Marginal annotations to printed books are a little studied aspect of the history of books and the transmission of ideas, providing a commentary on published texts which is conventionally anonymous, critical and economical. While many annotations are no more than individual comments on or disagreements with what an author has written, in a significant number of cases marginal notes have been found to be authorial, often adding an important new dimension to the original text.

Vols. for 1871-76, 1913-14 include an extra number, The Christmas bookseller, separately paged and not included in the consecutive numbering of the regular series.