Thread's too long to read, so apologies if this has been posted.
I found a library sale copy of a Groff Conklin anthology, The Golden Age of Science Fiction. (This was a revised edition of The Best of Science Fiction, which was published in 1946.)
In it is a story by Arthur Leo Zagat, copyright 1936, originally published in Thrilling Wonder Stories. (A Gernsback magazine I believe.)
The title was The Lanson Screen. The title character invents a force shield that completely in effect puts everything within the shield into another universe. The shield is completely impenetrable. Lanson must turn off the shield from inside. A general orders the shield tested, on Manhattan. Lanson is killed in an accident, leaving Manhattan under a dome. (Ellipsoid, to be precise.) After sixty years, another genius finally figures out a way to dissolve the field. The final part of the story is a reading of part of the diary from one Manhattanite, all of whom died, followed by listeners continuing their planning for the future.
It is amazing how few SF writers come up with a truly original idea.