Joyce Chaplin

In​ 1789, a year famous for a number of other reasons, the Swiss scientist and alpinist Horace Bénédict de Saussure invented the cyanometer, an instrument that measures the blueness of the sky. This simple paper colour-wheel had 53 sections, ranging from white to deep blue. Saussure tested the cyanometer at different elevations in Switzerland, hypothesising that the sky gets...

The Eclair was a British steam sloop charged with policing the slave trade. In November 1844 she set out hopefully in a naval squadron for Sierra Leone, where she spent five months patrolling for slavers. West Africa was known to harbour ‘fevers’ to which Europeans had little resistance, but the officers and crew remained in good health, and the sailors were even granted shore...

The breadfruit is native to a number of Pacific islands, and is nowadays grown more widely in the tropics. It has never become a global commodity in the same way as other exotic foodstuffs – coffee, tea, sugar, bananas – even though it requires less labour than sugar or tobacco to grow, needs no more refrigeration than bananas for its transport and can be tinned or preserved.

Its...