Obviously, yes– editions of books matter. But why? Is there really a big difference between a book published in 1867 and an edition published the following year?
In the case of Edward Augustus Samuels, the difference is astonishing. But my astonishment is probably solitary, since his Ornithology and Oölogy of New England (1867) is a part of my research. I want to argue that the difference in the 1867 and 1868 editions of Ornithology and Oölogy of New England is significant because of the illustrations. A part of my research is a comparison of bird illustrations in 19th-century United States, so finding those primary illustrations is paramount to finding success. With Samuels, illustrations (in the form of engravings) exist in-text, as well as sometimes-colorized plates, inserted at various points. These color plates are, for me, why the edition matters.
My first exposure to Samuels was through Google books, where various editions of the work exist (1867, 1868, 1870). And the plates are all different. I did what historians are taught to do: go to a physical source. In this case, the only physical source was in a special collections/archive, cataloged as the 1867 edition. I was thrilled, since I could finally do some work. So, I cataloged the plates of the book, and went on with comparing them against other illustrations. In order to check on my work when the library had closed, I went back to Google books, only to find that the plates were all different from what I had cataloged. The library had mis-cataloged the book as an 1867 edition, when it was from 1868. My work was all done with the wrong edition! To make matters worse, different copies of the 1868 edition have different plates. The edition I looked at had golden-crested wrens on the plate facing the title page, while Google’s 1868 edition has the American bittern. Perhaps the same plates are just in different places, but that’s enough frustration in itself.
Maybe this is more of a problem for illustration research than it is for text-based research. Illustrations were (and are) a financial burden for printers and publishers, who hope for good returns on their investments. Plates could easily be removed or, as seen in Samuels, changed, just for a different edition. Regardless, getting to the earliest source is a summit for historians, and good librarianship, good searching, and digital repositories are essential in the journey.