• We incorrectly stated that the Limehouse declaration, which signalled the birth of the SDP, was made "30 years ago today" in a leader on 22 March. It was in this week 30 years ago that the SDP was founded but the Limehouse declaration was made on 25 January 1981 (Thirty years on, page 38).
• Mikhail Baryshnikov and Vaslav Nijinsky were not "given to the world" by the Bolshoi theatre company as we stated in an article examining the upheaval at the theatre over the departure of Gennady Yanin, a deputy director of the ballet company. The ballet stars' careers began and flowered with the Mariinsky company (Scandal and intrigue rock the Bolshoi, 23 March, page 19).
• A report on environmental pressure groups calling on governments to abandon new nuclear power stations and large waste dump projects referred to tremors in India ranging up to 6.3 on the Richter scale. Seismologists no longer use this scale, we should have said magnitude 6.3. Similarly, a Pass notes item referred to an earthquake of 8.9 on the Richter scale. To clarify: the "Richter scale", the logarithmic magnitude scale, was defined in 1935 to measure earthquakes in California. It does not, however, work for large earthquakes (greater than magnitude 7) or ones where the epicentre is further than 600km from the point of measurement. It was superseded in 1979 by the more uniformly applicable moment magnitude (Mw) scale (Power plants urged to look at risks, 14 March, page 3; Pass notes No 2,942, The Smiling Sun, 15 March, page 3, G2).