=172. Application of Fitzgerald’s Results to the Croton Watershed.=—The evaporation data determined by Messrs. Fitzgerald and Kuichling are sufficient for all ordinary purposes in the North Atlantic States. In the discussion of the capacity of the Croton watershed Mr. Fitzgerald’s results will be taken, as the conditions of the Croton watershed in respect to temperature and atmosphere are affected by the proximity to the ocean, and other features of the case make it more nearly like the Metropolitan drainage area near Boston than the more elevated inland district near Rochester. If the monthly amounts of evaporation be taken from the preceding table, and if it further be observed that a volume of water 1 square mile in area and 1 inch thick contains 17,377,536 gallons, the following table (Table XI) of amounts of evaporation from the reservoirs in the Croton watershed, including the new Croton Lake, will result, since the total area of water surface of all these reservoirs is 16.1 square miles. TABLE XI. Jan. 0.96 × 16.1 × 17,377,536 = 268,600,000 gallons. Feb. 1.05 × ” × ” = 293,800,000 ” Mar. 1.70 × ” × ” = 475,700,000 ” April 2.97 × ” × ” = 831,000,000 ” May 4.46 × ” × ” = 1,247,900,000 ” June 5.54 × ” × ” = 1,550,100,000 ” July 5.98 × ” × ” = 1,673,200,000 ” Aug. 5.50 × ” × ” = 1,538,900,000 ” Sept. 4.12 × ” × ” = 1,152,800,000 ” Oct. 3.16 × ” × ” = 884,200,000 ” Nov. 2.25 × ” × ” = 629,600,000 ” Dec. 1.51 × ” × ” = 422,500,000 ” ----- -------------- 39.20 Total = 10,968,300,000 ” It will be seen from this table that the total annual evaporation from all the reservoir surfaces of the Croton watershed, as it will exist when the new Croton Lake is completed, will be nearly 11,000,000,000 gallons, enough to supply the boroughs of Bronx and Manhattan at the present rate of consumption for about forty days.