Such a collection must include also the general mass of books sought and held by local libraries--the books for the ordinary reader; the daily tools of research. Its maintenance will involve processes--of classification and cataloging--highly costly. Suppose the results of these processes could be made generally available, so as to save duplication of such expenditure upon identical material held by local libraries? A collection universal in scope will afford opportunity for bibliographic work not equalled elsewhere. Such work centered there might advance the general interest with the least aggregate effort. The adequate interpretation of such a collection will involve the maintenance of a corps of specialists. Suppose these specialists could be available to answer inquiries from all parts of the country as to what material exists on any particular subject, where it is, how it may be had, how most effectively it may be used? There are special collections already existent in various localities in the United States and likely to come into being through special local advantage or incentive, or the interest of private collectors, or private endowment--which cannot be duplicated at Washington. Suppose there could be at Washington a bibliographic statement of that which is peculiar to each of these collections; in brief, a catalog of the books in the United States--not of every library, not of every copy of every book, but of every _book_ available for an investigator? There are various bibliographic undertakings which may be co-operative. Suppose there could be at Washington a central bureau--with approved methods, standard forms, adequate editorial capacity, and liberal facilities for publication--which could organize and co-ordinate this work among the libraries of the United States and represent them in such of it as--like the new Royal Society index--is to be international? There is the exchange of material duplicated in one library, needed by another. Suppose there could be at Washington a bureau which would serve as a clearing house for miscellaneous duplicates as the Bureau of Documents serves for documents? It might accomplish much without handling a single article; it might, like a clearing house proper as it were, set debit against credit, _i. e._, compare the deficiencies in one library with the surplus in another and communicate the results to the institutions interested. It might do this upon slip lists sent in by each--of duplicates and of particular deficiencies--in sets, for instance. One of my associates has been guilty of this very suggestion. It is likely to bring something upon his head. He may have his choice between live coals and the ashes of repentance.