I have had the honor of receiving the friendly & obliging letter which you wrote me on the 27th of last month, together with the one enclosed, from Judge Cooper of Pennsylvania, to yourself, of 10th of May: & I feel some anxiety of mind least the tardiness of my reply, to you, may be the cause of procrastinating yours to Judge Cooper much longer than may be agreeable to you. But as I did not reach this from below, till it was entirely too late to consider the interesting proposition you have made me, & to write you the result by the last mail, you will do me the justice to regard this as the earliest reply which it has been in my power to send you.

The selection which you make of me among the numerous persons to whom you no doubt have directed your looks on this occasion, is a circumstance that does me honor; but it is an honorable notice to which I am not entitled. And the friendship which you discover in the style of your letter makes the most agreeable impression on my feelings.

It would be very acceptable to me to enter into the correspondence proposed with Judge Cooper; & doubtless as advantageous as you suppose. But there is a sine qua non, wanting on my part. It is a sufficient knowledge of the science of Mineralogy in general, and leisure to explore the country, & make the requisite collections. In the first I am deficient, & the second I could not promise myself with the least confidence.

When I went to Europe, my health was in too feeble a state to support even the effort of reading, & I found myself in a situation that called for a new source of mental recreation & improvement. There was also a chasm in the little circle of science which I had commenced in America, that was yet to be filled up. France moreover presented to my view, all the branches of Natl History under the aspect of new & captivating splendor. These causes directed my attention to the natural sciences. I attended Mr Delamethrie’s course. I travelled with Mr Maclure over the mountains of auvergne, & the alps, & assisted him to make collections. I bought a small cabinet in Paris, & a box of about one hundred specimens of volcanic substances thrown out by Mount Vesuvius. The book which I read (& that only in part) was Brochant’s Werner. But my health was often so feeble, & my mind was so occupied by an infinite variety of objects, & in short my studies were so subordinate to my main object of travelling, that I found myself on leaving France, only in possession of some elementary notions, & a small cabinet of minerals, respectable enough for a private individual, all of which were valuable only as presenting the means of future improvement.

It was never my object to aim at extensive attainments in Mineralogy. Nor did I feel certain that my future pursuits in America, would afford le isure to indulge the feelings of an Amateur. However I thought I would be provided for every event, & brought my cabinet along.

Since my return, I have become involved in the usual pursuits of Virginians, & my mind has been totally abstracted from natural History. Instead of exploring the country & adding to my collection, I have actually lost a portion of the small stock of knowledge which I brought home with me. Foreseeing the situation in which I should stand for some years at least, & not wishing to act the part of the Dog in the manger, I lent my cabinet of minerals to William & Mary College, & my herbarium to Mr Girardin, not long after I got back to Virginia. The time of the loan has expired, my situation is becoming rather more favorable for such pursuits, & I think of bringing home my little scientific treasures in the course of next spring. But judging from the past, & considering the nature of my pursuits, & the probable consequences to which they will lead, I shall have very little time for mineralogy. Ignorant as I am of the science at this time, & promising myself but little improvement in future, I should be unwilling to enter into an engagement with a man of science at a distance, which to be complied with, would require considerable attention & many & long journies over the country. An additional reason, is that I am already under similar obligat[ions] to some friends, & my inability to comply with them, has cost me severe feelings of regret. Under these circumstances, I have only to request you to refer Judge Cooper to some more suitable character, & to make you my acknowledgments for the compliment you have paid me.