INTEODUCTORY AND HISTORICAL. 651 



Elevation Above Lako 



above Sea. Michigan. 



Black Earth 810 232 



Mazoraanie , 773 195 



Arena 732 154 



Spring Green 722 144 



Lone Rock 704 126 



Avoca 695 117 



Muscoda , 687 109 



Boscobel 667 89 



Wauzeka , 638 60 



Prairie du Chien 619 41 



Finally, it may be said of the elevations, that they are by far the 

 most important and valuable part of the work, inasmuch as they form 

 the ground- work of the whole, and we are entirely dependent on them 

 for definite results. They have been made and computed with the 

 utmost accuracy and care. Lastly, they comprise that portion of the 

 work, which, from its nature, consumes the most time, and makes the 

 least outward show. 



In conclusion, I desire to express my thanks for the hearty co- 

 operation which the survey has met at the hands of the citizens of the 

 Lead region, who have willingly furnished all desired information 

 and statistics, often at no small inconvenience to themselves. 



My thanks are also due to Mr. Allan D. Conover, of Madison, my 

 assistant during the year 1873; to Mr. George Haven, of Minneapolis, 

 Minn., my assistant during the years 1874-1875, who, by the careful 

 discharge of their duties in the field, have contribiited materially to 

 the completeness of the work. 



