Abstract
1. From the observations of swells made by ships, followingl results were obtained. Seven typhoons, 73 synoptic charts, and 1193 observations of ships were picked up as the data.
2. Within the typhoon, there are two kinds of swells, one progresses according to the wind, the other propagates from the center of typhoon to radial direction.
3. The swells of the first kind, which progress according to the winds, exist in every typhoon, but the swells of the second kind, which propagate from the center, exist only in one of seven typhoons.
4. The oscillation of the atmospheric pressure within the central part of the typhoon will cause the swells of the second kind. Most of the swells, caused by winds, run along the wind-direction within the typhoon-area.
