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.
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 22
From photographs taken at the Yerkes Observatory.
MARS, OCTOBER 5, 1909 23
Photo: Mount Wilson Observatory.