This Historical Research is one of the most valuable works that have been called out by the existing Rebellion. It is a thorough and candid exposition of the opinions of the founders of the Republic on negroes as slaves, as citizens, and as soldiers, and has done more, perhaps, than any other single essay to form the public opinion of the present time in respect to the position that the negro should rightfully hold in our State and our army. It has, therefore, and will retain, a double interest, as exhibiting and illustrating the opinions prevalent during the two most important periods of our history. It was first printed, several months since, for private distribution only. More than a thousand copies were thus distributed by its public-spirited author. By this means the attention of persons in positions of influence was more readily secured than it could have been, had the essay been published in the ordinary way. The manner in which the research was conducted, the evidence afforded by every page of the author's conscientious labor, impartial selection, and exhaustive investigation, won immediate confidence in his statements, while his obvious candor, fairness of judgment, and love of truth secured respect for his conclusions. The interest excited by the work extended to a wider circle than could be satisfied by any private issue, while its value became more and more evident, so that, after its publication in the Proceedings of the Massachusetts Historical Society, the permission of the author was obtained by the New-England Loyal Publication Society to issue the work in a form for general circulation. We are glad to assist, by our hearty commendation, the extension of the influence of this essay. It forms, as now issued, a handsome pamphlet of two hundred pages, with a full Table of Contents and a copious Index, and is for sale at a price which brings it within the means of every one who may wish to obtain it. It is a book which should be in the reading-room of every Loyal League throughout the country, and of every military hospital. Editors of the loyal press should be provided with it, as containing an arsenal of incontrovertible arguments with which to meet the false assertions by which the maligners of the negro race and the supporters of Slavery too often undertake to maintain their bad cause.