The theory of light is so undetermined that neither the views of Newton, nor those of Huyghens, can be said to be exclusively adopted. Writers upon natural philosophy seize hold of either or both of those theories, as they present themselves more or less favourably in the explanation of natural phenomena. In "The Reason Why," as we have to speak of the effects of light rather than of its cause, we shall avoid, as far as possible, the doubtful points. But let no one be discouraged by the fact that the theory of light, as, indeed, of all the imponderable agents, is imperfectly understood. Rather let us rejoice that there are vast fields of discovery yet to be explored; and that light, the most glorious and inspiring element in nature, invites us from the sun, the moon, and the stars, and from the face of every green leaf and variegated flower, to search out the wonders of its nature, and further to exemplify the goodness and wisdom of God.
"And God said, Let there be light: and there was light."
452. What is the distance of the sun from the earth?
Ninety five millions of miles.
453. At what rate of velocity does light travel?
At the rate of 192,000 miles in a second, through our atmosphere; and 192,500 miles in a second through a vacuum.
454. How long does light take to travel from the sun to the earth?
Eight minutes and thirteen seconds.