PREFACE

The Handbook for 1949 is the 41st issue. During the past decade its circulation has increased from 1500 to 5500. This year, for the second time, some advertisements of astronomical accessories are inserted. The Officers of the Society appreciate this assistance at the present time of financial difficulty. With regret the price has been raised to 40 cents.

Four circular star maps 9 inches in diameter at a price of one cent each, and a set of four maps plotted on equatorial co-ordinates at a price of ten cents, are obtainable from the Director of University Extension, University of Toronto, Toronto 5.

Celestial distances given herein are based on the standard value of 8".80 for the sun’s parallax, not on the more recent value 8".790 determined by Sir Harold Jones. Among the alterations and additions this year are:

1. Algol. Olin J. Egger’s epoch 2432520.6303 and period 2.86731525d., as published in the Astrophysical Journal, 1948.
2. Standard Time Zones. A new map including all of the U.S.A.
3. Sunrise, sunset; moonrise, moonset. The tables now include a wider range of latitude, taking in the southern states.
4. Sun-spots. A table of solar rotation numbers for observers of sun-spots, and an ephemeris for physical observations of the sun.

Dr. F. S. Hogg, the Assistant Editor, as in recent years, assumed the responsi­ bility of preparing this volume and to him the chief credit of its success is due; but sincere thanks are tendered to all those names mentioned in the book. Our deep indebtedness to the British Nautical Almanac and the American Ephemeris is thankfully acknowledged.

C. A. Chant.
David Dunlap Observatory,
Richmond Hill, Ont., November, 1948.