Prince Rupert's drops tail crack shatter compression

Glass drops resist blows but shatter from tail cracks

Prince Rupert's drops are glass beads made by putting molten glass into cold water. Rapid cooling leaves the surface tightly squeezed and the inside under tension. The bulb can withstand severe blows, but a crack entering from the thin tail can race through the drop and shatter it.

Dark peppered moths became common and then became rare again

During the Industrial Revolution, soot darkened trees around Manchester. Dark peppered moths became harder for predators to see and grew very common. After air pollution fell and trees became lighter again, dark moths became rare.

Norovirus can infect someone with an extraordinarily small dose

Norovirus spreads easily through contaminated food, water, surfaces and close contact. Experiments and outbreak investigations suggest that very small numbers of infectious particles can sometimes establish an infection. That helps explain why the virus spreads rapidly in places such as cruise ships, schools and care homes.

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Prince Rupert's drops tail crack shatter compression

Glass drops resist blows but shatter from tail cracks

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