I beg leave to trouble you with the inclosed for Captain Lewis, they do not include many points, because his instructions have really anticipated every thing which occurred to me, & of course admitted of no additions but in detail. I have also avoided several subjects which I expected would be fully detailed by Dr Barton, as being particularly within those departments of Science to which he has devoted himself.

If the expedition should go on without any change in the original plan, in consequence of the late happy events respecting Louisiana, might not Mr Lewis derive some benefit from Monsieur Pirroux or Pierous, a Gentleman who applied to you when Secretary of State respecting an emigration which he wished to effect from Philada to the Spanish Main. He had been Governor (under Spain) of a fort near the mouth of the Missouri & appeared to know more of the trade & navigation of that River than any person I have seen. He said (so long ago as 1792) that the Canada Traders supplied the Indians on the upper parts of the Missouri with goods. If you think it proper to write to him I believe the letter would be very useful to Mr Lewis.   What is the real direction of the Missouri? ’till the publication of McKenzie’s book I believed it to be nearly west, & if I am not mistaken M. Pirroux spoke of it in the same way for 2000 miles of its extent—but McKenzies account is Confirmed by the Gentleman who gave the account of the Wild Sheep, in his narrative he mentions the Missouri as existing no great distance from the Saskatchevine river. I shall write this day to Mr Peter Pond (who is mentioned by McKenzie) on the subject, he lives in Connecticut & I believe will give any information in his power without any particular explanation respecting the reason for asking it.

I cannot conclude this letter without offering you my most sincere & cordial Congratulations on the very happy acquisitions you have made for our Country on the Missisippi—Altho no one here appears to know the extent or the price of the cession, it is generally considered as the most important & beneficial transaction which has occurred since the declaration of Independence, & next to it, most like to influence or regulate the destinies of our Country—I believe that allmost all impartial people here, who take the pains to think for themselves, consider the British reasons for the war as very slight—

With the greatest respect I am your affectionate friend