LAWS OF GOD IN NATURE. 
17 
reflected ray and the rod is exactly equal to the angle made by 
the direct ray and the rod. Armed with these two laws you may 
solve every apparent mystery connected with the reflection of 
light. 
The laws governing the refraction of light—that is, the re¬ 
direction which light takes when it passes from one medium to 
another, as from the air into glass—are only less simple and far- 
reaching than those of reflection. There comes to nearly everybody 
a time of life when they must use spectacles. What does each 
curved piece of glass, each lens, do for us? It so re-directs, or 
makes a bend or break in the direction of, or, to use the best word, 
refracts all the rays of light that are reflected to the eye by an 
object, as to enable the eye to receive those rays as the unimpaired 
eye of childhood or youth receives them. Would you understand 
the action of the simple telescope, or of the double telescope 
commonly termed an opera-glass, or of the stereoscope, or of the 
camera-lucida, or of the photographic camera, or of the magic 
lantern, or of the simple or compound microscope, or of that most 
beautiful of all optical instruments the human eye; or why, 
when we partly immerse a stick in water, “all we have power to 
see is a straight staff bent in a pool ” ? Study the laws of the 
refraction of light. The first of those laws may be expressed by 
saying that the light which is refracted is in the same plane as that 
which shines on the refracting medium, whether the medium be 
water, glass, a gem, or other substance. The second law admits of 
geometrical statement, and has reference to certain characters of the 
angles made by the direct ray and the refracted ray with a common 
perpendicular. The resulting ratio furnishes a quantitative index 
of refraction. Thus water is more refractive than air to the extent 
that the number 1340 is greater than 1000, glass being represented 
by the figures 1530 to 1640 according to its composition, while the 
lovely gem the sapphire would stand at about 1800, and the greatest 
of all brilliantly refracting substances, the diamond, at 2450 to 
2750 according to its chemical purity. 
The great truths or decrees or laws which result in the production 
of all colour in nature can only be glanced at. The sun’s light 
shines on drops of rain which refract, reflect, and so decompose 
the white light into its constituent colours, as to produce a grand 
spectrum, commonly called a rainbow. The water-drops in the 
spray of a fountain or those forced up by the bow of a rapid steam- 
vessel give similar spectra. A prism or wedge of glass gives such a 
spectrum. Certain pigments in nature, as the colouring matter of 
the rose, and certain pigments made by man’s art, as mauve and 
VOL. IV.—PART I. 
2 
