The Annual Tyndall lecture, Seeing is believing?, will be presented by Dr Zbig Sobiesierski on Thursday at 2.30 p.m. in the RDS Concert Hall, Ballsbridge, Dublin. The lecture is organised by the Institute of Physics in Ireland and the RDS. It is open to all members of the public, but large groups are requested to book in advance. Admission is £1. There will be a limited number of tickets at the door. For booking contact the RDS on (01) 2407222.