Solar Eclipse Calculation (Modern and Accurate Western Methods)

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Preface

The method of calculating the several Circumstances of the Solar Eclipse given in this’ book is a modern one’ based’ on the modern and accurate astronomy and astronomical tables. The circumstances’ of an. eclipse are- the time of the beginning, the middle and the end of the eclipse, magnitude of: the eclipse, together with the times of the two internal contacts in the’ case of a total solar and ‘lunar eclipses .and also of the annular eclipse or ring - forming eclipse ill the case of the Sun only and the points of contacts. The methods given in the ancient Hindu Astronomical books (or Siddhantas or Karana granthas or Vakya Systems) are very-crude and do not give satisfactory’ results for .the circumstances of an eclipse. This book is’ a self-contained: one and ,does not require the help of other books if the ordinary method of multiplication, and division is’ used. If, on the other hand, Logarithmic method is used a good book of tables containing (1) Logarithms of Numbers up to :1,00,000 or so and (2) Logarithms of trigonometrical Functions of Sine, Cosine, Tanient and Cotangent upto seven or five decimal places is required.

The method of ordinary multiplication and division: is better than the method of trigonometrical ‘tables, as it gives better results, though it is long, tedious, pains-taking and time-consuming. The employment of logarithmic tables is only a device to save labour and time; but this method is a little inferior and. can be adopted for our ordinary purposes. The logarithmic method must be used only by those who know the use of logarithms, and who want to learn logarithms and use them and not by others, Whenever’ you feel any difficulty or doubt while calculating a quantity (deducible from a Formula or Equation) by employing logarithms, it is always better that you calculate that quantity only by using the ordinary multiplication and division which will’ give correct results, as you will be more familiar with ordinary -multiplication and division than with logarithms. I have also given, in this book, some useful information or instructions about logarithmic tables.

In producing this book, I have consulted some useful and modern books on the" Theory of Eclipses." My thanks are due to William Chauvenet, R. Buchanan, Bessel, Gingel, Schraam, Oppolzer, Barlow and Bryan. Robert Ball, Simon Newcomb, Godfray, Hymers, Watson, and Doo Little,: whose works. I have studied to acquire my knowledge about eclipses. My thanks tare specially due to (1) (Mr. Wenceslao Benitez, the Director of the observatory of Marina San Fernando in Spain and his ‘staff, (2) to the Astronomers-Royal. of the Observatory of Washington and Greenwhich and their staff (3) to the Officers m charge of the Kodaikanal Observatory and their staff (4) to Sri V. Kapaleeswaran U. A., and .Sri K. M. Easwarasawrni B. A., Asst. Meteorologists & Sri Kulkarni Librarian-all of the office of the Regional Meteorological Centre Madraso-as they have helped me with furnishing me with either necessary and rare books or instructions etc. about eclipses-which were of great help to me ill producing this book in the present .form, ,My thanks are .also-due: to Mr. P. A. Palani Mudaliar-Proprietor of Aruaa Printers, 70 Padavattamman Koil St. Purasawakkam. Madras-for ‘having neatly ,and quickly executed this work. I have’ been long cherishing the idea of producing a book first in Tamil (and then ‘in English)’ from about 1925 AD and I will consider that my ‘ambition has been-realised, if this book is really found useful to the students of practical astronomy and Panchanga or Almanac-makers or producers. Salutations to the Modern Astronomers.

N. B., The reader is requested to carry out the corrections especially in the’ tables before beginning the actual calculation, otherwise, all- his labour and time will become useless.