End letter - אגרת המיוחס הר"י אייבשיץ על האגדות

From here:

I now see that the episode in question and this letter is already mentioned in the Shefer translation of Graetz, in Zinz's Gedulot Yehonoson V. 2 pgs. 135ff, 214 and in YY Greenwald R Yonoson Eibschutz pg. 57 ff (the last two books can be found at hebrewbooks.org, Zinz especially has a lot of good material on R' Yonason Eibschutz.)

[Update:Prof. Shnayer Leiman was kind enough inform me of his article in Or Ha-Mizrach 29(1981), pp. 418-428 containing the short commentary to Aggadot mentioned in the above letter.

(He also informed me that: "After I published that essay, the Perush Li-Kzat Aggadot appeared in print several times. You will find it easily in a large volume that gathers together color reproductions of the sha'ar blatt of the major editions of shas through the ages.")

The following excerpt:

complements Eliezer's point in his recent Seforim blog post:

"Besides for these two Gedolim opposing Copernicus, R. Yonsan Eybshutz who was also knowledgeable in Astronomy was also opposed as he writes in 1779:

ועבור זה נתטפשו הרבה מתוכנ' קופרניקוס וסעייתו באמרם שהארץ מסבב אבל שקר נחלו והאמת עד לעצמו כי הארץ לעולם עומדת... (יערות דבש, חלק א, דרוש ד, דף לו ע"א).

(Neher, idem, p. 253, is incorrect when he writes that Eybshutz was positive towards Copernicus' theory). "

See also here on the well known explanation of R' Yonoson Eibschutz that the Tower of Bavel was actually some sort of proto-rocketship. I'm not certain which books he refers to -וכבר חברו בזה חיבורים איך לעשות ספינה כזה לילך לכדור הירחי

(although a Google search might be useful here)

but his rocket sounds a bit like the one in Jules Verne - "From the Earth to the Moon" (written decades after RYE's passing).