This arises from the fact that the sodium flame possesses the remarkable property of cutting off the sunlight which was on its way to those particular lines; so that, though the sodium contributes some light to the lines, yet it intercepts a far greater quantity of the light that would otherwise have illuminated those lines, and hence they became darker with the sodium flame than without it.
"The Story of the Heavens"
Robert Stawell Ball
Our line of pickets intercepts the Leesburg turnpike at Drainesville and extends to the Potomac, a distance of about twenty miles.
"Three Years in the Federal Cavalry"
Willard Glazier
He is watchful and intercepts you, once more offering the sapphire, while declaring that he is poor and cannot afford to keep it, but must let you have it for the forty pounds you offered; actual necessity compels him to sacrifice it at that price, etc.
"The Pearl of India"
Maturin M. Ballou