The sf genre obtained its name and social identity during the early decades of the twentieth century in the American pulp magazines. But a recognizable literary tradition was, according to many critics, conceived during the industrial revolution and born during the latter half of the nineteenth century in Jules Verne’s voyages extraordinaires and H.G. Wells’s fin-de-siècle “scientific romances.” These two sf variants pioneered by Verne and Wells (hard/didactic versus speculative/fantastic) became the two major modes that have dominated the genre ever since.