compensation subsystem to generate a region within the aircraft 

 wherein the effects of the magnetic field of the aircraft are minimized; 

 (4) flight control subsystem to provide autopilot control signals to 

 permit making good a predetermined survey track; (5) computer 

 subsystem to integrate the subsystem elements, provide read-in and 

 read-out functions, provide fail-safe operation, and permit alternate 

 modes of operation under certain failure conditions; and (6) recorder 

 subsystem to provide a permanent record of all vital survey data. 



g. Support the development of precise, absolute total field 

 magnetometers for airborne applications. 



2. Marine geomagnetic surveys 



It is recommended that the Hydrographic Office: 



a. Continue work on the improvement and simplification of the 

 nuclear precession magnetometer and towing system. 



b. Support development of the rubidium vapor magnetometer 

 for both total field and gradiometer operation. This instrument will 

 be useful both for shipboard surveys and for fixed location, temporal 

 variation measurements. 



c. Fully exploit the movements of survey ships under the control 

 of the Hydrographer by employing towed total field magnetometers 

 routinely. 



d. Support an investigation of more efficient data reduction 

 and presentation procedures and instrumentation. 



3. Land measurements 



It is recommended that the Hydrographic Office support the 

 development of compact, portable instruments for field measurements 

 of magnetic field direction and intensity. 



I. SELECTED REFERENCES 



XIV- 1. SCHONSTEDT, E. O. and IRONS, H. R. NOL Vector Airborne 

 Magnetometer Type 2A. Transactions , American Geo ph ysical 

 Union , vol. 36, no. 1, p. 25-41, February 1955. 



XIV- 1 1 



