If it was difficult to collect the most ordinary statistical data relative to the interior, it may easily be supposed how much more so it was to obtain information of any interest in a scientific point of view; nevertheless, in this respect, I was not altogether without resources; and the accidental residence of two or three observing and intelligent individuals of our own countrymen in the remotest parts of these widely-spread regions laid open to me sources of information even upon such matters as I little expected. The results of that portion of my correspondence will be found in various parts of this Volume, where I have had the satisfaction of acknowledging my obligations to the individuals from whom they were derived. From the materials to which I have above alluded, and other papers in my possession, my original intention was to have attempted a work of a more extensive nature; but any necessity for this has been since superseded by the publication, which has been commenced by M. de Angelis, at Buenos Ayres, under the auspices of the Government, of an extensive collection of unedited historical documents relative to the provinces of La Plata. In the course of the last three years five folio volumes, and portions of two more, have already appeared, in which not only many of the most interesting of the papers in my own collection are given, but a variety of others throwing great light upon the history and geography of the countries to which they relate[4]. I cannot hesitate to say that it is infinitely the most important and interesting publication which has as yet appeared in any of the new states of Spanish America, to the great credit of the enlightened editor, who has illustrated it with his own learned notes and observations, the fruits of a long study of the history of his adopted country. Upon the appearance of the first volumes I gave up my own design, as a work of supererogation where one so much more valuable was attainable. It became however manifest, as M. de Angelis' work proceeded, that its extent would rather render it available as a book of reference and authority than for general purposes; and, as it was in the Spanish language, particularly so for the general purposes of English readers. I was again, therefore, induced to resume my task, though with the essential change in its character from my original plan, to the brief and general sketch of the Republic, and of the progress of geography in that part of the world during the last 60 years, which now appears; referring those who desire more detailed information to the invaluable collection of original memoirs now in course of publication by Don Pedro de Angelis: it has been of great use to me in enabling me to complete my own chain of information, as indeed it must be to any one who pretends to give any account of the part of the world of which the documents it contains may be said now to constitute the original and authenticated historical records.