50 



ECONOMICAL GEOLOGY. 



ing when a shaft has been sunk to the horizon of the coal re- 

 ported, entailing in many cases a heavy loss to the company 

 undertaking the work. With the diamond drill this uncertainty 

 is easily avoided. 



The beds described as flint rock in the air shaft record, are 

 probably hard silicious limestones which are not uncommon in 

 the Illinois coal measures, while beds of true chert (miscalled 

 Hint) are of rare occurrence. 



Two experiments for the developement of coal in Morgan 

 county, were undertaken shortly after the publication of Vol. 

 VII. Both extended to the bottom of the coal measures, and a 

 condensed copy of the two records is herewith given side by 

 side for comparison. The experiment made at Franklin was by 

 a shaft, and that at Waverly by boring. 



Franklin. 



No. Ft. In. 



1. Drift clay 35 



2. Sandstone 25 



3. Coal 9 



4. Fire clay shale etc 131 



5. Limestone 7 



6. Coal 4 C 



7. Fire clay, shale, etc 85 



8. Coal 1 2 



9. Fire clay, shale, etc 40 



10. Coal 2 (i 



11. Fireclay t> 



12. Limestone... 



Waverly. 



Ft. In. 

 Drift clay 25 



Sandstone and slate ... . 17 (i 



Coal 



Fire clay, shale, etc 153 



Limestone 6 



Coal 1 



Fire clay, shale, etc 141 



Coal 3 



Fire clay, shale 55 



Coal 1 



Fire clay 1 



Limestone. . . , 



No. 6 probably the equivalent of the Springfield coal, No. 5 

 of the general section, while the lower seams Nos. 8 and 10 

 represent coals 1 and 2, and No. 12 the upper bed of the lower 

 carboniferous group. 



About the same time a shaft was sunk at Mt. Pulaski in 

 Logan county and one about a mile; northeast of Lincoln in 

 the same county. Of the latter I have been unable to obtain 

 a record, and for that at Alt. Pulaski I am indebted to Mi-. 

 Beard of Springfield under whose supervision the work was 

 done : 



