The nonmagnetic assembly consisted of a cutting shoe, flapper valve and spacer (in place of the 10-finger core catcher), and two 3.3-m nonmagnetic APC barrels. Before coring, this experimental assembly and a standard assembly were placed in chucks and the magnetic fields within the shoes measured. The measurements were made using the Walker Scientific Inc. MG5D Hall probe used in previous experiments (Fuller and Garrett, 1998). Field measurements were made immediately below the cutting shoe, in the assembly beyond the cutting shoe, and into the lowermost APC barrel. The results are shown in Figure F2. The strongest field was observed at the cutting surface of the standard cutting shoe, which reached 2 mT. Other fields in the standard shoe and all the fields of the nonmagnetic shoe were close to the background field in the region below the chucks.