This paper explores a trans-Atlantic clash about time: in 1899, American philosopher Mary Calkins argued we should not spatialize time; in 1899, British philosopher Victoria Welby argued we should. I take their disagreement as a starting point to contextualize, study, and compare the accounts of time presented in their respective articles. Both Calkins and Welby cared deeply about time, writing on the topic across their careers, but their views have not been studied by historians of philosophy. This is unfortunate, for (...) I argue their novel theories reward attention. Calkins’ 1899 account draws on Kant to arrive at the earliest American-British causal theory of time, pioneers the metaphysical applications of temporal experimental psychology, and replies to F. H. Bradley’s proclamation that it is ‘impossible’ to explain the appearance of time. Meanwhile, I read Welby’s 1907 account as offering a radical metaphysic, on which time is literally a kind of space, resonating with 1880s literature around the ‘fourth dimension’ and H. G. Wells’ 1895 novel The Time Machine. I have uncovered an early draft of Welby’s paper dating to 1902 and, using this alongside other unstudied writings by Welby, trace the development of her views from the 1880s onwards. (shrink)