SURFACE RELIEFS. 



429 



tained them directly from the profiles in the offices of the several com- 

 panies. The list is very full, an altitude being given for almost every 

 section line crossed, and of course the figures have a high degree of 

 accuracy. Except where otherwise stated, the railroad grade is al- 

 ways meant. The remaining tables include a number of altitudes, de- 

 termined by the aneroid barometer, which are, of course, approxima- 

 tions only. These are selected from a list of many thousand, and 

 apply almost wholly to Dane, Columbia and Sauk counties, which 

 liave been chosen because in them the conditions of observation were 

 more favorable, reference points having been accessible during near- 

 ly every day's work, and because, also, in this part of the district 

 the mapping of the geological formations required that the observa- 

 tions should be much more numerous, and consequently more accu- 

 rate, than elsewhere. 1 Numerous determinations of altitude were 

 made in the other counties of the district, but, on account of the dis- 

 tance from railroads or other standards, only a few deserve to be list- 

 ed here. The general altitude of any portion of the district can be 

 obtained from the chapters on local details. 



MADISON TO ELEOY, 

 Chicago & Northwestern Railway. 



Place. Altitude. 



East Madison depot 264 



Station 65, J road crossing 266 



" 130 273 



" 175, (summit) 305 



" 262, (summit) 325 



" 277, deep cut, surface 355 



01 r ( surface Catfish marsh 255 



315 '|grade 277 



" 400,..: 285 



A KO i grade 323 



458 ' ] furface 310 



" 520, Waunakee 341 



" 570, 341 



ear? j surface 369 



667 'igrade 395 



" 787, Dane depot 477 



" 900, 365 



; -, MO j surface of creek 233 



1002 'igrade 267 



" 1039, Lodi depot 267 



" 1140, 319 



grade 265 



surface 255 



grade 200 



surface 175 



1200, 

 1300, 



Place. Altitude. 



( bridge. 215 



Station 1360, ] sur. \Vis.riv., low wat. 170 

 ( sur.Wis. riv., highwat. 180 



" 1380, Merrimac depot 215 



1460, 250 



j grade 221 



] surface 178 



" IfiOO f ^ Tade 292 



lUU ' 1 top Devil's Nose 378 



1696, surface 464 



" 1702 429 



1783, Devil's Lake, grade ... 386 



iqna f brid g e 276 



' 8 '} surface 224 



1950, Baraboo depot 284 



Lyons depot 282 



Bloom's depot 300 



Ableman's depot 297 



Reedsburg depot 296 



La Valle depot 316 



Wqnewoc depot 329 



Union Center depot 362 



Elroy depot 360 



2 Stations 100 feet apart, beginning with Eaet 

 Madison depot as zero. 



1 The aneroid determinations of altitude listed here are believed to have a considera- 

 ble degree of accuracy. In many cases the same point was visited on different days, 

 from different directions; and in other cases a second barometer was read half -hourly at 

 a fixed point, whilst observations were being made, tn this latter way it seems possi- 

 ble to attain great accuracy with the aneroid, especially if such suitable and reliable in- 

 struments are used as those made by J. H. Steward, of London. These have a range of 

 onlv 3.000 feet, and show a variation of 5 feet very distinctly. 



