This is a vintage black and white diagram depicting an aurora borealis observation. The image is labeled 'Fig. 13' at the bottom. The upper portion of the image shows two distinct auroral displays, labeled 'A' and 'B'. Both displays are characterized by vertical, parallel lines, resembling curtains of light. Display 'A' is wider and appears more diffuse, with a slightly curved base. Display 'B' is narrower and more concentrated, with a straighter base. The lines within both displays are closely spaced, creating a dense, textured effect. Below the auroral displays is a circular area representing a ground-level observation point. Within the circle, two small figures of people are visible, seemingly observing the aurora. The circle is surrounded by a textured pattern, possibly representing terrain or vegetation. The background is a dark, speckled field, suggesting a night sky. The overall style of the image is reminiscent of scientific illustrations from the late 19th or early 20th century, with a focus on detailed observation and documentation.