ORNER OF THE BERLIN MAP BY THE USE OF WHICH
GALLE FOUND NEPTUNE " " 82

VI. ASTRONOMERS ROYAL _Frontispiece_

VII. GREAT COMET OF NOV. 7, 1882 _To face page_ 122

VIII. THE OXFORD NEW STAR " " 142

IX. NEBULOSITY ROUND NOVA PERSEI " " 146

X. SUN-SPOTS AT GREENWICH, FEB. 18 AND 19, 1894 " " 158

XI. SUN-SPOTS AT GREENWICH, FEB. 20 AND 21, 1894 " " 162

XII. NUMBER OF SUN-SPOTS COMPARED WITH DAILY RANGE
OF MAGNETIC DECLINATION AND DAILY RANGE OF
MAGNETIC HORIZONTAL FORCE " " 164

XIII. GREENWICH MAGNETIC CURVES, 1859-60 " " 166

XIV. GREENWICH MAGNETIC CURVES, 1841-1860 " " 166

XV. SUN-SPOTS AND TURNS OF VANE " " 170

ERRATA

Page 133, line 27, _for_ "200 stars" _read_ "200 stars per hour."

" 145, See note on page 220.

" 146, bottom of page. This nebulosity was first discovered by Dr.
Max Wolf of Heidelberg. See _Astr. Nachr._ 3736.

" 181, line 17, _for_ "observation" _read_ "aberration."

ASTRONOMICAL DISCOVERY

CHAPTER I

URANUS AND EROS

[Sidenote: Popular view of discovery.]

Discovery is expected from an astronomer. The lay mind scarcely thinks of
a naturalist nowadays discovering new animals, or of a chemist as finding
new elements save on rare occasions; but it does think of the astronomer
as making discoveries. The popular imagination pictures him spending the
whole night in watching the skies from a high tower through a long
telescope, occasionally rewarded by the finding of something new, without
much mental effort. I propose to compare with this romantic picture some
of the actual facts, some of the ways in which discoveries are really
made; and if we find that the image and the reality differ, I hope that
the romance will nevertheless not be thereby destroyed, but may adapt
itself to conditions more closely resembling the facts.

[Sidenote: Keats' lines.]

The popular conception finds expression in the lines of Keats:--

Then felt I like some watcher of the skies
When a new planet swims into his ken.

Keats was born in 1795, published his first volume of poems in 1817, and
died in 1821. At the