Simultaneous photographs, taken in two perpendicular directions, have been obtained of long sparks in various gases at 1‐atmosphere pressure. The experiments were undertaken in order to decide whether the localized afterglows, noticed as long streaks in rotating mirror spark photographs, were caused by some discharge mechanism or by purely geometrical effects resulting from the tortuous nature of the spark channels. The results show that the second explanation is not feasible. Some qualitative interpretations of the effects are given.