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Contents.
Tails.—Repulsive Action of the Sun on Tails of Comets.—Changes of Direction of Tails.—Tails probably hollow cones or hollow cylinders.—Vibration of Tails.—Jets of Light in the heads of Comets.—Formation of Envelopes.—Fans of Light.—Abnormal Changes in the Tails of certain recent Comets.—Swift's Comet of 1892 (i.).—Brooks's Comet of 1893 (iv.).—Observations by Barnard.—Morehouse's Comet of 1908 (iii.).—Speculations as to the formation of Tails.—Bredichin's classification of Tails.—(1) Long straight Rays.—(2) Curved plume-like Trains.—(3) Short, stubby, and sharply-curved brushes of light.—What is the material of which Tails are made?—Speculation on the subject not very profitable.—Electricity and Light-pressure probably co-operating influence.—Summary by Maunder. |
22-37 |
CHAPTER IV.
THE MOVEMENTS OF COMETS.
Periodical Comets.—Non-periodical Comets.—The density of Comets.—The Masses of Comets.—Lexell's Comet.—The risk of collision of Comets with the Earth.—No real danger.—The Influence of Planets on Comets very real.—Special Influence of Jupiter.—List of Comets affected by Jupiter. Comets that are said to be associated with Planets.—The Inquiries made when a new Comet is discovered.—Old Astronomers puzzled by the movements of Comets.—Sir I. Newton's investigations. |
38–45 |
CHAPTER V.
THE DISCOVERY AND IDENTIFICATION OF COMETS.
How Comets are discovered.—The great French Comet-hunter, Messier.—Much Comet-hunting now carried on in America.—Suitable occupation for amateur astronomers.—Designation of Comets.—Appropriation of observers' names to Comets.—Comets only identified by the elements of their orbits.—Physical appearance of Comets no certain proof of identity.—Identity of elements not always conclusive.—Possibility of more than one Comet following the same path.—Photography as an aid to the discovery of Comets.—Ancient Chinese records of great value.—Medals for successful Comet-hunters.—Telegraph codes for transmission of cometary announcements. |
46–57 |
