If we were to single out one from the multitude of official papers prepared by Mr. Clay during his secretaryship, as evincing the most ability and skill, it would be the letter of instructions to Messrs. John Sergeant and Richard C. Anderson, delegates from the United States to the congress at Panama, convened at the request of the republics of Colombia, Mexico, and Central America, whose representatives were also present. The object of this congress was not very definitely stated in the request for it, and, before appointing delegates, Mr. Clay endeavored to ascertain the nature and extent of the subjects upon which they would deliberate, and the powers with which it would be proper to clothe them. This object, though not precisely ascertained, was presumed to be honorable; indeed, the convention was believed to have been suggested by the declaration of president Monroe, that, in case of any interference of any of the allied powers, in the contest between Spain and her former colonies, the United States would not remain an indifferent spectator. This declaration very naturally led the republics before mentioned, towards whom the Holy Alliance maintained a hostile attitude, to seek the cultivation of those amicable relations with the United States, which would secure their aid, in case it should be desired. In Mr. Clay’s letter of instructions, the delegates were authorized to treat of peace, friendship, commerce, navigation, maritime law, neutral and belligerent rights, and other subjects of mutual interest. Subjoined, is an extract from this able document.