Listeners may remember that on March 19 Captain White-Knox, of St. John Ambulance Association gave a general talk on the importance of first-aid knowledge, ' Have you been in an accident ? ' A few days later he broadcast some first-aid ' Do's and Don'ts' on the eve of the Easter Holidays. This evening, on the eve of the Coronation and Whitsun Holidays, he will repeat some of his hints, and give listeners a list of various centres in Great Britain where they may obtain training for themselves.