698 THE AMERICAN JOURNAL OF SOCIOLOGY
or twice to ask the reader " unfamiliar with higher algebra " to accept mathematical formulas on faith. The topics to which most attention is given are the choice of units of measurement; the measurement of individuals, of groups, of differences, of changes, and of relationships ; and the reliability of measurements and sources of error. Strong emphasis is laid upon tables of frequency. In statistical work involving the element of time this device is relatively less useful, and other methods of presentation not discussed by Professor Thorndike are more important. One good feature of the book is the scrupulous care taken to give all the data used in the illustrative examples, diagrams, and problems. The last chapter contains references for further study, and the appendix a multiplica- tion table up to 100 X loo, a table of square roots up to 1,000, and a collection of miscellaneous problems for additional practice. In reading the book two troublesome errors of the press were noticed. On p. 57, Figs. 52 and 53 are wrongly numbered, unless the refer- ence on the next page is misprinted, and on p. 79 the reference to p. 79 ought to read p. 74.
WESLEY C. MITCHELL.
THE UNIVERSITY OF CALIFORNIA.
Library of Congress: A. L. A. Catalog. 8000 Volumes for a
Popular Library, with Notes, 1904. Prepared by the New
York State Library and the Library of Congress, under the
auspices of the American Library Association Publishing
Board. Editor : MELVIL DEWEY, Director New York State
Library and Library School; Associate Editors: MAY
SEYMOUR, Education Librarian, New York State Library;
MRS. H. L. ELMENDORF, Special Bibliographer, Buffalo
Public Library. Part I, " Classed ; " Part II, " Dictionary."
Washington: Government Printing Office, October, 1904.
The A. L. A. Catalog is perhaps the most important book of the
year in point of real social influence. Appearing as it does with the
stamp of approval of the American Library Association, awarded
high honor at the Louisiana Purchase Exposition, and made doubly
valuable through the co-operation of the Library of Congress, which
not only prints and liberally distributes the work, but has prepared
printed catalogue cards for the entire collection, this Catalog must of
necessity be the guide of the majority of American libraries, both
