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Why did rescuing a 17th-century warship threaten to damage it?

Raising the ship Vasa in 1961 brought its waterlogged wood into an environment where drying could cause damage. Conservators had to support weakened wood during treatment and drying, and recovery was only one stage of the ship's preservation.

8–10 min

Questions you could explore

  • Why could apparently intact wet wood be vulnerable when it dried?
  • How does material treatment differ from supporting the ship's structure?

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History

Calibrating the radiocarbon clock

Carbon-14 decays at a steady, predictable rate, which makes it look like a simple stopwatch for dating ancient wood, bone, or charcoal. However, the amount of radiocarbon in Earth's atmosphere has varied over the millennia, so an accurate date relies on calibrating the measurement against tree rings and other materials whose calendar age is already known.

4–5 min

Calibrating the radiocarbon clock

History4–5 minCarbon-14 decays at a steady, predictable rate, which makes it look like a simple stopwatch for dating ancient wood, bone, or charcoal. However, the amount of radiocarbon in Earth's atmosphere has varied over the millennia, so an accurate date relies on calibrating the measurement against tree rings and other materials whose calendar age is already known.

History

How do archaeologists work out what happened first?

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.

4–6 min

How do archaeologists work out what happened first?

History4–6 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.

5–7 min

When Britain’s railways needed a shared clock

History5–7 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.

Why did rescuing a 17th-century warship threaten to damage it? | Speech Topic | speaking.app