[Illustration:  Title card. (Reduced; actual size, 7-1/2 x 12-1/2 cm.)

973.2   Old times in the colonies
C65   Coffin, C.C.]

As the use of the library for reference work increases, the question will often be asked, has it any books on a certain subject?  Add, therefore, to your author- and title-list a subject-list.  Make this by writing a card for each book with the subject of which it treats the first word upon it.  Arrange this also in the same alphabetical series with the other two.  In some cases the book’s title and its subject will be identical; for example, Geology, by Tompkins, or Washington’s boyhood, by Jones.  For such books one card answers for title and subject.  For fiction no subject-card is necessary.  On the other hand, many books have to do with more than one subject; a volume of essays, for example, or a group of biographical sketches.  For such it is desirable to add to the subject-list by writing as many cards for each book as the importance of the several subjects therein and the space the author gives to them seem to demand.  Each card will have for the first word of its entry the subject to which it refers, followed by the author and title of the book.

Arrange these cards also alphabetically with all the others.  Put on every card in the catalog the call-number of the book to which it refers.  This author-title-subject-list, or dictionary catalog, will tell at a glance if the library has books a) by a certain author; b) with a given title; c) on a given subject.  These are the questions most often asked.

[Illustration:  Subject card. (Reduced; actual size, 7-1/2 x 12-1/2 cm.)

973.2 U.S. history- colonial. 
C65 Coffin, Charles Carleton 1823-
        Old times in the colonies.
        460 p. il.  O N.Y. c[1880]]

There are in print several books giving rules for cataloging.  Some of these are mentioned in the chapter on Things needed (9).  In a small library which is always to be small it is not necessary to follow all the rules laid down in these books.  It is much better, however, to do all the work, even in a very small library, according to the most approved methods.  So to do brings you in touch with your fellows and gives you the comfort which comes from the consciousness of work well done, even if the amount of the work be small.

In writing the subject-headings difficulties will soon arise unless you follow certain general rules and are careful also to be consistent in your work.  For instance, at intervals during a few months you add to the library books on horses, cows, sheep, goats, camels, and pigs; some dealing with one animal, some with two or more.  If for the first one you write a subject-card with the catch-word or entry-word at the top “Domestic animals,” and for the next one “Farm animals,” and for the next one “Animals, domestic,” you will scatter the references to domesticated animals all through your catalog, to the despair of those who would use it.  You can guard against this, and easily, if your catalog is small, by looking to see what you have already written every time you write a new subject-entry-word, and by following out a previously devised plan in the making of your entries.  The safest way is to get a printed list of headings and catalog rules and follow them. (See chapter on Things needed, 9.)