Determine the edition of the book and the year of publication, both of which are found on the copyright and dedication page that is located in the front of the book. The edition is indicated by a string of numbers or letters--i.e., 1,2,3,4,5,6,7,8,9--or letters--a,b,c,d,e,f,g--displayed in a forward or backward sequence, depending upon the publisher. If the numbers 1 through 9 or letters a through g appear in any sequence, you have a first edition. If the numbers 2 through 9, or letters b through h are shown, you have a second edition and so on.
Confirm the authenticity of the book's edition and year of publication by researching the author's bibliography via an online search engine tool, such as WorldCat at worldcat.org, to find and search hundreds of U.S. libraries for a detailed analysis of every edition of every title published by the author. You can also find this resource in the reference center or subject catalog of your local library.
Double check your facts by searching the National Union Catalog of Manuscripts of the Library of Congress (see Resources) for a combined card catalog of hundreds of U.S. libraries.
Contact the Special Collections Department at the Smithsonian Library (see Resources), which does not appraise old books but may be able to provide information as to the significance of antiquarian books in such fields as history of science and technology, natural history, selected aspects of American history and the history of decorative arts.
Consult a professional book appraiser to determine the age and value of the book you have for the experience and specialized knowledge needed to distinguish the books age. The Smithsonian Institute Libraries offers a list of reputable book appraisers on their website (see Resources), or you can use a search engine to locate one yourself.