the observer’s handbook for 1978 is the seventieth edition. It has now grown to 128 pages: the predictions of total and grazing lunar occultations have been con­ siderably expanded to cover the whole of Canada and the U.S., and about a dozen other sections have been extensively revised and/or expanded.

I thank all those who contributed to the preparation of the 1978 edition: those whose names appear explicitly in the various sections, those mentioned below, and especially the editorial assistant, John F. A. Perkins. Among the many people who have given freely of their advice and assistance are: R. C. Brooks (an improved version of the sidereal time diagram), Terry Dickinson (further expansion of the important “Planets” section), Vic Gaizauskas (advice on eclipses and solar phenom­ ena), Ian Halliday (advice on planetary and miscellaneous astronomical data), Janet A. Mattei (predictions of Algol and δ Cephei, as well as other variable star information), P. B. Robertson (revision of the “Impact Craters” section), T. Van Flandern (advice and assistance with the expansion of the occultation predictions) and Joe Veverka (advice on planetary satellite data). I also thank Helen S. Hogg and R. P. Van Zandt for their many comments and suggestions, and Rosemary Freeman and Lloyd Higgs for their assistance and support. Once again, the David Dunlap Observatory and Erindale College, University of Toronto, provided much- appreciated financial, technical and moral support for the handbook.

My indebtedness to H.M. Nautical Almanac Office, and to the American Ephemeris, is even greater than in past years. Leslie Morrison and his colleagues at H.M.N.A.O. provided all of the predictions of total and grazing lunar occultations, well in advance of our publication deadline; Gordon E. Taylor provided the pre­dictions on planetary occultations [I hope that the results of these latter predictions are as exciting as they were in 1977!].

Finally, I must record, with sadness, the death of Dr. John F. Heard in October 1976. He was a major contributor to this handbook, a leader and counsellor of the R.A.S.C. for forty years, and an outstanding figure in Canadian astronomy.

John R. Percy