When Kevin O Malley’s home-built time machine becomes operable, he uses it to research his Irish ancestors during the potato blight of 1845.
The past is changeable but self-correcting. Easy to change small things; harder to change big ones.

Variants

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  1. “Slan Libh” by Michael F. Flynn, in Analog, November 1984.
  2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . written by Michael F. Flynn