comprehensive knowledge of a subject are generally not able to present it in the desired way. Co-operation is therefore necessary, and it is not always properly or thoroughly carried out, even where the necessity for it is realized. Proper co-operation between the expert and the popularizer involves (1) the selection and statement of the facts by the former; (2) their restatement and arrangement of the latter; and (3) the revision of this arrangement by the former. It is this third process that is often omitted even in serious cyclopedic work, and the result is inaccuracy. Often, however, there is no cooperation at all; the writer picks up his facts from what he considers reliable sources, puts them into eminently readable shape, dwelling on what seem to him striking features, heightening contrasts here and slurring over distinctions or transitions there. This process produces what scientific men call contemptuously “newspaper science,” and we have as well newspaper history, newspaper sociology and so on. They fill the pages not only of our daily press, but of our monthly magazines and of too many of the books that stand on our library shelves. It is unfair to blame the newspapers alone for their existence; in fact, some of the best simple presentations of valuable information that we have appear in the daily press. Then there are the text books. Any librarian who has ever tried to select a few of the best of one kind--say elementary arithmetics--to place on his shelves, knows that their name is legion and that differences between them are largely confined to compilers’ names and publishers’ imprints. In part they are subject to the same sources of error as the popularized works and in addition to the temptation to hasty, scamped or stolen work due to some publisher’s or teacher’s cupidity. This catalog might be extended indefinitely, but even now we begin to see the possibilities of rejection on the ground of falsity and inaccuracy. I believe that the chief menace to the usefulness of the public libraries lies, not as some believe in the reading of frankly fictitious narrative, but in the use of false or misleading history, biography, science and art. Not the crude or inartistic printing of toy money, but the counterfeiting of real money, is a menace to the circulating medium.