抄録
For the purpose of taking photographs of lightning flashes, a photographic instrument with a wide visual angle was constructed by the present writer. Ten Leica cameras were so attached along a vertical steel rod that a lightning occurring in any direction might be caught by some one of the cameras. The visual angle is 360° in this case. The steel rod was rotated with a motor. In this way eighteen lightnings appearing at distances smaller than 3km, as well as many others more distant, were photographed. Contrary to the observations of Schonland, the leaders of the first strokes showed no stepped structure. Some of them were continuous like dart leaders and others were composed of several fore-discharges which resembled those occurring in the long sparks produced in the labolatory. One of the leaders showed a band-like structure. It started from the middle point of the lightning path and propagated in both the upward and downward directions. Two examples of upward branching were obtained, but they were found to be different in nature from the ordinary downward branching. Various interesting phenomena caused by space charge below the cloud were observed. Short lightnings streching out into the clear sky from the rim of the cloud were photographed, and it is supposed that they ended in the space charge outside the cloud.
