b. Elimination of problems related to electrical connections 

 to the surface 



c. Freedom of movement of the vessel during the sounding 

 operation 



d. No restriction on the number of releases that could be made 

 in a given interval of time 



Disadvantages and problems of such an instrument would be: 



a. Requirement for deviation by ship from its course to effect 

 recovery unless instrument is inexpensive enough to be 

 expendable. 



b. Difficulty in locating and recovering instrument 



c. Interference from biological noises 



C. Depth Triggering Device 



There seems to be little immediate prospect of obtaining an instrument 

 that will determine salinity in situ to the accuracy required in deep 

 oceanographic work. A possible interim means of speeding up the 

 collection of data now obtained by Nansen bottles and reversing 

 thermometers is a multiple sea sampler precisely triggered by a 

 vibrating wire transducer, or other good depth element. To further 

 speed up this operation, temperature could be sensed continuously 

 by a thermistor and recorded, together with depth, aboard ship. 



The major unsolved problem in this system is locating or designing 

 something to trigger the bottles with the precision required. Such a 

 device could be designed either to trigger automatically at the standard 

 depths, or it could be designed for manual triggering from deckside 

 at the discretion of the oceanographer observing the temperature- 

 depth record. For programmed triggering, sensitive tuning forks or 

 circuits might be used; for manual triggering, an electrical or acoustic 

 signal could be transmitted to the device over the cable or through 

 the water. 



A simple means that should be investigated for determining the 

 depth of a free-falling device is an impeller such as that used by 

 Hakon Mosby as early as 1942. Such an impeller also might be adapted 

 as a depth triggering device. 



Encl. (2) to Code 5401-BEO/bah memo of 23 Jul 1958 



B-9 



