48 ECONOMICAL GEOLOGY. 



Since the publication of Vol. VII, an air shaft was sunk at 

 Decatur, the details of which were furnished for publication by 

 Charles Hansel, Esq., resident engineer of the middle division of 

 the Wabash, St. Louis and Pacific Railway. It is published as 

 a correction of the boring made with a common drill before the 

 coal shaft was sunk, a copy of which was published in Vol. VII, 

 page 17 et seq. of these reports. The air shaft is located about 

 half a mile south-west of the coal shaft., near the bluffs of the 

 Sangamon river. The following is a copy in detail of the record 

 kept: 



