The expedition of Messrs. Lewis and Clarke for exploring the river Missouri and the best communication from that to the Pacific Ocean has had all the success which could have been expected. They have traced the Missouri nearly to its source, descended the Columbia to the Pacific Ocean, ascertained with accuracy the geography of that interesting communication across our continent, learnt the character of the country, of its commerce and inhabitants; and it is but justice to say that Messrs. Lewis and Clarke and their brave companions have by this arduous service deserved well of their country.