To the experienced writer, who might otherwise regard the completion of so vast an undertaking within so apparently limited a period as indicative of work superficially done, I would say that this History was begun in 1869, six years before the publication of _The Native Races_; and although the earlier volumes of the several divisions I was obliged for the most part not only to plan and write, but to extract and arrange my own material, later I was able to utilize the labors of others. Among these as the most faithful and efficient I take pleasure in mentioning Mr Henry L. Oak, Mr William Nemos, Mr Thomas Savage, Mrs Frances Fuller Victor, and Mr Ivan Petroff, of whom, and of others, I speak at length elsewhere. Of my methods of working I need say but little here, since I describe them more fully in another place. Their peculiarity, if they have any, consists in the employment of assistants, as before mentioned, to bring together by indices, references, and other devices, all existing testimony on each topic to be treated. I thus obtain important information, which otherwise, with but one lifetime at my disposal, would have been beyond control. Completeness of evidence by no means insures a wise decision from an incompetent judge; yet the wise judge gladly avails himself of all attainable testimony. It has been my purpose to give in every instance due credit to sources of information, and cite freely such conclusions of other writers as differ from my own. I am more and more convinced of the wisdom and necessity of such a course, by which, moreover, I aim to impart a certain bibliographic value to my work. The detail to be encompassed appeared absolutely unlimited, and more than once I despaired of ever completing my task. Preparatory investigation occupied tenfold more time than the writing. * * * * *