First meteorological map, charting the directions of trade winds and monsoons. Information was collected from navigators familiar with ocean transits, and also from his own tropical experience on St. Helena (1677–1678). On the map, rows of brief lines show the course of the winds; the sharp ends of those lines point to wind sources. Where winds go back and forth, notably in the monsoon-prone area of the Indian Ocean, the lines are thicker than elsewhere and point both ways.