I am now able to inform you, tho’ I must do it confidentially, that we are at length likely to get the Missouri explored, & whatever river heading with that, leads into the Western ocean. Congress by a secret act has authorised me to do it. I propose to send immediately a party of about ten men with Capt Lewis, my secretary, at their head. if we could have got a person perfectly skilled in botany, natural history, mineralogy, astronomy, with at the same time the necessary firmness of body & mind, habits of living in the woods & familiarity with the Indian character, it would have been better. but I know of no such character who would undertake an enterprise so perilous. to all the latter qualities Capt. Lewis joins a great stock of accurate1 observation on the subjects of the three kingdoms which are found in our own country but not according to their scientific nomenclatures. but he will be able to seize for examination & description such things only as he shall meet with new. he has been for some time qualifying himself for taking observations of longitude & latitude to fix the geographical points of the line he will pass over. but little means are possessed here of doing that; and it is the particular part in which you could give him valuable instruction, & he will recieve it thankfully & employ it usefully. the instruments thought best to be carried for this purpose are a good theodolite & a Hadley. he will be in Philadelphia 2. or 3. weeks hence to procure instruments & will take the liberty to call on you; and I shall be particularly obliged to you for any advice or instruction you can give him. I think it adviseable that nothing should be said of this till he shall have got beyond the reach of any obstacles which might be prepared for him by those who would not like the enterprise. Accept assurances of my sincere esteem & great respect.