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How did refrigerators change the business of selling ice?

Before household refrigeration, cooling a New York kitchen could mean harvesting river ice, storing it, moving it by barge and delivering it by wagon. Mechanical cooling changed where that work could happen. The Hudson River’s ice trade makes the change concrete without requiring a story about one enormous monopoly.

5–7 min

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Why does a radiocarbon date need a second kind of clock?

History4–5 minA radiocarbon measurement does not translate directly into one calendar year. The amount of radiocarbon in the atmosphere has varied, so dating relies on comparison with material whose age is already known.

History

Reading a buried timeline

A deep object is not necessarily the oldest thing at an archaeological site. A later pit can cut through earlier ground, leaving a sequence that has to be reconstructed from relationships between layers.

12–15 min

Reading a buried timeline

History12–15 minA deep object is not necessarily the oldest thing at an archaeological site. A later pit can cut through earlier ground, leaving a sequence that has to be reconstructed from relationships between layers.

History

When Britain’s railways needed a shared clock

A timetable becomes awkward when the clocks at its two ends disagree. In nineteenth-century Britain, railway journeys helped turn local time into a shared coordination problem, while the telegraph helped distribute an answer.

8–10 min

When Britain’s railways needed a shared clock

History8–10 minA timetable becomes awkward when the clocks at its two ends disagree. In nineteenth-century Britain, railway journeys helped turn local time into a shared coordination problem, while the telegraph helped distribute an answer.

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