Fig. 6 Left-sided fortification spectrum of migraine. Illustration by Dr. Hubert Airy of his own scotomas. A bright stellate object (A) appeared suddenly below and to the left side of fixation (o). It rapidly enlarged, first as a circular zigzag, but on the inner side the zigzag was faint (B); as arc increased in size, it was broken centrally (C). In D, original circular outline had become oval. Rectangular lines that made up the fortification spectrum became longer as the process extended peripherally. When spectrum had extended through greater portion of the field (E), upper portion also began to expand (F). At this time the lower part of spectrum disappeared. The phenomenon ended in a whirling focus of light (G) 20 minutes after it began. At this time a headache appeared on the right side. (Gowers WR: Visual sensations in migraine. In Subjective Sensations of Sight and Sound: Abiotrophy and Other Lectures. London: Churchill, 1907)