139 



Wabash Studies. V. A Topographic Map of the 

 Terre Haute Area. 



Charles R. Dryer. 



The west sheet, co\'ering au area about tive miles square, was pre- 

 sented to the Academy iu 1909 and a poor photographic copy of it was 

 published in the Proceedings for that year. The east sheet, covering an 

 area six l)y seven miles, is now completed. The two sheets cover a strip 

 five to six miles wide north and south and twelve miles long east and 

 west extending across the Wabash valley. The original draught and trac- 

 ing are on a scale of six inches to the mile and the contour intervals are 

 five, ten and twenty feet, according to the relief. The datum planes used 

 for the west sheet were the levels of the Vandalia and Big Four railroads. 

 After that was completed the United States Geological Survey established 

 bench marks in the area which were used for the east sheet, although 

 found to be 3.65 feet above those of the west sheet. 



On the east sheet levels were run with a dumpy level along east-west 

 lines one mile apart and the intervening spaces were filled in with a hand 

 level used on a staff. The levels of the city engineer's office reduced to 

 U. S. G. S. datum, were used wherever available. The work was all done 

 by students of the Department of Geography and Geology of the Indiana 

 State Normal School. In all about forty different persons worked upon it 

 during periods varying from six weeks to thirty-six weeks each. Of 

 these Melvin K. Davis and Garl H. Barker became the most proficient, and 

 to them was assigned the plotting and final draft of the map. 



The map is not good enough for sewer, drainage or hydraulic work, 

 but would be of some value for highway and railroad location. For geo- 

 graphic and geological purjjoses it is far better than none. Its final dis- 

 placement by a better one will not destroy the values of the experience 

 olitained by its makers or the facility it affords for general field work. 



