ILLUSTRATIONS 



FACING 

 PACE 



THE GREAT SCARLET SOLAR PROMINENCES, WHICH ARE SUCH A NOTABLE 

 FEATURE OF THE SOLAR PHENOMENA, ARE IMMENSE OUTBURSTS OF 

 FLAMING HYDROGEN RISING SOMETIMES TO A HEIGHT OF 500,000 MILES 



Coloured Frontispiece 



LAPLACE ............ 10 



PROFESSOR J. C. ADAMS ......... 10 



Photo: Royal Astronomical Society. 



PROFESSOR EDDINGTON OF CAMBRIDGE UNIVERSITY .... 10 

 Photo: Elliot & Fry, Ltd. 



THE PLANETS, SHOWING THEIR RELATIVE DISTANCES AND DIMENSIONS 11 



THE MILKY WAV 14 



Photo: Harvard College Observatory. 



THE MOON ENTERING THE SHADOW CAST BY THE EARTH . . .14 



THE GREAT NEBULA IN ANDROMEDA, MESSIER 31 . . . .15 



From a photograph taken at the Yerkes Observatory. 



DIAGRAM SHOWING THE MAIN LAYERS OF THE SUN . . . .18 



SOLAR PROMINENCES SEEN AT TOTAL SOLAR ECLIPSE, MAY 29, 1919. 



TAKEN AT SOBRAL, BRAZIL . . . . . . . .18 



Photo: Royal Observatory, Greenwich. 



THE VISIBLE SURFACE OF THE SUN . . . . . . .19 



Photo: Mount Wilson Observatory. 



THE SUN PHOTOGRAPHED IN THE LIGHT OF GLOWING HYDROGEN . . 19 

 Photo: Mount Wilson Observatory. 



SUN, FEBRUARY 5, 1905 ......... 22 



Photo: Royal Observatory, Greenwich. 



THE AURORA BOREALIS (Coloured Illustration) ..... 20 

 Reproduced from The Forces of Nature (Messrs. Macmillan) 



THE GREAT SUN-SPOT OF JULY 17, 1905 ...... 22 



Yerkes Observatory. 



SOLAR PROMINENCES .......... 19 



From photographs taken at the Yerkes Observatory. 



MARS, OCTOBER 5, 1909 -..... 23 



Photo: Mount Wilson Observatory. 



vii 



