In its intensity rain varies all the way from the finest drizzle or the sprinkle of occasional drops up to the torrential downpours often known as “cloud-bursts.” Before citing instances of heavy rains, it may be well to remind the reader that an inch of rainfall is equivalent to 101 tons of water per acre, or 64,640 tons per square mile. In the county of Norfolk, England, in August, 1912, a single day’s rainfall brought down 670,720,000 tons of water--more than twice the volume of water contained in England’s largest lake, Windermere. Doubtless this record, for showers of similar extent and duration, has often been surpassed in other countries, including our own, and _a fortiori_ within the tropics. The most remarkable example of a heavy brief shower was recorded at Porto Bello, on the Isthmus of Panama, May 1, 1908, when a fall of 2.47 inches _in three minutes_ was registered by a self-recording rain gauge. An average heavy rainstorm in the eastern United States yields about this amount in twenty-four hours. At Baguio, in the Philippines, forty-six inches of rain fell from noon of July 14, 1911, to noon of the following day--probably a “world record” for twenty-four-hour rainfall. The corresponding record for the United States is 22.22 inches at Altapass, N. C., July 15-16, 1916. Statistics of what the meteorologist calls “excessive rainfall”--i. e., abnormally heavy rain during brief periods--have been collected over the greater part of the world for much more weighty reasons than to satisfy curiosity as to which showers were “record breakers.” Such data are indispensable to engineers in connection with the building of sewers, reservoirs, and dams, and in flood-protection work. Sewers must be made large enough to carry off the “storm water” from the heaviest showers that ever occur in the locality; while, on the other hand, in the absence of rainfall statistics, much money might be wasted in making them larger than necessary. A great flood raises questions as to the intensity of the rainfall that caused it, and the frequency with which similar rains may be expected to occur in the drainage area concerned. The unprecedented floods in the Ohio Valley and adjacent regions in March, 1913, which caused losses amounting to $200,000,000, led to an exhaustive study of the records of storm rainfall in the eastern United States, carried out by the engineers of the Miami Conservancy District. Their report on this subject (published at Dayton, Ohio, in 1917) is probably the most elaborate discussion of the kind hitherto prepared for any part of the world. Of the 2,641 storms investigated, seventy-eight, which covered areas of 500 square miles or more, were found to have had a rainfall amounting to at least 20 per cent of the normal rainfall for a year.