There is a long account of this work in Dict. Historique, par Marchand: à la Haye, 1758, fo. sub. nom., Allais, as the author, observing—
"Il y a diversité d'opinions touchant la langue en laquelle il a été écrit ou composé."
The earliest he mentions is the English one of 1675, and an edition in the French, "à Paris, 1677;" which states on the title, Traduit de l'Anglois, whereas the second part is "imprimée à Paris chez l'Auteur, 1678," from which Marchand concludes that Allais was the writer, adding,—
"On n'a peut-être jamais vu de Fiction composée avec plus d'art et plus d'industrie, et il faut avouer qu'il y en a peu où le vraisemblable soit aussi ingénieusement et aussi adroitement conservé."
Wm. Taylor, of Norwich, writes to Southey, asking,—
"Can you tell me who wrote the History of the Sevarambians? The book is to me curious. Wieland steals from it so often, that it must have been a favourite in his library; if I had to impute the book by guess, I would fix on Maurice Ashby, the translator of Xenophon's Cyropædia, as the author."
to which Southey replies,—
"Of the Sevarambians I know nothing!" (See Gent. Mag. N.S. xxi. p. 355.)
Sir W. Scott, in his Memoirs of Swift, p. 304. (edit. 1834), speaking of Gulliver's Travels, says—
"A third volume was published by an unblushing forger, as early as 1727, without printer's name, a great part of which is unacknowledged plunder from a work entitled Hist. des Sévarambes, ascribed to Mons. Alletz, suppressed in France and other Catholic kingdoms on account of its deistical opinions."