It is now determined that I shall go towards the Rocky Mountains at least to the Yellowstone River, and up the latter Stream four hundred miles, and _perhaps_ go across the Rocky Mountains. I have it in my power to proceed to the Yellowstone by Steamer from St. Louis on the 1st day of April next; or to go to the "_Mountains of the Wind_" in the very heart and bosom of the Rocky Mountains in the company of Sir William Drommond Stewart, Baronet who will leave on the 1st of May next also from St. Louis. It has occurred to me that perchance you would like to spare a few months of your life, to visit the great Western Wilderness, and perhaps again prefer going in my Company in preference to that of any other person? Of this of course I cannot Judge without your answer to this. I thought that you would have been in New York long ere this, but not a Word of you has reached any friend of yours here for several months. I have had an abundance of applications from different sections of the country, from Young Gents who proffer much efficiency, etc., but I do not know them as I know you, and if the terms which I am about to propose to you will answer your own views, I wish you to write to me at once so that I may know how to prepare myself for such a Journey, and under such circumstances. Would you like to go with me at any rate? By which I mean, whether by Land, or by Water, and undertake, besides acting towards me as a friend, to prepare whatever skins of Birds or Quadrupeds, I may think fit for us to bring home. The Birds, you might have one half as your own, the Quadrupeds, (should you wish it) you might have a 4th or every 4th specimen of the same species, reserving to myself all that is new or exceedingly rare. I will procure and furnish _all the materials_ for skinning, preparing, and saving whatever we may find in Ornithology and in Mammalia, and in all probability (if you think it absolutely necessary) pay one half your expenses from the time we leave St. Louis until our return to that city. You will have to work hard, of course, but then I trust to that the knowledge alone which you must acquire would prove a sufficient compensation, and as you already know me pretty well, I need not say to you that I am not "hard on the trigger." It will be necessary for you to provide a good double barrelled Gun, and an excellent Rifle, Shot bag, powder flask, &c, a good hatchet, and a sufficiency of clothes for something like a 12 month's Campaign. But if you will write me at once upon the subject, I can give you a more and a better a/c of all my intentions, than is at present necessary. If all goes on as I trust it will go on, we may be back home by Octr. or Novr. next, 1843.