• Drug discovery isn’t all it’s cracked up to be. Dr Z isn’t the only person to have invented mephedrone (9 August, p 26). It was discovered in 1929, and a chemist known as “Kinetic” independently rediscovered it in recent years. Dr Z was the first to work out how to scale up production.
• Something didn’t add up in our review of Dave Goldberg’s The Universe in the Rearview Mirror (27 July 2013, p 50). A quote attributed to David Hilbert was actually spoken by Hermann Weyl.
