• Green chemist Jim Hutchison is at the , not Oregon State University as we said (13 March, p 34).
• We said alkali-vapour lasers have “mass-to-power ratios that far exceed other lasers”; we meant “power-to-mass” (27 February, p 22).
• We referred to “Antonie Leeuwenhoek” as “father of the microscope” (27 February, p 36). His family name was van Leeuwenhoek; our dictionary calls him Antoni, though many other spellings are also in use.
