One of the few translations made by Michel Foucault, and perhaps the most unusual, was an essay by literary theorist Leo Spitzer.
It was published as “Arts du langage et linguistique”, in Leo Spitzer, Etudes de style, Paris: Gallimard, 1970, pp. 45-78. (There are several other pieces in there, translated by others. The text has since been reissued in the Tel series.) Daniel Defert’s ‘Chronology’ dates the publication to 21 January 1970.
The original text was “Linguistics and Literary History”, in Leo Spitzer, Linguistics and Literary History: Essays in Stylistics, Princeton: Princeton University Press, 1948, pp. 1-39.
The original was written in English, even though Spitzer had written most of his earlier work in German. All of the other translations by Foucault were from German to French, so this is unusual in being from English to French.
The other issue which I think is interesting is the date of the translation. The 1970 date of the collection Etudes de style is well after Foucault had an international reputation. All of his other translation work dates from over a decade before – he edited the translation of Ludwig Binswanger, Le rêve et l’existence, which was published in 1954; co-translated Viktor von Weizsäcker, Le cycle de la structure for publication in 1958, and in 1959-60 translated Kant’s Anthropologie, which was submitted as his secondary thesis in 1961 and published in 1964. The Spitzer essay was the last translation with which he was involved.
It’s of course possible that Foucault did indeed translate the text for a 1970 edition, perhaps a year or two before. But it seems unlikely. One of the only essays I know on this text (Geertjan de Vugt, ‘Art du langage et linguistique: on Foucault’s Spitzer’) makes quite a bit of the date, and how unusual it was for Foucault to turn to this text after what he had written on linguistics in The Order of Things.
But several sources suggest that the date might have been earlier. In David Macey’s The Lives of Michel Foucault, pp. 120, 497 n. 2, the date of the Gallimard text is given as 1962. The same date is given in James Bernauer’s Michel Foucault’s Force of Flight, pp. 232-3 (and the bibliography of The Final Foucault, p. 121), and in Jacques Lagrange’s Complèment Bibliographique in Dits et écrits, vol IV, p. 829. There is of course the risk that bibliographies are copying each other, rather than independently checked, though this seems unlikely given the sources. Richard Lynch’s bibliographic tools also indicate that it is listed in Michael Clark’s Annotated Bibliography (ref B031), and Lynch lists the 1962 date (though here I am fairly sure that is a product of following his sources).
A 1962 date would make much more sense – it could have been done c. 1961 around the time of the thesis, or perhaps a little earlier. But I can find no indication, beyond the ones cited above, that this date is accurate. The Gallimard text is clearly dated as 1970, which is confirmed by Gallimard’s website, Worldcat and other library sources.
Where, then, did anybody get the 1962 date? The most plausible explanation I can think of is that a reedition of the American text was from that year. But unless the bibliographies are copying each other, this seems unlikely to be a slip more than one person could have made. Anybody shed any further light on this?
Update 7 December 2017: To clarify, the pagination in the two Gallimard editions is the same – both in the NRF/Bibliothèque des Idées and Tel versions, the essay is on pp. 45-78. The NRF edition is dated to 1970 – with 1er trimester 1970 as its copyright date – and the Tel edition to October 1980, with subsequent reprints. According to the Gallimard site, the NRF edition was printed 21 January 1970, and published 4 February 1970 (which would fit with Defert’s dates, noted above); the Tel edition was published 14 November 1980.
The book also appears in the bibliography of Clare O’Farrell’s Foucault: Historian or Philosopher? There it is dated to 1962, with a reprint in 1970 (p. 156). It also appears in Sheridan’s Michel Foucault: The Will to Truth, 1980, p. 228 as 1962.
In summary: indications of the 1962 date come from Sheridan, Macey, Bernauer, Lagrange, Clark (Lynch), O’Farrell; the 1970 date comes from Defert, de Vugt, Gallimard, Worldcat and the actual Spitzer booksI’ve seen.
Update 11 December 2017: The bibliographies of Power, Truth, Strategy, 1979, p. 94 and Power/Knowledge, 1980, p. 263 both give the 1962 date.
Two very generous endorsements for my next book 
Michel Foucault’s account of the subject has a double meaning: it relates to both being a “subject of” and being “subject to” political forces.
Originally published in 1942, at the height of the Second World War, Land and Sea: A World-Historical Meditation recounts Carl Schmitt’s view of world history “as a history of the battle of sea powers against land powers and of land powers against sea powers.” Schmitt here unfolds his view of world history from the Peloponnesian War to European colonial expansion to the birth pangs of capitalism, while polemically setting Nazi Germany as a continental land power against Britain and the United States as its maritime enemies. In Land and Sea, Schmitt offers his interpretations of the rise of Venice, piracy, “corsair capitalism,” the spatial revolution of European colonial expansion, the rise of the British empire, and his readings of thinkers as diverse as Seneca, Shakespeare, Herman Melville, and Benjamin Disraeli.
