There is one incidental circumstance connected with the Museum press-arrangement of such importance that I may hope to be allowed a few words respecting it, although I adverted to it in the course of the discussion yesterday. I allude to the fourth copy of the catalogue. It is generally known that the titles of books catalogued at the Museum are transcribed trebly on carbonic tissue-paper by a manifold writer, and that the catalogue is thus kept up in triplicate. But I suspect it was not generally known until the delivery of the President's address that a fourth copy is taken at the same time. These fourth slips are kept in boxes, and then arranged, _not_ in alphabetical order as in the catalogue, but according to the position of the books upon the shelves. Now, as each shelf is restricted to a single subject, it follows that an arrangement by shelves is tantamount to an arrangement by subjects—that is, a classed catalogue. A great deal, of course, remains to be done both in the way of subdivision and of incorporation; it is nevertheless the fact that—thanks to the foresight of Sir Anthony Panizzi and Mr. Winter Jones—the foundation of a classed Index to Universal Literature has been laid by simply putting away titles as fast as transcribed, without the nation having hitherto incurred any cost beyond that of the pasteboard boxes. The apparently gigantic task being thus far simplified, I earnestly trust that public aid may be forthcoming for its completion, ere the accumulation of titles shall have rendered it too arduous. Fully sympathising with our friend Mr. Axon's wish to see the Museum Catalogue in print, I am yet averse to attempting to print it just as it stands: in the first place, because I regard the undertaking as beyond our strength; and in the second place, because, although such a catalogue would tell the student at a distance what books by particular _authors_ were in the library, it would not tell him what books on particular _subjects_ existed there; the latter, as it appears to me, being the more urgent necessity of the two. I should therefore be inclined to recommend the preparation of an abridged classified index, compiled from the fourth-copy slips I have been describing, and its publication from time to time in sections severally complete in themselves, as affording the best means for a gradual solution of the problem. Most of these sections, I have little doubt, would by their sale nearly repay the expense of publication, which a complete alphabetical catalogue of the library certainly would not. These remarks, it will be perceived, coincide with those made yesterday by Mr. Vickers, which struck me as eminently sensible and practical.