uch pains have been taken to trace the
origin of ideas, often obscurely enunciated long before they came to
resound through the scientific world, and to give to each individual
discoverer, strictly and impartially, his due. Prominence has also been
assigned to the biographical element, as underlying and determining the
whole course of human endeavour. The advance of knowledge may be called
a vital process. The lives of men are absorbed into and assimilated by
it. Inquiries into the kind and mode of the surrender in each separate
case must always possess a strong interest, whether for study or for
example.

The acknowledgments of the writer are due to Professor Edward S. Holden,
director of the Washburn Observatory, Wisconsin, and to Dr. Copeland,
chief astronomer of Lord Crawford's Observatory at Dunecht, for many
valuable communications.

London, _September_, 1885.

CONTENTS

_INTRODUCTION_

page
Three Kinds of Astronomy--Progress of the Science during the
Eighteenth Century--Popularity and Rapid Advance during the Nineteenth
Century 1

PART I

_PROGRESS OF ASTRONOMY DURING THE FIRST HALF OF THE NINETEENTH CENTURY_

CHAPTER I

FOUNDATION OF SIDEREAL ASTRONOMY

State of Knowledge regarding the Stars in the Eighteenth Century--
Career of Sir William Herschel--Constitution of the Stellar System--
Double Stars--Herschel's Discovery of their Revolutions--
His Method of Star-gauging--Discoveries of Nebulae--Theory of their
Condensation into Stars--Summary of Results 9

CHAPTER II

PROGRESS OF SIDEREAL ASTRONOMY

Exact Astronomy in Germany--Career of Bessel--His _Fundamenta
Astronomiae_--Career of Fraunhofer--Parallaxes of Fixed
Stars--Translation of the Solar System--Astronomy of the
Invisible--Struve's Researches in Double Stars--Sir John Herschel's
Exploration of the Heavens--Fifty Years' Progress 27

CHAPTER III

PROGRESS OF KNOWLEDGE REGARDING THE SUN

Early Views as to the Nature of Sun-spots--Wilson's Observations and
Reasonings--Sir William Herschel's Theory of the