Structure of the Photosphere 143

CHAPTER III

RECENT SOLAR ECLIPSES

Expeditions to Spain--Great Indian Eclipse--New Method of Viewing
Prominences--Total Eclipse Visible in North America--Spectrum of the
Corona--Eclipse of 1870--Young's Reversing Layer--Eclipse of
1871--Corona of 1878--Varying Coronal Types--Egyptian
Eclipse--Daylight Coronal Photography--Observations at Caroline
Island--Photographs of Corona in 1886 and 1889--Eclipses of 1896,
1898, 1900, and 1901--Mechanical Theory of Corona--Electro-Magnetic
Theories--Nature of Corona 166

CHAPTER IV

SOLAR SPECTROSCOPY

Chemistry of Prominences--Study of their Forms--Two
Classes--Photographs and Spectrographs of Prominences--Their
Distribution--Structure of the Chromosphere--Spectroscopic Measurement
of Radial Movements--Spectroscopic Determination of Solar
Rotation--Velocities of Transport in the Sun--Lockyer's Theory of
Dissociation--Solar Constituents--Oxygen Absorption in Solar
Spectrum 194

CHAPTER V

TEMPERATURE OF THE SUN

Thermal Power of the Sun--Radiation and Temperature--Estimates of
Solar Temperature--Rosetti's and Wilson's Results--Zoellner's Method
--Langley's Experiment at Pittsburg--The Sun's Atmosphere--Langley's
Bolometric Researches--Selective Absorption by our Air--The Solar
Constant 216

CHAPTER VI

THE SUN'S DISTANCE

Difficulty of the Problem--Oppositions of Mars--Transits of
Venus--Lunar Disturbance--Velocity of Light--Transit of
1874--Inconclusive Result--Opposition of Mars in 1877--Measurements of
Minor Planets--Transit of 1882--Newcomb's Determination of the
Velocity of Light--Combined Result 227

CHAPTER VII

PLANETS AND SATELLITES

Schroeter's Life and Work--Luminous Appearances during Transits of
Mercury--Mountains of Mercury--Intra-Mercurian Planets--Schiaparelli's
Results for the Rotation of Mercury and Venus--Illusory
Satellite--Mountains and Atmosphere of Venu