CONTENTS OF PART I 
PAGE 
Acknowledgment x i 
Introduction :{ 
Data used and acknowledgments .", 
Methods used in and scope of this investigation 
Outcome of the investigation 7 
Order of presentation s 
Final form of observation equation used for determining evaporation s 
Meteorological stations near Lakes Michigan-Huron and Superior 10 
Inflow into Lake Michigan-Huron (/ 3 ), and outflow from Lake Superior (I4) 11 
Outflow from Lake Michigan-Huron (/*) 12 
Rainfall on the Lake (7 2 ) 13 
Rainfall on land drainage area adjacent to Lake (Related to I c ) 13 
First approximate values of I? for Lakes Michigan-Huron and Superior 16 
Value of I c for Lake Michigan-Huron 19 
Value of Ic for Lake Superior 19 
Rise in the mean surface of the whole lake (A) 19 
Barometric points for Lakes Michigan-Huron and Superior 19 
Hourly barometric effects 19 
Changes in daily barometric corrections 21 
Method of computing daily barometric correction 22 
Wind effects 22 
Examples of computation of known quantities in the observation equation, Equation (1) 25 
Example of computation of e, Lake Michigan-Huron 25 
Example of computation of ( tttt; — x ), Lake Michigan-Huron 29 
Example of computation of 1 3, Lake Michigan-Huron 30 
Example of computation of h, Lake Michigan-Huron 31 
Example of computation of /», Lake Michigan-Huron 32 
Example of computation of h, Lake Michigan-Huron 33 
Example of computation of daily barometric correction 33 
Example of computation of wind correction 43 
Elevations at Milwaukee, Harbor Beach and Machinaw for June to Sept. 1910, corrected for 
wind and barometric effects 44 
Computation of absolute term, I, in observation equation (1), for Lake Michigan-Huron 51 
List of observation equations of the form of equation (1), Lake Michigan-Huron 73 
Normal equations and values of the unknowns from the two final least-square solutions for deter- 
mining Ei and E 2 80 
Principal facts from the two final evaporation solutions 81 
Comparison of computed evaporation from Lake Michigan-Huron with directly observed fall 
of lake surface, corrected for the various influences 84 
The residuals from Solution Vt 85 
Results from Solution BB 4 , Lake Superior 90 
Best values of x in the expression ( tk{\~ x ) 90 
First approximation to minimum winds which affect evaporation 93 
Other evidence in favor of the adopted form of the evaporation formula 98 
Evaporation is a linear function of the wind velocity for winds above 10.8 m. p. h 99 
Run-off into the Lake 102 
Variable part of run-off into Lake Michigan-Huron 102 
Example of computation of n, r 2 , r 3 , . . . r 6 104 
Example of observation equations for determination of evaporation and run-off 110 
Final normal equations for Solution V\, Lake Michigan-Huron Ill 
Variable part of run-off into Lake Superior 112 
Constant part of run-off into Lake 'Michigan-Huron 117 
Constant part of run-off into Lake Superior 118 
Entanglement between constant part of run-off and evaporation 118 
Effect of variable part of run-off on derived values of Ei and E 2 118 
Summary of general conclusions to Part 1 119 
v 
