essays or dissertations of an independent kind on subjects relating to the Tartars,—­one of these occupying 106 pages, and entitled Versuch zur Geschichte der Kalmuekenflucht von der Wolga ("Essay on the History of the Flight of the Kalmucks from the Volga").  A French translation of the Letters, with this particular Essay included, appeared in 1825 under the title Voyage de Benjamin Bergmann chez les Kalmueks:  Traduit de l’Allemand par M. Moris, Membre de la Societe Asiatique.  Both works are now very scarce; but having seen copies of both (the only copies, I think, in Edinburgh, and possibly the very copies which De Quincey used), I have no doubt left that it was Bergmann’s Essay of 1804 that supplied De Quincey with the facts, names, and hints he needed for filling up that outline-sketch of the history of the Tartar Transmigration of 1771 which was already accessible for him in the Narrative of the Chinese Emperor, Kien Long, and in other Chinese State Papers, as these had been published in translation, in 1776, by the French Jesuit missionaries.  At the same time, no doubt is left that he passed the composite material freely and boldly through his own imagination, on the principle that here was a theme of such unusual literary capabilities that it was a pity it should be left in the pages of ordinary historiographic summary or record, inasmuch as it would be most effectively treated, even for the purpose of real history, if thrown into the form of an epic or romance.  Accordingly he takes liberties with his authorities, deviating from them now and then, and even once or twice introducing incidents not reconcilable with either of them, if not irreconcilable also with historical and geographical possibility.  Hence one may doubt sometimes whether what one is reading is to be regarded as history or as invention.  On this point I can but repeat words I have already used:  as it is, we are bound to be thankful.  In quest of a literary theme, De Quincey was arrested somehow by that extraordinary transmigration of a Kalmuck horde across the face of Asia in 1771, which had also struck Gibbon; he inserted his hands into the vague chaos of Asiatic inconceivability enshrouding the transaction; and he tore out the connected and tolerably conceivable story which we now read.  There is no such vivid version of any such historical episode in all Gibbon, and possibly nothing truer essentially, after all, to the substance of the facts as they actually happened.”

Professor Masson’s Appended Editorial Note on the Chinese Accounts of the Migration (Vol.  VII, pp. 422-6): 

“As has been mentioned in the Preface, these appeared, in translated form, in 1776, in Vol.  I of the great collection of Memoires concernant les Chinois, published at Paris by the enterprise of the French Jesuit missionaries at Pekin.  The most important of them, under the title Monument de la Transmigration des Tourgouths des Bords de la Mer Caspienne dans l’Empire de la Chine,