 

 ceived when the bottom echoes were at a maximum. Circling the berg 

 at a range of 1,500 yards, weak echoes were occasionally heard. While 

 circling the berg better results were noted with the berg bearing abeam 

 or aliaft of the beam than with it bearing forward of the beam. 



(c) Conditions. — Latitude 47° 17' N., longitude 47° 55' W. Depth of water, 

 120 fathoms. Character of bottom, gravel. Temperature of sea, 38; 



