index to the growth of the national library, and the world would have the nearest approach to a register of all literature that, in the absence of any feasible scheme for a universal catalogue by co-operation among public libraries, it seems likely to obtain. Even this more ambitious project might be promoted if public libraries would consent to take the Museum Catalogue as a basis, and publish lists of such of their own books as are not to be found in it. By this means the expense and labour of cataloguing would be very greatly reduced, and the combination of these lists with the Museum Catalogue, when this came to be printed for the third time, say about 1925, would at last provide the desideratum of a universal register of literature. Ambitious undertakings like these, however, depend upon the co-operation of many governments and many institutions. We can speak with more confidence of the efforts of the Museum to provide what is only second in importance to the catalogue itself—a classified index of its contents. With this object in view several copies of the catalogue are printed on one side only, that when completed they may be cut up, and the titles sorted according to subject, and re-arranged in classified lists. Thus by simply putting together all titles bearing the press mark E, we shall obtain a separate catalogue of the Civil War Tracts; and a similar proceeding as respects the titles marked F, will afford a similar catalogue of the Croker collection of pamphlets on the French Revolution. Classed indexes to the literature of any subject can be made with equal facility, and as several copies of the catalogue will be available for treatment in the manner suggested, they may be varied for different objects, or to suit different systems of classification. For all strictly Museum purposes it would suffice to paste the titles excerpted on sheets of paper, but any of the indexes thus prepared might be printed and published. The only difficulty or delay would arise from the incorporation of the supplementary titles, which, as already explained, will have been continually added during the printing of the catalogue, and even this could be obviated by reprinting the entire catalogue as suggested above.