APPENDIX. 285 



III. 



Copy of a letter from Gov. Lewis Cass to Hon. John C. Cal- 

 houn, Secretary of War, dated 



Detroit, September 20, 1820. 



Sir: In examining the state of our topographical knowledge, 

 respecting that portion of the Northwestern frontier over which 

 we have recently passed, it occurs to me that there are several 

 points which require further examination, and which might be 

 explored without any additional expense to the United States. 



The general result of the observations made by Capt. Douglass, 

 will be submitted to you as soon as it can be prepared. And I 

 believe he will also complete a map of the extensive route we 

 have taken, and embracing the whole of the United States, 

 bounded by the Upper Lakes and by the waters of the Mississippi, 

 and extending as far south as Eock Island and the southern ex- 

 tremities of Lakes Michigan and Erie. The materials in his pos- 

 session are sufficient for such an outline, and he is every way 

 competent to complete it. But there are several important 

 streams, respecting which it is desirable to procure more accurate 

 information than can be obtained from the vague and contradic- 

 tory relations of Indians and Indian traders. The progress of 

 our geographical knowledge has not kept pace with the extension 

 of our territory, nor with the enterprise of our traders. But I 

 trust the accurate observations of Captain Douglass will render a 

 resort to the old French maps for information respecting our own 

 country entirely unnecessary. 



I beg leave to propose to you, whether it would not be proper 

 to direct exploring parties to proceed from several of our frontier 

 posts into the interior of the country, and to make such observa- 

 tions as might lead to a correct topographical delineation of it. 

 An intelligent officer, with eight or ten men, in a canoe, would 

 be adequate to this object. He would require nothing more than 

 a compass to ascertain his course, for it is not to be expected that 

 correct astronomical observations could be taken. In ascending 

 or descending streams, he should enter in a journal every course 

 which he pursues, and the length of time observed by a watch. 

 He should occasionally ascertain the velocity of his canoe, by 

 measuring a short distance upon the bank, and should also enter 



