SIR WILLIAM ROWAN HAMILTON, the eminent mathematician of Dublin, has, of all writers ancient and modern, most fittingly characterized the ideal science of astronomy as man's golden chain connecting the heavens to the earth, by which we "learn the language and interpret the oracles of the universe."

The oldest of the sciences, astronomy is also the broadest in its relations to human knowledge and the interests of mankind...

THE present volume has been prepared with a double purpose, and upon a plan somewhat unusual. First, an effort has been made to meet the wishes of the rdinary reader who may desire to inform himself as to the present state of astronomic science, or to secure a simple explanation of the many phenomena constantly exhibiting themselves in the universe about him ; and the further purpose has been to produce a satisfactory textbook for use in high schools and colleges.

THE object of this book is to give an account of the science of Astronomy, as it is known at the present day, in a manner acceptable to the general reader.

THE present treatise is a condensed edition of the Astronomy of the American Science Series. The book has not been shortened by leaving out anything that as essential, but by omitting some of the details of practical astronomy, thus giving to the descriptive portions a greater relative extension.

I MUST PREFACE these pages by a few words of explanation. The decay of my eye-sight has within the last year incapacitated me from reading or writing. Cut off by this affliction from my usual mental employments, I have found relief and occupation to my thoughts in dictating these essays to a short-hand riter. This mode of writing will excuse any inaccuracies or mistakes which I may have committed.

WAEFIELD PARK, BRACKNELL:
December 1, 1871.

ASTRONOMY, it has been said, is the oldest and the noblest of the sciences. Yet it is one of the few sciences for which most present-day educators seem to find little, if any, room in their curriculum of study for the young, in spite of its high cultural value. It is, we are told, too abstruse a subject for the youthful student. This is doubtless true of theoretical or mathematical astronomy and the practical astronomy of the navigator, surveyor and engineer, but it is not true of general, descriptive astronomy. There are many different aspects of this many-sided science, and some of the simplest and grandest truths of astronomy can be igrasped by the intelligent child of twelve or fourteen years of age...

THE following work is designed principally for the use of those who desire to pursue the study of Astronomy as a branch of liberal education. To acilitate its use by students of different grades, the subject-matter is divided into two classes, distinguished by the size of the type, and the volume is thus made to contain two courses.

THE present work grew out of articles contributed to McClure's Magazine a few years since on the Unsolved Problems of Astronomy, Total Eclipses of the Sun, and other subjects. The interest shown in these articles suggested an exposition of the main facts of astronomy in the same style. The result of the attempt is now submitted to the courteous consideration of the reader.

THE Science of Astronomy is sublime and beautiful. Noble, elevating, consoling, divine, it gives us wings, and bears us through Infinitude. In these thereal regions all is pure, luminous, and splendid. Dreams of the Ideal, even of the Inaccessible, weave their subtle spells upon us. The imagination soars aloft, and aspires to the sources of Eternal Beauty.

From time to tune during many years publications have been issued describing the instruments and methods used by the Coast and Geodetic Survey in the etermination of time, longitude, latitude, and azimuth. The general aim has been to provide a working manual which would serve as a guide to the observer in the field and the computer in the office in carrying on the astronomic work of the Survey in a systematic manner. The exhaustion of previous editions and the introduction of new instruments and methods have made necessary the successive editions, in each of which much has been repeated from the preceding one.