the observer’s handbook for 1973 is the sixty-fifth edition. The major change in this edition is the inclusion of data on grazing occultations over Canada. These data were supplied by Mr. L. V. Morrison of the British Nautical Almanac Office.

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) Litchinsky and Chris Smith. Special thanks go to Margaret W. Mayall, Director of the A.A.V.S.O., for the predictions of Algol and of 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 for the maps of time zones, 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