III. DATA PROCESSING 



The strip-chart record of magnetometer counts is a non-linear 

 inverse function of the earth's magnetic field strength. By 

 means of a special template developed at the Oceanographic Office, 

 the data tapes were scaled directly in gammas. Contour charts of 

 total magnetic intensity (Figs. 2 and 4) were constructed from 

 these scaled data using a contour interval of 50 gammas. Bathymetric 

 contour charts (Figs. 3 and 5) were prepared using a contour 

 interval of 100 fathoms. To show the density of the survey data, 

 a track pattern is overprinted on the bathymetric contour charts. 



Magnetic and bathymetric profiles taken along approximately 

 2600 miles of enroute tracks are presented in Figures 7 through 22. 

 Several of the magnetic profiles are shown together in Figure 6 to 

 illustrate zones of differing magnetic character. For ease of 

 presentation in Figure 6, the earth's regional gradient was removed 

 from the magnetic profiles. 



No corrections to the magnetic data were made for temporal 

 variations of the magnetic field. No sound velocity or other 

 corrections have been applied to the bathymetric data. 



