During my absence on this expedition, there were some things in my correspondence that require notice. Gen. Cass had been transferred to the War Office at Washington. He writes to me from Detroit (July 22d): "Very much to my surprise I have found myself called to another sphere of action. The change I am afraid will be not less unfavorable to my health and comfort than it certainly is adverse to my pecuniary interest. But I am forced by irresistible circumstances to accept the appointment. I have no time to detail these now. When I next have the pleasure of meeting you, I will fully lay them open to you. You will then see and say that no other choice was before me."

Gen. Eaton, the former incumbent, goes out as minister to Spain. The most important aspect is, perhaps, that we shall have a new governor, under whose rule we shall be happy, if he does not rashly derange Indian affairs in a too eager zeal to mend them. For a long and eventful era Gen. Cass has presided as an umpire between the Indian tribes and the citizens. His force and urbanity of character have equally inspired the respect of both. He has equally secured the confidence of every class of citizens in a wise civil administration of affairs. He has carried the territory from a state of war and desolation, which it presented at the close of 1815, when the whole population was less than three thousand souls, to a state of sound prosperity, which, in a few years, will develop resources that must class us one of the first of the Lake States.

July 26th. The Rev. Absalom Peters, Sec. Home Miss. Society, holds out the prospect of bringing our remote position, at the foot of Lake Superior, within the pale of the operations of that society. He views and describes a graduate of Dartmouth College, who may, probably, be induced to venture himself on this frontier. He asks: "Please to say whether you desire such a man as I have described? Will it be best for him to go this fall, or wait until next spring? How much can you raise for his support? How much will be necessary to sustain him and his family with suitable economy? What will be his peculiar trials?"

Aug. 23d. It is announced that Mr. Geo. B. Porter, of Lancaster, Penn., is to be the new governor.

Oct. 4th. The last mail brings me a letter from an early and esteemed friend, a Prof. in the Med. Col. at New York, offering me congratulations on the moral stand recently taken by me. Approvals, indeed, of this act reach me from many quarters. The way seemed open, with very little exertion on my part, to run a political course. But my impressions were averse to it. There is so much of independent honest opinion to be offered up by politicians--such continual calls to forsake the right for the expedient--such large sacrifices to be made in various ways to the god of public opinion, that a political career is rather startling to a quiet, unambitious, home-loving individual like myself, one, too, who is largely interested in other studies and pursuits, the rewards of which are not, indeed, very prompt, very sure, nor very full; but they are fraught with gratifications of a more enduring kind, and furnish aliment to moral conceptions which exalt and purify the soul.

Dr. Torrey also alludes, in the same letter, to my recent journey in the Indian country: "I am anxious to make some inquiries of you concerning your expedition to the Falls of St. Anthony, &c. Though your principal object was more important, perhaps, than natural science, I hope the latter was not entirely neglected. I know that you have heretofore devoted as much of your attention as possible to the observation of natural objects, and the preservation of specimens, and your last expedition was through a country well deserving of your highest exertions. I know that part of it is the same as that explored while you attended Gov. Cass, many years ago; but much of the ground, if I am rightly informed, is new. You know that I have long devoted much of my time to the study of N. American botany, and that I am collecting materials for a general Flora of our country. Now, my dear sir, if you or Mr. Houghton (the young gentleman whom, I am informed, accompanied you) have made any collections in botany, I should esteem it a peculiar favor to have the examination of the specimens.

"Our Lyceum prospers. We have removed to the N.Y. Dispensatory, a new building lately erected in White Street, where we have excellent accommodations. The Corporation of the city had use for the N.Y. Institution, and nearly all the societies who occupied it have been obliged to decamp. You doubtless have heard of the death of Dr. Mitchell. Dr. Akerly will pronounce his eulogy soon, and probably Dr. Hosick will give a more elaborate account of his life.

"Mr. Cooper now devotes himself to shells and birds. If you have anything rare or new in these departments, we should be greatly obliged to you for such specimens as you can spare.

"Dr. Dekay went to Russia with his father, Mr. Eckford, last summer."

23d. A friend and shrewd observer from Detroit, writes: "You ask how we like our new Governor. Very well. He is a well-informed plain man, unassuming in his manners and conciliatory, always ready for business, and accustomed to do everything en ordre. His wife is a fine-looking agreeable woman, with several pretty well-behaved children."