XIV CONTENTS. 



IV, Ring of Zodiacal Light: Historical account of its recognition, 



&c. Intermittence two-fold, horary (or diurnal) and annual. 

 Distinction to be made between what belongs to the cosmical 

 luminous processes in the ring of the zodiacal light itself, and 

 what to variations in the transparency of the atmosphere. 

 Importance of a long series of corresponding observations 

 within the tropics, at different elevations above the sea up to 

 ten or twelve thousand feet. Reflected glow as in sunset. 

 Comparison, on the same night, with particular parts of the 

 Milky Way. Whether the ring of Zodiacal Light coincides 

 with the plane of the Sun's equator, p. 413 418. 



V. Falling Stars, Balls of Fire, and Meteoric Stones : Most ancient 



chronologically ascertained aerolitic fall, i. e. that of JEgos 

 Potamoi, and influence exerted by it, and by the cosmical ex- 

 planations given of it, on the views of the structure of the Uni- 

 verse conceived by Anaxagoras and Diogenes of Apollonia (be- 

 longing to the later Ionic School) ; Force or impetus of revo- 

 lution counteracting the disposition to fall, centrifugal force and 

 gravitation, p. 419 425, and cli. clii. Notes 681687. 

 Geometrical and physical relations of meteors in sporadical and 

 periodical falls ; Radiation of shooting stars from determinate 

 points of departure ; Mean numbers of shooting stars, spora- 

 dical and periodical, in an hour, in different months, p. 425 

 431, and clii. cliii. Notes 688697. Besides the stream of St. 

 Lawrence, and the recently less considerable November pheno- 

 menon, four or five other periodical falls of shooting stars in 

 the course of the year have been recognised with much probabi- 

 lity, p. 431433, and cliii. cliv. Notes 698 and 699. Height 

 and velocity of meteors, p. 433 435. Physical relations, colour, 

 and trains or tails, processes of combustion ; Magnitude ; Ex- 

 amples of ignition of buildings, p. 436438. Meteoric Stones ; 

 falls of aerolites with a clear sky or after the formation of a small 

 dark meteor cloud, p. 438440, cliv. clvi. Notes 702704. 

 Problematical increase of frequency in shooting stars between mid- 

 night and the early morning hours (horary variation) p. 440. 

 Chemical relations of aerolites ; analogy with the components 

 of telluric kinds of Rock, p. 441446, and clvi. Notes 705709. 



