THE RAINBOW. 
Behold yon bright ethereal Bow, 
With evanescent beauties glow ; 
The spacious arch streams through the shy, 
Deck'd with each tint of Nature's dye ; 
Refracted sunbeams, through the shower, 
A humid radiance from it pour ; 
Whilst colour into colour fades 
With blended lights and softening shades. 
The Rainbow is one of the most beautiful appearances in nature, and 
is visible when the sun is shining brightly in one part of the heavens, 
while, at the same time, a shower is falling in the opposite direction. 
The observer, placing himself with his back to the sun, sees on the rain- 
clouds opposite a majestic arch brightening into the most lovely colours, 
blended in perfect harmony. While he is yet gazing, if there be much 
rain, another arch appears, exterior to the first but fainter in colour. 
Both arches exhibit the same series of colours, namely, red, orange, yel- 
low, green, blue, indigo, and violet ; but their arrangement is different, 
for while in the inner arch the lower edge is violet and the upper red, in 
the outer arch the lower edge is red and the upper violet. 
The cause of this beautiful phenomenon is to be found in the fact, 
that the light of the sun is made up of three colours, namely, red, yellow 
and blue. In passing through the drops of rain, these colours are sepa- 
rated, and bent more or less, from the usual straight direction of the 
sun's rays. Some of the colours, however, admit of being bent more 
than others ; the blue is bent out of its course more than the yellow, 
and this again more than the red, and thus the colours appear separately. 
These colours, by mingling together, form the other tints of the Rain- 
bow. A similar cause produces the colours of dew-drops, which often 
appear like differently-coloured gems sparkling among the grass. 
When the rain-cloud is of small extent, only a part of the bow is vi- 
sible : when the clouds overspread a large portion of the sky, a perfect 
bow appears. Sometimes, indeed, the bow may be traced across a por- 
tion of blue sky, or it may apparently rest upon the ground. In the 
former case, there are vapours in the air of too light a nature to be visible 
to the naked eye, but sufficient to refract and reflect the rays of light ; 
in the latter, the drops of rain adhering to the grass and foliage, produce 
the same effect. When seen to the greatest perfection, the Rainbow 
appears as a perfect semicircle, and it cannot exceed this unless the spec- 
tator be on elevated ground. In mountainous and stormy regions, rain- 
bows are often seen to great advantage. 
Rainbows are sometimes produced by the moon as well as by the sun ; 
but these lunar Rainbows are generally white, cloudy, or greyish, and 
very seldom exhibit the colours of the solar Rainbow. A coloured bow 
similar to that produced by rain, is sometimes seen in the spray of a foun- 
tain or of a waterfall, and also in mists that lie low upon the ground. 
The beauty of this phenomenon is not the only reason why we should 
look upon it with great interest. The Rainbow was appointed by God 
himself as the sign of the covenant of mercy, made with Noah and with 
all mankind after the Flood. The words in which this declaration was 
made to mankind, are recorded in the Book of Genesis, chapter ix. 
v. 11 to 16. 
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