Overview
When James Cook and Charles Green observed Venus passing across the face of the Sun, they needed to be able to record the exact times when the planet ‘contacted’ the Sun’s edges. An accurate clock was essential.
By the middle of the eighteenth century, the best European clockmakers could make clocks that were precise enough for most astronomical work.
The clock that Cook and Green used is preserved in the Royal Observatory at Greenwich. This clock is believed to have belonged to Cook, and may have travelled with him. It is an example of the work of one of the best English clockmakers of the time.