In the case of Patrick O'Brian's books, to pick an author and to move closer to the point of this page, we have examples of many kinds of first editions.  Take the Aubrey-Maturin Series.  We are fortunate to have Arthur Cunningham's bibliography for Patrick O'Brian, in Patrick O'Brian: Critical Essays and a Bibliography

The title page might be called the Author's page and provides the name of the book, the author/editor, and publisher.

So.  Is this book a first edition?

We do find in the bottom block more about the printing of this book and a point we can later compare with Blue in the Mizzen, we sometimes find a row of numbers indicating the particular printing of this book.  The mailing address of the publisher, of course, but on the bottom row we see a string of digits, one to zero.  This tells us the printing which, in this case, was the first.  When it's printed again, the first digit is removed and the string will start with "2," indicating the second printing.  How many books were printed in the first printing?  This data, plus a knowledge of supply and demand will give you an idea of the worth of your first edition.  If the first printing, and thus the "first edition" were 10,000 and the second printing was 100,000, you can see the enhanced value of the first edition.

That brings us to Blue at the Mizzen.

O'Brian was a very commercial writer, of necessity.  From 1945, which begins his second identity, he lived in penury and enjoyed telling stories about being forced to use the backs of galley pages as writing material to save money.  He moved to France's south-eastern coast, near the Spanish border, as another economy move and lived for several years in "reduced circumstances."  Things got a bit more comfortable when the A-M series began providing a small but steady income.  He received several other commission to write but eventually, the series became his sole output. 

In 1991, W. W. Norton began publishing the Aubrey-Maturin series in the US, where it had begun publication by Lippincott in 1969.  (This is the first edition of the series.) When Norton started publishing Patrick O'Brian,  Norton also began a very shrewd policy of re-printing all the earlier novels.  Norton first published Nutmeg of Consolation (14) in 1991 after it had appeared earlier in the UK and subsequently tried to publish each new novel simultaneously in the US and UK.

List from a Norton novel.

This simultaneous publication suggests that the page images ( The results of typesetting in the UK. ) of each novel were transmitted to the US and used for publication.  What then of the title change for Clarissa Oakes to The Truelove?  Any clues offered there?  It further suggests that the paperbacks used reduced page images.  If anyone can produce a typo that appears on both the hard and soft cover, we could prove this point.

The Dustcover.

Norton's initial publication of each A-M novel in hardback had the "wraparound" cover format shown above for Blue at the Mizzen.  Later Norton published hardbacks with a dustcover having a  common spine that also had the volume number at its bottom.  This spine's color is the same for all twenty novels and this permits one to have a complete set with the same spines.  All future hardbacks will have this dustcover.  This permitted Norton to publish and sell a complete set with a common appearance beginning after the novel 17.  (If you  find the need to count in order to establish the ordinality of a novel, knowing The Thirteen Gun Salute is the thirteenth novel helps.)  Though the wrap-around dustcover suggests an early edition, this edition  may have gone through several printings as indicated by the "printing line."

In 1999, Patrick O'Brian again visited the US.  His wife had died and O'Brian was in ill health.  The signing tour for this book was very limited and frequently was no signing at all but the availability of stacks of previously signed books.  Indeed, the tour was cut-off abruptly for health reasons.  Below is an image of the verso t.p. of Blue at the Mizzen.  Note that it proclaims itself a "First American Edition 1999" and that the "printing" line is missing.   The omission of the printing line is a first for the series though Norton books have had several errors.  With the appearance of Blue at the Mizzen was planned a special slipped cased limited, signed edition of 250 books but this special edition book was delivered very late which may have been due to O'Brian's ill health.  O'Brian apparently had signed single sheets which were "tipped" into completed books.  The printing line is absent from these books, too.  Subsequent editions contain the printing line beginning with "2."

However, using the definition that a first edition is the first bound edition to appear in public, the W. W. Norton Blue at the Mizzen is the first edition since the UK edition did not appear until several months after the US edition.  There has been no explanation as to why HarpersCollins missed the announcement date.