What does oblong quarto mean?

Answer 1

Since the sixteenth century, books were printed in a variety of "formats," referring to the relationship between an individual leaf of a book and the original size of the printed paper. (See, for example, Print Culture and Music in Sixteenth Century Venice, p. 36). The quarto format is attained by taking the printed sheet and folding it twice (in quarters) to produce four leaves. An oblong format, as opposed to upright,simply has a longer horizontal axis than a vertical one, what we would call "landscape" mode. This is often used for art books and "coffee table" books.