Mi enretigis la jenan novelon / I have digitized this story from International Science-Fiction, No. 2, June 1968:
“In 2112,” by J. U. Geisy & J. B. Smith, translated from Esperanto by Forrest J. Ackerman
Here is what Ackerman says at the end about its origin:
This antiquity, written in the year Tarzan was born in the pre-Gernsback prehistoric era of "different" stories and "offtrail" stories and "scientific romances," is from the early literature of Esperantujo (Homeland of Esperantists).I would like to track down the Esperanto version of the story, if possible. / Mi volas trovi la esperantan originalon de ĉi tiu traduko.