4 ideas
In Mitchell's 1881 story, the narrator and his cousin Harry inherit a stopped antique Dutch clock from their Aunt Gertrude. A mysterious Dutch professor winds it so its hands run backward, and it carries the three of them to the 1574 Spanish siege of Leiden.
The story makes the instrument that measures time the instrument that controls it. This made it one of the earliest fictional time-travel devices, predating H.G. Wells's time machine by fourteen years.
The travelers do not alter history; their presence in 1574 was already part of it. The past they visit depends on their visit, so cause and effect form a self-consistent circle rather than a branching or rewritten timeline. This is an early fictional form of the causal loop, or bootstrap paradox.
The story sets its impossible mechanism inside a documented event: the 1574 siege of Leiden, which ended when the Dutch breached their dikes so relief ships could reach the city. Grounding the fantasy in a verifiable historical crisis lends the time journey stakes and plausibility that invented settings lack. The historical record constrains what the travelers can do and gives the loop its meaning.