INDEX. 



Abbreviations, list of, used in refer- 

 ences, 14 

 Amount of ruin in any day, 140 

 Annual fluctuation in rain-fall, 124 

 Autumn, 'distribution of rain in, 123 

 Average number of days of rain during 

 a year, 141 



Basins of supply of rain, 121 

 Bessel's circular function, 124 



Causes of annual fluctuation, 138 

 Comparison of annual amounts at three 



stations, San Francisco, 143 

 Coast survey, authority for latitudes 



and longitudes, 13 

 Construction of rain-charts, 120 

 Copiousness of rain nearly the same 



through the year, 140 



Davs, distribution of rainy, in year, 

 139 



Diurnal amount of rain-fall, 139 



Diversity of amounts of rain at same 

 place, 143 



Drought, years of, followed by unusu- 

 ally wet years, 155 



Droughts, remarkable periods of in 

 1886 and 1855, 158 



Error, probable and annual sums 

 and means, 144 

 sources of, in observations, 8 

 supposed to be 2 per cent., 8 

 Estraordinary fall of rain at Charles- 

 ton, S. C, 143 



Fluctuation, annual, 124 



in annual rain-fall, Atlantic sea- 

 coast, 155 

 New York, 156 

 Ohio River Valley, 156 

 permanency of annual, 136 

 Formula used for comparisons, 124 



Geographical distribution of rain 



stations and map, 133, 134 

 Groups, for combined series, annual 

 fluctuation, 134 

 of distinctive rain-fall, 127 



Hills have small directive influence 



on rain, 121 

 Hypsometrical map, 123 



Increase of average annual precipi- 

 tation from 1818 to present 

 date, 158 

 of rain since 1835, 155 

 Influences on amount of rain, 121 



Lake system of meteorological obser- 

 vations, 1, 4 

 Laws of fluctuation, 155 



Magnetical Observatory, Toronto, 



meteorological results, 139 

 Maps used, furnished by coast survey, 



120 

 Maximum in summer, 138 



in winter, 138 

 Means, how derived, 13 

 Minimum in autumn, 138 

 in winter, 138 

 in summer, 138 

 Monthly percentage of rain-fall, 137 

 Mountains, have small directive influ- 

 ence on rain, 121 



Normal amount of rain for every 

 month, 136 



Observers (see separate list). 

 Ocean currents, 122 



Percentage, monthly, of rain-fall, 13^ 

 Permanency of annual fluctuation, 136 

 Plates, explanation of, 127 



Rain-gauges, description of and direc- 

 tions for observing, 5 

 at military posts, 5 

 of Smithsonian Institution, 6 

 simplest form adopted and dis- 

 tributed by Smithsonian Insti- 

 tution, 8 

 Relative humidity, 138 



Secular change of the rain-fall, 142 

 Snow-gauges, description of and di- 

 rections for observing, 5, 6, 8 



Spring, distribution ef rain in, 123 



Successive means, graphical represen- 

 tation, 156 



Summer, character of distribution of 

 rain in, 122 



Stations (see separate list) 



Sun-spots, connection of with rain- 

 fall, 158 



Tables, for series of years, 85 



Type curves of rain-fall — 



I. Atlantic sea-coast from Portland 



to Washington, 127 



II. Hudson River Valley, Vermont, 



Northern and Western New 

 York ; from Newburg to Bur- 

 lington, and from Hanover to 

 Fredonia, 128 



III. Upper Mississippi River, from 



Fort Madison, Southern Inwa, 

 to Fort Ripley, Central Min- 

 nesota, and including part of 

 Wisconsin, 130 



IV. Ohio River Valley ; from Alle- 



ghany Arsenal, Western Penn- 

 sylvania, to St. Louis, East- 

 ern Missouri, 130 

 V. Indian Territory and Western 

 Arkansas, Forts Gibson, Smith 

 and Washita, 131 

 VI. Lower Mississippi and Red Ri- 

 vers ; also Kentucky, Natchez, 

 Vicksburg, Washington, Ar- 

 kansas, and Springdale, Ky , 

 131 

 VII. Mississippi Delta, and Gulf 

 coast of Alabama and Missis- 

 sippi, New Orleans, Baton 

 Rouge, Mt. Vernon Arsenal, 

 132 

 VIII. Southeastern coast of the United 

 States, Virginia to Florida, 

 132 

 IX. Western coast of United States, 

 from Bay of San Francisco to 

 Puget's Sound, 133 

 X. Alaska, as observed at Sitka, 

 133 



Uniformity of average daily precipi- 

 tation, 141 



Winds, influence of, 122, 123, 138 

 Winter, character of distribution of 

 rain in, 122 



( 175 ) 



