COLOR 161 



we get white light again. The rainbow is a natural spectrum 

 into which light is broken up by falling raindrops. Small 

 rainbows may often be seen in the spray from waterfalls, 

 lawn sprinklers, and the like. The misty halos sometimes 

 noticed encircling the moon and regarded as the forerunners 

 of stormy weather are due to similar causes. Other examples 

 of refracted sunlight are the brilliant colors of the sky at sun- 

 rise and sunset. The composition of light may be studied 

 by means of the spectroscope. This consists essentially 'of a 



FIG. 59. The spectroscope. (Tower, Smith and Turton.) 



prism with means for magnifying and measuring the rays of 

 light passing through it. All luminous bodies give out char- 

 acteristic rays. When a gas is heated enough to glow, it 

 produces a set of colored lines in the spectroscope, which are 

 known as its spectrum. By means of the spectroscope, the 

 light from distant stars has been examined and the elements 

 composing them identified. Only a few of the vibrations com- 

 ing to us in sunlight are perceptible to the eye. Beyond the 

 red end of the solar spectrum, as it is called, are still slower 

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