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The history of astronomy can be used as much more than a diversion in teaching the principles of astronomy. In this talk I will focus on several historical aspects of time and calendrics that teach both science and history, and in the process cause students to realize that things have not always been (nor are they likely to remain) as they now are in the late-20th century. Examples include: (1) records of ancient solar eclipses that, despite their crude nature, precisely indicate the long-term slowing of the earth's rotation (why do they have those puzzling "leap seconds" one often hears about on New Year's Eve?), (2) problems of constructing a solar or (especially) a lunisolar calendar and various solutions (why did the date 7 October 1582 never occur? Why did the Soviet Union celebrate the "Glorious October Revolution" in November?), (3) the 18th-19th century dilemmas surrounding sundial ("true") time, mean time, and standard time as clocks became more accurate and transportation faster (Which is the "correct" time, anyway?), and (4) the 18th c. quest to "discover the longitude", eventually fulfilled by a chronometer that was seaworthy and accurate for months (how can you and a distant friend easily determine your difference in longitude?).
