From Sundials to Atomic Clocks

TL;DR — NIST’s popular history of timekeeping, from sundials to atomic clocks (Monograph 155, 1999 edition).

How much weight it carries: A well-made public-education book from a federal standards agency.

Where this came from

• Will Manidis’s “most underrated PDF” thread, July 2023 — routing record: The Most Underrated PDF on the Internet (July 2023)

320 pages. A copy is archived locally against link rot; the header links the original source.