LIST OF PLATES.

Plate.

I. The Aurora during the Ice-pressure To face page 14

II. Aurora seen by Dr. Hayes, 6th January, 1861 ” ” 16

III. Aurora, Guildford, Oct. 24, 1870 ” ” 18

IV. Aurora, Guildford, Feb. 4, 1872; Eclipsed Moon, Aug. 23, 24, 1877 ” ” 20

V. Corona, Graphical Auroræ, Zodiacal Light, &c. ” ” 21

VI. Aurora, Guildford, Feb. 4, 1874; Spectrum des Nordlichts (Vogel) ” ” 22

VII. Aurora, Kyle Akin, Isle of Skye, Sept. 11, 1874 ” ” 24

VIII. Herr Carl Bock’s Lapland Aurora, Oct. 3, 1877 ” ” 25

IX. Compared Aurora and other Spectra. Loomis’s curves of Auroras, Magnetic Declination, and Solar Spots ” ” 59

X. Spectroscope, Micrometer, Tubes ” ” 91

XI. Aurora-spectra, Candle-spectrum ” ” 102

XII. Aurora-spectrum, Solar spectrum, and Candle-spectrum ” ” 104

XIII. Vogel’s Aurora-lines, Aurora-lines near G, and in the red and green ” ” 108

XIV. Aurora, Hydrocarbons, Oxygen ” ” 110

XV. Aurora and Air-tubes, &c. ” ” 115

XVI. Aurora, Phosphoretted Hydrogen, Iron, &c. ” ” 117

XVII. Effect of Magnet on Tubes and Spark ” ” 134

XVIII. Same, and Oxygen-spectrum ” ” 154