Page:The story of the comets.djvu/68

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34

The Story of the Comets.

Chap.

(1.) Long straight rays.
(2.) Curved plume-like trains.
(3.) Short, stubby, and sharply curved brushes of light.

Tails which belong to Bredichin's first type are formed of matter upon which the Sun's repulsive action is supposed to

Fig. 26.

BREDICHIN'S THREE TYPES OF COMET TAILS.

be 12 or more times greater than the attractive action due to Gravitation; so that the particles quit the head of the comet with a relative velocity which is gradually increased as they recede, until it becomes enormous. The straight rays noticed

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