MESSRS. EDITORS: One of the most difficult things I ever undertook has been to trace the different journeys of discovery of the Spaniards, in the country to which they gave the name of New Mexico; and it would have been impossible to have accomplished this undertaking, but for the assistance of that extraordinary and invaluable collection of maps and books on the subject of America, made with great expense and labor, by Mr. Force, of Washington. Of these difficulties no one can form a just idea who has not made the attempt. It may be proper to state, that the whole country, from the mountains east of the Rio Grande to the Pacific—from about 32° south to 37° north—in consequence of these discoveries, and on account of its great cities, and its numerous and civilized population, was called New Mexico in reference to old Mexico, as New Spain was named in reference to Old Spain. My principal source of information is the work of Gomara, and Hackluyt’s collection of voyages; but I was obliged to consult many other works. In some of the oldest maps, the Colorado of California is called the _Rio Grande del Norte_, and is represented as taking its rise in a great lake to the north east; while the _Rio Grande of the Gulf_, or, as it was called, the North Sea, does not appear. It will be readily seen that this was sufficient to account for much of the confusion and mistakes of the early writers, and of the fruitless attempts to trace the early journeys of discovery. The first journey was that of Marco de Nicia, a friar, accompanied by a small party. He set out from Pitatlan, on the Gulf of California, in latitude 24°, in the year 1539, about twelve years after the conquest. I shall not enter into details. After some days’ travel to the north, through populous countries, he came to Vacupa, where he first heard of populous countries to the north, of the province of Cibola, and of the seven great cities. After reaching, as he supposed, latitude 26°, he found Indians who had no knowledge of christians. He was then about fifty leagues from the Gulf of California. He was informed by these indians of a great plain, about thirty days’ further travel to the north, inhabited by people living in large towns, built of stone and lime, who wore cotton garments, and possessing abundance of gold and turquoises, sometimes called _emeralds_, from the affinity to that precious stone.