An electrocardiographic study using squirrel monkeys indicates that strong magnetic fields have a marked effect on the electrical dipole of the mammalian heart. The effect may result from the pronounced influence of strong magnetic fields on electrical processes in living matter, according to the investigators, James C. Knepton Jr., MS, and Dietrich E. Beischer, PhD, of the US Naval School of Aviation Medicine, Pensacola, Fla. Reporting at the 35th Annual Scientific Meeting of the Aerospace Medical Association at Miami Beach, the authors pointed out that their conclusions are drawn from pioneer abservations. No previous experiments were known to them when they undertook their work with four squirrel monkeys and a magnet having a field strength of 70,000 gauss in its center. They said that this study with subhuman primates was based on the assumption that human beings may eventually be similarly exposed to powerful magnetic fields for relatively long periods