No. IV. 



Geological Account of the Valley of the Ohio : in a Letter 

 from Daniel Drake, M. D. to Joseph Correa de Serra. — 

 Bead 7th Nov. 1818. 



Cincinnati, Ohio, ist October, 1817. 



Sir, 



I PEAR that you have long since thought me inatten- 

 tive to your polite request, that I should send you a copy of 

 the Vertical Chart which I had sketched of the valley of the 

 Ohio river at this place. But so far from being regardless 

 of your wish, an over anxious desire to gratify it fully has 

 been the cause of my delay. I entertained, till lately, the 

 hope of collecting such facts as would lead to some certain 

 conclusions relative to the epochs and causes of this great 

 excavation ; but constant ill health, and an increase of my 

 ordinary engagements, have left me so small a portion of 

 time for research or reflection on extra-professional sub- 

 jects, that I no longer expect to do more than give you an 

 evidence of my disposition to amuse you. 



Notwithstanding the delay of so many montlis, the gra- 

 phic execution of the present copy is very little better than 

 the original sketch which you saw in Philadelphia. It is, 

 however, I trust, as accurate a representation as the perfo- 

 rations and admeasurements hitherto made at this place will 

 admit. The elevations and projections are of course on 

 different scales ; which gives to the slopes a greater perpen- 

 dicularity than is correct j but of this, and the other effects 



