The books are described as folio, quarto, octavo, duodecimo, etc., according to the apparent size of the volume, and not according to the printer's designations derived from the fold of the sheets.

In the alphabetical arrangement, the prefix Mc, M', or Mac, is treated uniformly as a component part of the word, as if spelled Mac. Thus, McLeod or M'Leod precedes Maclure. In like manner, the prefixes New, La, Du, etc., are treated as component parts of the words to which they belong. Thus, New England follows Newell instead of preceding it, as it would do if the prefix New were treated as a separate word.

It is one of the aims of the present catalogue to furnish with the titles a sufficiently full collation of each work. Thus it is made a part of the description to give the number of pages in the case of all works not exceeding two volumes, together with the number of maps and plates, if any, and the name of the publisher. The information thus conveyed will, it is believed, be found of practical value to readers, as conveying at a glance some idea of the extent of each work, while the addition of publishers' names is useful as supplying a guide to the identification of editions. In the case of books printed without date, the actual or approximate date is uniformly supplied, in brackets.

Brackets in any part of a title indicate that the words included in them are not found in the title, but are inserted.

The letter s, affixed to any title, denotes that the work belongs to the library of the Smithsonian Institution, now deposited with the Library of Congress.