Today Powells.com posted a guest blog post I wrote for them about the Venus transit voyages of the 1760s and the technological (not just scientific) motivations behind them:

“Rare as it is, the Venus transit has an outsized impact on the world. The transit launched the legendary careers of Captain Cook and Mason and Dixon — surveyors who wouldn’t have staked out the definitive line between American North and South without first proving themselves on a Venus transit voyage. …

“The Venus transit also stands at the crossroads of perhaps the single greatest technological challenge in human history: practical navigation at sea.

“It on was this last point that I found a skewed account in recent popular histories — and ultimately tried to right the record a bit with my new book.”