When Kelly Weill begins her capsule history of the modern flat-earth movement in the opening chapters of her recent book Off the Edge (Weill 2022; reviewed in Branch 2022), she credits Samuel Birley Rowbotham (1816–1884), who wrote under the pseudonym “Parallax,” as its prime mover. In doing so, she agrees with the general scholarly consensus: for example, Christine Garwood’s definitive history Flat Earth credits Rowbotham as responsible for the “modern public revival of the flat-earth idea” (Garwood 2007, 36). But following the late Robert J. Schadewald, Weill also hints at a precursor: “an anonymous author had self-published a short booklet called The Anti-Newtonian in 1819 … its specific arguments are so similar to Rowbotham’s that he really appears to have taken large parts for his own purposes” (Weill 2022, 18–19, citing Schadewald 2015, ch. 1). Who was the anonymous author of the booklet? Were its arguments similar to Rowbotham’s? And did it indeed influence him? The Flat Earth according to The Anti-Newtonian According to The Anti-Newtonian, as Schadewald reports, “the earth is a vast circular …