the observer’s handbook for 1972 is the sixty-fourth edition. In response to sug­gestions from readers, several changes and improvements have been made and a number of errors and omissions in the 1971 edition have been rectified.

My thanks go to all those who assisted in the preparation of this edition: to those whose names appear in the various sections and to my assistant editors Marie Fidler and Peter Tattersall. Special thanks go to Margaret W. Mayall, Director of the A.A.V.S.O. for the predictions of Algol and the variable stars, to Gordon E. Taylor, British Nautical Almanac Office, for the prediction of planetary appulses and occultations, and to Maude Towne and Isabel Williamson for the tables of moonrise and moonset. I also thank the Department of Energy, Mines and Resources, the Astrophysics Branch, National Research Council of Canada, and the David Dunlap Observatory for their assistance and support. Finally, my deep indebtedness to the British Nautical Almanac Office and to the American Ephemeris is gratefully acknowledged.

John R. Percy