SIR. In answer to your letter of the 22^d Inst. I with pleasure observe that alth'o the two exploring expeditions you have performed were not previously ordered by the President of the U. S. there were frequent communications on the subject of each, between Gen^l. Wilkinson & this Department, of which the President of the U. S. was aquainted from time to time, and it will be no more than what justice requires to say, that your conduct in each of those expeditions met the approbation of the President; and that the information you obtained and communicated to the Executive in relation to the sources of the Mississippi & the natives in that quarter and the country generally as well on the uper Mississippi as that between the Arkansas & the Missouri, and on the borders of the latter extensive river to its source, and the adjacent countries, has been considered as highly interesting in a political, geographical & historical view. And you may rest assured that your services are held in high estimation by the President of the U. S.; and if opinion of my own can afford you any satisfaction I can very frankly declare that I consider the public very much indebted to you for the enterprising persevering and judicious manner in which you have performed them. [No signature.] To the above Pike made reply at once: WASHINGTON CITY 26 Feby 08 SIR! Suffer me to offer through you, to the president of the United States the effusions of a Heart impress'd with Gratitude for the very honarable testimonial of his approbation received by the Medium of Your Communication of the 24 Inst. The Confidence of the Executive, and the respect of our fellow Citizens, must be the grand desiderata of every man of Honor, who wears a sword in the republican Armies of the United States; to acquire which has been the undeviateing pursuit of the earliest part of my life, & shall mark the colour of my future actions. Suffer me to add Sir! that I feel myself deeply impressed by the Sentiments of personal respect and consideration with which you was pleased to Honor me--and shall always be proud to be considered as one who holds for your person and character Sentiments of the Sincerest Respect & Esteem I am Sir Your ob Sert [Signed] Z. M. PIKE Capt The Hon^l. HEN. DEARBORNE Sec War Dep^t.