The Frank system was compared to my modified system in 55 healthy adult men in order to investigate the effect of variation in the antero-posterior distance of the trunk. The modified Frank system described in the preceding paper was investigated in two groups who were divided according to the ratio of antero-posterior to right-left distance. The modified Frank system 1 was applied to group 1, and the modified Frank system 2 was applied to group 2. The following results were obtained: 1. The magnitude of the maximum QRS vector in the modified system increased in the sagittal plane and in space in comparison with that of the Frank system. The direction of the maximum QRS vector was located anteriorly in the horizontal plane and in azimuth, a...