Philosophiae Naturalis Principia Mathematica

No book-club apparatus applies. The practical confusions are the later Latin editions of 1713 and 1726 offered as a 'Principia first edition' on the strength of the title alone, the 1729 Motte translation described as a 'first edition' without the qualifier 'in English', and modern facsimiles and reissues. The Pepys imprimatur on the title and the two 1687 imprint forms — not the date on the title alone — are what settle a copy.