It is only in recent years that the extraordinarily heavy rainfall in portions of the Hawaiian Islands have become a matter of record. In the course of their high-level hydrometric work the engineers of the United States Geological Survey found it necessary to measure the rainfall at a number of points at various elevations up to more than 5,000 feet above sea level.

Cherrapunji, with its annual average rainfall of 426 inches, has been generally cited as the wettest place in the world. In a recent period covering nearly 5 years, Mount Waialeale, elevation 5,080 feet, on the Island of Kauai, Hawaiian Islands, averaged 476 inches of rainfall annually. In this period of 1,782 consecutive days the total precipitation was 2,325 inches—a daily average of 1.30 inches.

Another very striking feature of the rainfall records in the Hawaiian Islands is the great contrast in amounts in stations separated by only a few miles but with considerable differences in altitude or exposure. Six photographic illustrations give an excellent idea of the topography of the country while the two remaining figures show the relative sizes of the special rain gages employed, and the mean monthly rainfall variations.