A DARK NEBULA Taken in 1920 with the aid of the largest telescope in the world.
One of the first photographs taken by the Mount Wilson telescope. There are dark nebulæ and bright nebulæ. Prof. Henry
Norris Russell, against the British theory, holds that the dark
nebulæ preceded the bright nebulæ. Photo: Prof. Hale
Slowly by degrees as one million of years followed another, this
