compensated is only important when the salinity- 

 value is a long way from the value at which the 

 bridge is balanced. To insure good stability in 

 the basic oscillator, the amplifiers A]_ and A2 

 have very good phase shift stability and the 

 level of oscillation is controlled by the auto- 

 matic gain control circuit to a level well below 

 overload . 



9. HUEBNER, G. L. , Notes on radio frequency 



salinity measuring equipment at Texas A. & M. 

 College, Publ. 600, National Academy of Sci., 

 National Res. Council, 1958. 



10. GUPTA, S. R. and G. J. HILLS, A precision 

 electrode-less conductance cell for use at 

 audio frequencies, J. Sci . Instruments , 33., 

 313-315, 1956. 



CONCLUSIONS 11. 



It is estimated that the combined stability of 

 the conductivity sensor, the temperature and pres- 

 sure compensating circuits and the electronics 

 will yield a repeatability of ±0.005 parts per 

 thousand and an accuracy of + 0.05 parts per 

 thousand in salinity including both temperature 

 and pressure compensation errors from to 25°C 

 and to 20,000-foot depth. However, the com- 

 pensation errors can be accurately determined 

 and allowed for in the final analysis with a 

 resulting accuracy approaching +0.01 parts per 

 thousand salinity. 



12. 



13- 



11+ . 



15- 



REFERENCES 



1. JONES, G. and G. M. BOLLINGER, The measure- 

 ment of the conductance of electrolytes 



III. The design of cells, J. Amer. Chem . Soc . 

 53, 1+11-1+51, 1931. 



2. HAM0N, B. V., A portable-temperature chlor- 

 inity bridge for estuarine investigations 

 and sea water analysis, J. Sci . Instru . , 33 ; 

 329, 1956. 



BRADSHAW, A. L. and K. E. SCHLEICHER, A con- 

 ductivity bridge for the measurement of l6. 

 salinity of sea water, Tech. Rept. 56-20, 

 Woods Hole Oceanographic Inst., 1956. 

 UNPUBLISHED. 



ESTERS0N, G. L. and D. W. PRITCHARD, C.B.I. 

 salinity-temperature meters, Proc . , Conf. on 

 Coastal Eng . Instruments , Berkeley, Calif., 

 1955) University of California Council on 

 Wave Research of the Engineering Foundation, 

 Berkeley, 260-271, 1956. 



ESTERS0N, G. L., The induction conductivity 

 indicator, Tech. Rept. 1*+, Ref. 57-3, Chesa- 

 peake Bay Inst . , Johns Hopkins University, 

 1957. UNPUBLISHED. 



BROWN, N. L. and B. V. HAM0N, An inductive 

 salinometer, Deep - Sea Res . , 8(l), 65-75; 196l. 



BROWN, N. L., A. L. BRADSHAW and K. E. 

 SCHLEICHER, A recorder for in situ measure- 

 ment of salinity by the inductive method, 

 temperature and depth, Unpublished work under 

 Office of Naval Research Contract 2196-7 at 

 Woods Hole Oceanographic Inst. 



BRADSHAW, A. L. and K. E. SCHLEICHER (private 

 communication) unpublished work in progress 

 on the relationships between conductivity, 

 salinity, temperature and pressure of sea 

 water under Office of Naval Research Contract 

 2196-7 at Woods Hole Oceanographic Inst. 



HAM0N, B. V., The effect of pressure on the 

 electrical conductivity of sea water, 

 J. Mar. Res., 16, 83-89, 1958. 



1+. COX, R. A., The thermostat salinity meter, 



Internal Rept. C2, National Inst, of Oceanog- 

 raphy, 1958. UNPUBLISHED. 



5. WENNER, F., E. H. SMITH and F. M. S0ULE, 

 Apparatus for the determination aboard ship 

 of the salinity of sea water by the elec- 

 trical conductivity method, National Bureau 

 of Standards J. Res ., 5, 711-732, 1930. 



6. JAC0BSEN, A. W., An instrument for recording 

 continuously the salinity, temperature and 

 depth of sea water, Trans. Amer. Inst. 

 Electrical Eng ., 67, 715, 19587 



7. HAM0N, B. V. and N. L. BROWN, A temperature- 

 chlorinity-depth recorder for use at sea, 



J. Sci. Instruments , 35, 552-1+58, 1958. 



8. HARWELL, K. E., Radio frequency salinity 

 instrument, model E, Tech. Rept. 5, Depart- 

 ment of Oceanography and Meteorology, 



A. & M. College of Texas, 1955. UNPUBLISHED. 



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