arch bridge compression outward force abutments

An arch bridge pushes outward at its supports

A curved arch supports a bridge deck by carrying forces through the arch in compression. Those forces also push the arch outward, so strong abutments at either end are needed to keep it from spreading or collapsing. The deck can sit above, below, or through the arch.

Cape Verde has a diaspora larger than its population at home

Generations of emigration have created Cape Verdean communities across Europe, the Americas and Africa. Estimates of the diaspora vary depending on whether they count only people born in Cape Verde or also their descendants. By broad definitions, the number of people with Cape Verdean roots living abroad exceeds the country's resident population.

A nonexistent island marked a border

Old maps showed Isle Phelipeaux in Lake Superior as an apparent duplicate of Isle Royale. Explorers used it as a landmark for the boundary between the United States and the territory that would become Canada, but later surveys found no island there.

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arch bridge compression outward force abutments

An arch bridge pushes outward at its supports

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