VI CONTENTS. 



3. Alluvial Soils Page 128 



4. Adaptability of Iowa Soils for the growth of forest 



trees 129 



5. Origin of the Prairies 132 



6. Forest Trees 134 



CHAPTER IV.-CLIMATE. By T. S. Parvin. 



1. Temperature:— (1) Monthly and annual mean 



Temperature at three hours daily observations, 

 7 A. M., 2 and 9 P. M. (2) Monthly and annual 

 maximum and minimum temperatures. (3) Va- 

 riations of the annual mean temperatures. (4) 

 Extreme means of monthly temperature, and the 

 annual fluctuation of temperature. (5) Tempe- 

 rature of the Seasons. (6) Times of the highest 

 and lowest temperatures, and the dates of the 

 Spring and Autumn months nearest to the 

 annual mean , 142 



2. Winds : — (1) Prevailing Winds of each month from 



each of the four quarters of the horizon. (2) 

 Winds of the Seasons. (3) Relative frequency 

 of each wind throughout the year ; and also for 

 Summer and Winter 149 



3. Rain and Snow: — (1) Number of days rain and 



snow for each month throughout the year. (2) 

 Monthly and annual quantity of rain, (and snow 

 reduced to water) in inches. (3) Monthly and 

 annual quantity of snow. (4) Total quantity of 

 rain for each season. (5) Distribution of rain 

 throughout the seasons. (6) Relation of rain to 

 the direction of the wind throughout the year ; 

 and also for the Summer and Winter 152 



4. Weather: — (1) Monthly and annual number of 



clear, variable, and cloudy days. (2) Relation of 

 clear weather to . the direction of the wind 

 throughout the year ; and also for summer and 

 Winter 158 



5. Frost and Ice : — Earliest and latest frost, disappear- 



ance from the ground, etc., etc 161 



6. Flowering of fruit trees : — Times of flowering of 



fruit trees 162 



7. Mississippi River : — Dates of opening and closing, 



and number of days closed, for 31 years at Muscatine 163 



