[Illustration:
=The Lunar “Crater” Copernicus=
Photographed from Nasmyth and Carpenter's plaster-of-paris model of
the moon.
In this model the topography of the moon is faithfully represented as
seen with powerful telescopes.
]
------------------------------------------------------------------------
Astronomy in a
Nutshell
The Chief Facts and Principles
Explained in Popular Language
for the General Reader
and for Schools
By
Garrett P. Serviss
_=With 47 Illustrations=_
G. P. Putnam's Sons
New York and London
+The Knickerbocker Press+
1912
------------------------------------------------------------------------
COPYRIGHT, 1912
BY
GARRETT P. SERVISS
+The Knickerbocker Press, New York+
------------------------------------------------------------------------
PREFACE
How many thousands of educated people, trained in the best schools, or
even graduates of the great universities, have made the confession: “I
never got a grip on astronomy in my student days. They didn't make it
either plain or interesting to me; and now I am sorry for it.”
The purpose of the writer of this book is to supply the need of such
persons, either in school, or at home, after school-days are ended. He
does not address himself to special students of the subject—although
they, too, may find the book useful at the beginning—but to that vast,
intelligent public for whom astronomy is, more or less, a “mystical
midland,” from which, occasionally, fascinating news comes to their
ears. The ordinary text-book is too overladen with technical details,
and too summary in its treatment of the general subject, to catch and
hold the attention of those who have no special preliminary interest in
astronomy. The aim here is to tell all that really needs to be told, and
no more, and to put it as perspicuously, compactly, and interestingly,
as possible. For that reason the book is called a “nutshell.”
* * * * *
The author has been sparing in the use of diagrams, because he believes
that, in many cases, they have been over-pressed. There is a tendency to
try to represent everything to the eye. This is well to a certain
extent, but there is danger that by pursuing this method too far the
power of mental comprehension will be weakened. After all, it is only by
an intelligent use of the imagination that progress can be made in such
a science as astronomy. The reader is urged to make a serious effort to
understand what is said in the text, and to picture it in his mind's
eye, before referring to the diagrams. After he has thus presented the
subject to his imagination, he may refer to the illustrations, and
correct with their aid any misapprehension. For this reason the cuts,
with their descriptions, have been made independent of the regular text,
although they are placed in their proper connections throughout the
book.
G. P. S.
April, 1912.
------------------------------------------------------------------------
CONTENTS
PART I—THE CELESTIAL SPHERE.
PAGES
Definition of Astronomy—Fundamental Law of the 3-64
Stars—Relations of the Earth to the
Universe—Ordinary Appearance of the Sky—The
Horizon, the Zenith, and the Meridian—Locating
the Stars—Altitude and Azimuth—Circular or
Angular Measure—Altitude Circles and Vertical
Circles—The Apparent Motion of the Heavens—The
North Star and Phenomena Connected with
it—Revolution of the Stars round the
Pole—Locating the Stars on the Celestial
Sphere—Astronomical Equivalents of Latitude and
Longitude—Parallels of Declination and Hour
Circles—“The Greenwich of the Sky”—Effects
Produced by Changing the Observer's Place on the
Earth—The Parallel Sphere, the Right Sphere, and
the Oblique Sphere—The Astronomical Clock—The
Ecliptic—Apparent Annual Revolution of the Sun
round the Earth—Inclination of the Ecliptic to
the Equator: its Cause and its Effects—The
Equinoxes—Importance of the Vernal Equinox—The
Equinoctial Colure—The Solstices—Poles of the
Ecliptic—Celestial Latitude and Longitude—The
Zodiac—The Precession of the Equinoxes: its
Cause and Effects—Revolution of the Celestial
Poles—Past and Future Pole Stars