INDEX. 



Abbreviations, list of, used in refer- 

 ences. XX 

 Amount of rain in any day, 210 

 Annual fluctuation in rain-fall, 194 

 .'Vutumn, distribution of rain in, 193 

 Average number of days of rain during a 

 year, 211 



Basins of supply of rain, 1 89 

 Bessel's circular function, 194 



Causes of annual fluctuation, 208 

 Comparison of annual amounts at three 



stations, San Francisco, 213 

 Comparison of old and new rain-charts, 



188 

 Coast survey, authority for latitudes and 



longitudes, xix 

 Construction of rain-charts, 187 

 Copiousness of rain neaily the same 



throughout the year, 210 



Days, distribution of rainy, in year, 209 

 Diurnal amount of rain-fall, 210 

 Diversity of amounts of rain at same place, 



213 

 Drought, years of, followed by unsually 



wet years, 225 

 Droughts, remarkable periods of, in 1836 



and 1855, 228 



Error, probable and annual sums and 

 means, 214 

 sources of, in observations, xiv 

 supposed to be 2 per cent. , xiv 

 Exti'aordinary fall of rain at Charleston, 

 S. C, 213 



P'luctuation, annual, 194 



in annual rain-fall, Atlantic sea-coast, 

 225 



New York, 226 

 Ohio River Valley, 226 

 permanency of annual, 206 

 Fonnula used for comparisons, 194 



Geographical distribution of rain stations, 

 and map, 203, 204 



Groups, for combined series, annual fluc- 

 tuation, 204 

 of distinctive rain-fall, 197 



Increase of average annual precipitation 

 from 1818 to present date, 228 

 of rain since 1835, 225 

 Influences on amount of rain, 189, 190 



Lake system of meteorological observa- 

 tions, v, X 

 Laws of fluctuation, 225 



Magnetical Observatory, Toronto, met- 



eorogical results, 209 

 Maps used, 1S7 

 Maximum in summer, 208 



in winter, 208 

 Means, how derived, xi 

 Minimum in autumn, 208 



in winter, 208 



in summer, 208 

 Monthly percentage of rain-fall, 207 



Normal amount of rain for every month 

 2o5 



Observers ^see separate list). 

 Ocean currents, 190 



Percentage, montlily, of rain-fall, 207 

 Permanency of annual fluctuation, 206 

 Plates, explanation of, 197 



Rain-gauges, description of, and direct- 

 tions for observing, xi 

 at military posts, xi 

 of Smithsonian Institution, xii 

 simplest form adopted and distributed 

 by Smithsonian Institution, xiv 

 Relative humidity, 208 



Secular change of the rain-fall, 212 

 Snow-gauges, description of and directions 



for observing, xi, xii, xiv 

 Spring, distribution of rain in, 192 



Successive means, graphical representation, 



226 

 Summer, character of disti'ibution of rain 



in, I go 

 Stations [see separate list). 

 Sun-spots, connection of, with rain-fall, 228 



Tables, for series of years, 103 



Type curves of rain-fall — 



I. Atlantic sea-coast from Portland to 

 Washington, 197 

 II. Hudson River Valley, Vennont, 

 Northern and Western New 

 York ; from Newberg to Burling- 

 ton, and from Hanover to Fre- 

 donia, 198 



III. Upper Mississippi River, from Fort 



Madison, Southern Iowa, to Fort 

 Ripley, Central Minnesota, and 

 including part of Wisconsin, 200 



IV. Ohio River Valley; from Allegheny 



Arsenal, Western Pennsylvania, 

 to St. Louis, Eastern Missouri, 

 200 

 V. Indian Territory and Western Ar- 

 kansas, Forts Gibson, Smith and 

 Washita, 201 



VI. Lower Mississippi and Red Rivers; 

 also Kentucky, Natchez, Vicks- 

 burg, Washington, Arkansas, and 

 Springdale, Ky., 201 



VII. Mississippi Delta, and Gulf coast 

 of Alabama and Mississippi, 

 New Orleans, Baton Rouge, Mt. 

 Vernon Arsenal, 202 

 VIII. Southeastern coast of the United 

 States, Virgmia to Florida, 202 



IX. Western coast of United States, 

 from bay of San Francisco to 

 Puget Sound, 203 

 X. Alaska, as observed at Sitka, 203 



Uniformity of average daily precipita- 

 tion, 211 



Winds, influence of, 189, 190, igi, 192, 



208 

 Winter, character of distribution of rain in, 



191 



( 249 ) 



