III. DATA PROCESSING 



A. Preliminary Data Processing 



Magnetometer records were scaled at 50-gamma intervals and also 

 at times when maximum and minimum values of magnetic intensity were 

 recorded. Gamma values were obtained by using a scaling template designed 

 for converting magnetometer counts to gammas. 



Precision Depth Recorder traces were scaled directly at 100- 

 fathom intervals and also for maximum and minimun recorded depths. No 

 sound-velocity or other corrections have been applied to the bathy- 

 metric data. 



Magnetic and bathymetric profiles for each of the three ships 

 were constructed using the adjusted survey tracks as base lines. An 

 index to the geographical location of each profile is given in Figure 

 2, Part I (Norwegian Sea - New York), and in Figure 31, Part II 

 (New York - Norwegian Sea) . Profiles in Part I are presented in 

 reverse numerical sequence from west to east to provide a more 

 effective presentation. Adjusted smooth plots of the survey tracks 

 are shown on the upper portions of the profile sheets. 



B. Magnetic Temporal Variations 



The magnetic data were not corrected for temporal variations of 

 the earth's magnetic field; however, records from the magnetic observa- 

 tories at Fredericksburg, Virginia, and Hartland, England, were studied 

 to determine if there were any unusual magnetic disturbances during 

 the Atlantic crossings. 



The records obtained from each observatory were in the form of 

 the 3-hour,' magnetic K-index. Conventionally, the K-index is a digit 



