• William Kirby’s letter about siting nuclear plants by the sea should have referred to our being committed in 20 years’ time to the risk of catastrophic sea level rises in a century or more (28 November).
• Watt’s that? The energy used by a Google web search is 0.3 watt-hours or 1000 joules (7 November, p 44)
• It was in 1844 that historians proposed that the Black Death was a flea-borne bacterial disease; and the correspondence suggesting its use in the siege of Heraklion ended in 1651 (28 November, p 15).
