for a correct present view, or a complete history of the development
of any science, the technical reviews and society transactions must be
consulted. These will be the principal part of a scientific library,
and should be in the large public and college libraries in order to
cover advanced study.

They have, on the other hand, little place in small libraries--they
would seldom be of use, and are very expensive.

"But the popular periodicals every library needs. In the better class
of these reviews it is possible, if we know where to look, to find
several articles on both sides of almost any subject. Furthermore,
these are often written by the foremost authors or scientists, and are
in a language intelligible to all. The amateur cannot give the time or
patience to wade two-volume deep in the subject his club wishes him to
treat in half an hour's speech. The magazine gives just what he wants
in several pages. There are periodicals exclusively devoted to every
branch of every science, and magazines which, in their files, include
articles on all subjects. This mine of information has been opened up
by Poole's index. Since 1881, when the third and enlarged edition
of Poole's index was published, all this is common property for the
asking. Grouped around Poole and keeping pace with the times are the
Poole supplements, which ought, perhaps, to be named the Fletchers,
covering the five-year periods since 1881, ending respectively 1886,
1891, 1896. Then the Annual literary index gives a yearly index
of subjects and authors, and serves as a supplement to the Poole
supplement. For such as cannot be even a year without a periodical
index we now have the admirable Cumulative index, bi-monthly, edited
by the Cleveland public library. Thus all the principal periodicals
since the beginning of the century may be consulted by reference to