In a long and interesting letter to Mr.Harrison, then governor of Virginia, he detailed the advantages which might be derived from opening the great rivers, the Potomac and the James, as high as should be practicable.

After stating with his accustomed exactness the distances, and the difficulties to be surmounted in bringing the trade of the west to different points on the Atlantic, he expressed unequivocally the opinion, that the rivers of Virginia afforded a more convenient, and a more direct course than could be found elsewhere, for that rich and increasing commerce.

This was strongly urged as a motive for immediately commencing the work.
But the rivers of the Atlantic constituted only a part of the great plan he contemplated.

He suggested the appointment of commissioners of integrity and abilities, exempt from the suspicion of prejudice, whose duty it should be, after an accurate examination of the James and the Potomac, to search out the nearest and best portages between those waters and the streams capable of improvement, which run into the Ohio.

Those streams were to be accurately surveyed, the impediments to their navigation ascertained, and their relative advantages examined.
The navigable waters west of the Ohio, towards the great lakes, were also to be traced to their sources, and those which empty into the lakes to be followed to their mouths.