抄録
As the second step in the approach to the final aim that was related in the previous report1), a series of model experiments of the purse seine was made, with the purpose of knowing the sinking movement of the bottom margin of the net. The model gear which was reduced to 1/250 to the full scale was made based on TAUTI's principle2) (Table 1, 2 and 3). This model net was laid out in the standing water through a circular frame (Figure 1), and the sinking appearance of its lead line was observed and photograghed by the use of a stroboscopic illumination (Plate 1).
As the results of this experiments, it was supposed that the sinking of the bottom margin is in a uniform motion at the eary stage and that in the case of this type of gear, the pursing operation is begun when the bottom margin has sunk at the depth of about 15 fathoms (Figure 4). A few practical examples of records of echo sounder, endorsing the above results, were added (Plate 2 and 3).
