Chapter I: Preface

The reason for this book’s appearance may be set forth in a few words. A long course of reflective scrutiny of the lunar surface with the aid of telescopes of considerable power, and a consequent familiarity with the wonderful details there presented, convinced us that there was yet something to be said about the moon, that existing works on Astronomy did not contain. Much valuable labour has been bestowed upon the topography of the moon, and this subject we do not pretend to advance. Enough has also been written for the benefit of those who desire an acquaintance with the intricate movements of the moon in space; and accordingly we pass this subject without notice. But very little has been written respecting the moon’s physiography, or the causative phenomena of the features, broad and detailed, that the surface of our satellite presents for study. Our observations had led us to some conclusions, respecting the cause of volcanic energy and the mode of its action as manifested in the characteristic craters and other eruptive phenomena that abound upon the moon’s surface. We have endeavoured to explain these phenomena by reference to a few natural laws, and to connect them with the general hypothesis of planet formation which is now widely accepted by cosmologists. The principal aim of our work is to lay these proffered explanations before the students and admirers of astronomy and science in general; and we trust that what we have deduced concerning the moon may be taken as referring to a certain extent to other planets.

Some reflections upon the moon considered as a world, in reference to questions of habitability, and to the peculiar conditions which would attend a sojourn on the lunar surface, have appeared to us not inappropriate. These, though instructive, are rather curious than important. More worthy of respectful consideration are the few remarks we have offered upon the moon as a satellite and a benefactor to the inhabitants of this Earth.

In reference to the Illustrations accompanying this work, more especially those which represent certain portions of the lunar surface as they are revealed by the aid of powerful telescopes, such as those which we employed in our scrutiny, it is proper that we should say a few words here on the means by which they have been produced.——

During upwards of thirty years of assiduous observation, every favourable opportunity has been seized to educate the eye not only in respect to comprehending the general character of the moon’s surface, but also to examining minutely its marvellous details under every variety of phase, in the hope of rightly understanding their true nature as well as the causes which had produced them. This object was aided by making careful drawings of each portion or object when it was most favourably presented in the telescope. These drawings were again and again repeated, revised, and compared with the actual objects, the eye thus advancing in correctness and power of appreciating minute details, while the hand was acquiring, by assiduous practice, the art of rendering correct representations of the objects in view. In order to present these Illustrations with as near an approach as possible to the absolute integrity of the original objects, the idea occurred to us that by translating the drawings into models which, when placed in the sun’s rays, would faithfully reproduce the lunar effects of light and shadow, and then photographing the models so treated, we should produce most faithful representations of the original. The result was in every way highly satisfactory, and has yielded pictures of the details of the lunar surface such as we feel every confidence in submitting to those of our readers who have made a special study of the subject. It is hoped that those also who have not had opportunity to become intimately acquainted with the details of the lunar surface, will be enabled to become so by aid of these Illustrations.

In conclusion, we think it desirable to add that the photographic illustrations above referred to are printed by well-established pigment processes which ensure their entire permanency.

CONTENTS.

PAGE

CHAPTER I.
ON THE COSMICAL ORIGIN OF THE PLANETS OF THE SOLAR SYSTEM. 1
Origination of Material Things—Celestial Vapours—Nebulæ—Their
vast Numbers—Sir W. Herschel’s Observations and
Classification—Buffon’s Cosmogony—Laplace’s Nebular
Hypothesis—Doubts upon its Validity—Support from Spectrum
Analysis

CHAPTER II.
THE GENERATION OF COSMICAL HEAT. 11
Conservation of Force—Indestructibility of Force—Its
Convertibility into Heat—Dawn of the Doctrine—Mayer’s
Deductions—Joule’s Experiments—Mechanical Equivalent of
Heat—Gravitation the Source of Cosmical Heat—Calculations
of Mayer and Helmholtz—The Moon as an Incandescent
Sphere—Not necessarily Burning—Loss of Heat by
Radiation—Cooling of External Crust—Commencement of
Selenological History

CHAPTER III.
THE SUBSEQUENT COOLING OF THE IGNEOUS BODY. 19
Cooling commenced from Outer Surface—Contraction by
Cooling—Expansion of Molten Matter upon
Solidification—Water not exceptional—Similar Behaviour of
Molten Iron—Floating of Solid on Molten Metal—Currents in
a Pot of Molten Metal—Bursting of Iron Bottle by
Congelation of Bismuth within—Evidence from Furnace
Slag—From the Crater of Vesuvius—Effects of Contraction of
Moon’s Crust and Expansion of Interior—Production of
Ridges and Wrinkles—Theory of Wrinkles—Examples from
shrivelled Apple and Hand

CHAPTER IV.
THE FORM, MAGNITUDE, WEIGHT, AND DENSITY OF THE LUNAR GLOBE. 31
Form of Moon—Not perfectly Spherical—Bulged towards
Earth—Diameter—Angular Measure—Linear Measure—Parallax of
Moon—Distance—Area of Lunar Sphere—Solid Contents—Mass of
Moon—Law of Gravitation—Mass determined by Tides and other
Means—Density—How obtained—Specific Gravity of Lunar
Matter—Force of Gravity at Surface—How determined—Weights
of similar Bodies on Earth and Moon—Effects of like Forces
acting against Gravity on Earth and Moon

CHAPTER V.
ON THE EXISTENCE OR NON-EXISTENCE OF A LUNAR ATMOSPHERE. 39
Subject of Controversy—Phenomena of Terrestrial Atmosphere—No
Counterparts on Moon—Negative Evidence from Solar
Eclipses—No Twilight on Moon—Evidence from Spectrum
Analysis—From Occultations of Stars—Absence of Water or
Moisture—Cryophorus—No Reddening of Sun’s Rays by Vapours
on Moon—No Air or Water to complicate Discussions of Lunar
Volcanic Phenomena

CHAPTER VI.
THE GENERAL ASPECT OF THE LUNAR SURFACE. 51
Pre-Telescopic Ideas—Human Countenance—Other supposed
Resemblances—Portrait of Full Moon—Permanence of
Features—Rotation of Moon—Solar Period and Solar Day on
Moon—Libration—Diurnal—In Latitude—In Longitude—Visible
and Invisible Hemispheres—Telescopic Scrutiny—Galileo’s
Views—Features Visible with Low Power—Low Powers on small
and large Telescopes—Salient
Features—Craters—Plains—Bright Streaks—Mountains—Higher
Telescopic Powers—Detail Scrutiny of Features
therewith—Discussion of High Powers—Education of
Eye—Highest practicable Power—Size of smallest Visible
Objects

CHAPTER VII.
TOPOGRAPHY OF THE MOON. 65
Reasons for Mapping the Moon—Early Maps—Labours of
Langreen—Hevelius—Riccioli—Cassini—Schroeter—Modern
Maps—Lohrman’s—Beer and Maedler’s—Excellence of the
last—Measurement of Mountain Heights—Need of a Picture
Map—Formation of our own—Skeleton Map—Table of conspicuous
Objects—Descriptions of special
Objects—Copernicus—Gassendi—Eudoxus and
Aristotle—Triesnecker—Theophilus, Cyrillus, and
Catharina—Thebit—Plato—Valley of the
Alps—Pico—Tycho—Wargentin—Aristarchus and
Herodotus—Walter—Archimedes and the Apennines