A Handbook of Descriptive and Practical Astronomy: The sun, planets, and comets

PREFACE TO THE THIRD EDITION.

(EXTRACT.)

DVANTAGE has been taken of the call for a new edition

ADVAN

of this work to subject the whole, from the first page to the last, to a searching revision. This has proved to be a task of unusual difficulty and labour, in consequence of the astonishing developement which has taken place in the science of Astronomy during the last ten years. And moreover the demands on my time made by professional work have of late been such as to render it very difficult for me to give to Astronomical Studies that close attention which is indispensable if the author of an Astronomical Book would keep his pages up to date and so do justice alike to himself and his readers. It is not open to doubt that this is a matter which sits very lightly upon the consciences of some writers of Text-books. There is scarcely a single page which has not been, to a greater or less extent, dressed up, or in some way amended, with the object of making its statements more accurate in substance or intelligible in diction.

I have to acknowledge a great amount of very useful advice and assistance from observers in all parts of the world, most of them total strangers to me, many of them being persons I had never heard of until the receipt of their letters. Indeed, the letters that I have received, especially from the United States of America, have been a very gratifying encouragement to me to persevere in improving this work in every possible way.

6. F. C.

December, 1876.

PREFACE TO THE SECOND EDITION.

(EXTRACT.)

STRONOMY is not cultivated in this country, either as a

study or as a recreation, to the extent that it is on the Continent of Europe and in America. And there is a lack of works in the English language which are at one and the same time attractive to the general reader, serviceable to the student, and handy, for purposes of reference, to the professional Astronomer; in fact, of works which are popular without being vapid, and scientific without being unduly technical.

The foregoing observations will serve to indicate why this book has been written. Its aim, curtly expressed, is, general usefulness.

Preferring facts to fancies, I have endeavoured to avoid all those mischievous speculations on matters belonging to the domain of Recondite Wisdom, which have within the last few years borne such pernicious yet natural fruits.

In regard to the matter of bringing up to date, it is believed that the present volume will compare favourably with any of its contemporaries.

March, 1867.

6. F. C.

PREFACE TO THE FIRST EDITION.

ENGI

(EXTRACT.)

NGLISH literature, abundant though it may be in other respects, is undoubtedly very deficient in works on Astronomy. Our choice is limited either to purely elementary books, few in number, on the one hand; or to advanced treatises, of which there is a similar paucity, on the other. The present work is designed to occupy a middle position between these two classes: to be attractive to the general reader, useful to the amateur, and ‘handy' also, as an occasional book of reference, to the professional astronomer.

In pursuance of the plan laid down from the first, theoretical matter is, as a rule, excluded; but in many cases it has been thought desirable not to abide with perfect strictness by this limitation.

Finally, it is hoped that this book may be the means of inducing some, at least, to interest themselves in the study of that noble Science, which in so conclusive a manner shows forth the wonderful Wisdom, Power, and Beneficence of the Great Creator and Omnipotent Ruler of the Universe.

6. F. C.

EAST-BOURNE, SUSSEX:

August, 1861.

CONTENTS.

Astronomical importance of the Sun.-Solar parallax.-The means of determining

it. By observations of Mars.-By Transits of Venus.-Numerical data.-

Light and Heat of the Sun.-Gravity at the Sun's surface.-Spots.-Descrip-

tion of their appearance.-How distributed.-Their duration.-Period of the