From Nick Thomas
I was surprised that in the article on the Venus transit the pioneering work of Jeremiah Horrocks was not mentioned (5 June, p 32). His observations of a transit of Venus in 1639 are the first recorded, and I understand he was the first to realise that every 113 years there are two transits eight years apart, not just one. This is also missed in the interesting “Histories” article in the same issue (p 52).
In the 1969 edition of the Larousse Encyclopaedia of Astronomy “our” transit was predicted to be on 7 June instead of 8 June. That we are still getting it wrong underlines to my mind the achievement of the young Horrocks – an amateur who died at the age of 24, and who had no computers to help him.
Kings Langley, Hertfordshire, UK
