SOUNDINGS CARRIED OUT WITH THE SONIC 

 DEPTH FINDER 



As a result of action on the part of the Interdepartmental Board on 

 Ice Patrol at its regular meeting in the early part of 1924 one of the 

 ice patrol ships, the Tampa, was equipped with a sonic depth finder 

 of the United States Navy type. The main purpose of the board in 

 having this apparatus installed was to test the practicability of 

 locating icebergs by sonic means. A secondary object was to gain 

 a more accurate knowledge of the bottom contour and consequently 

 of the circulation in the ice regions. An account of the experimental 

 work on icebergs in 1925 and the hydrographical soundings then taken 

 are contained in the report of that year, Bulletin No. 13, page 45. 

 No further work in connection with sound experiments on bergs was 

 attempted in 1926. Arrangements, however, were made whereby a 

 member of the United States Navy sound course at the New London 

 school was detailed to the Tampa for the ice patrol. A program was 

 drawn up to take as many soundings as practical to gain further 

 material for a more accurate mapping of the bottom of the ice regions 

 south of Newfoundland than is yet possible, and this work ought to 

 be continued in the years to come. In accordance with the foregoing, 

 a sounding was taken every hour, 8 a. m. to 10 p. m., while the lampa 

 was on duty this year with the result that a total of 465 observations 

 were made. 



In connection with this work a chart was constructed (fig. 9, p. 49) 

 to include the ice regions south of Newfoundland showing by zones the 

 velocity of sound after corrections had been made for the influences 

 arising from pressure, temperature, and salinity. The distribution of 

 salinity and temperature in the water mass in the ice regions is quite 

 accurately known from the many oceanographic observations which 

 have been compiled by the ice patrol. The correct velocity of sound 

 in a water column of given temperature, salinity, and pressure is found 

 by reference to very useful tables compiled by Heck and Service. 

 (U. S. Coast and Geodetic Survey, Special Publication, No. 108.) 

 The range of soundings made was from 23.5 fathoms to 2,850 fathoms. 

 The list follows with date, hour, and latitude and longitude. 



(49) 



