Abstract
It is well known that the disc of the sun and moon near the horizon are deformed by the irregularities of stratification of the atmosphere. The author observed the figure of disc of the setting sun twenty-six times during the three years from 1933 to 1935. The disc was observed with a theodorite. Often it was photographed. Variations of the disc are classified into four types (Fig. 2) as follows.
1. Ellipse and plate type.
2. Separation type,
3. Ellipse type,
4. Ellipse and triangle type.
But as in practice the variation of the disc is a complex phenomenon, that these 4 types represent only typical ones.
The disc of a single discontinuous suoface was observed sixteen times in these figures and the one of double discontimuous surfaces was observed three times.
