LESSONS IN PHYSICS. 85 



that light traveling with the inconceivable velocity of 186,000 

 miles per second would be fifty years or more in traversing the 

 profound space, yet with the spectroscope we can analyze that 

 light and make it tell what substance sent it out. 



The rainbow is a beautiful and gigantic solar spectrum, which 

 has been formed by the refracting power of thousands of rain- 

 drop prisms. The bow is seen when the sun is back of the ob- 

 server, and sometimes a second bow may be seen outside of the 

 primary one. The primary bow is formed by light that enters 

 the upper part of the drop, is refracted, reflected and refracted 



again to the observer. The second bow is formed by the light 

 which enters the lower part of the drop, is refracted, reflected 

 twice, then refracted to the observer. (See Fig. 20.) R indicates 

 red ray, V violet ray and S" the sun. 



The white light of the sun falls upon all bodies alike. This 

 light is decomposed in different ways by different bodies, some of 

 it being absorbed and some reflected. One body is red because it 

 reflects the red rays, absorbing the others; another is blue be- 

 cause it reflects only the blue rays, absorbing the others. The 

 foliage of plants receives the sun's white light, decomposes it, 

 reflecting only the green rays. The petals of the rose decompose 

 the sunlight, reflecting to us the colors peculiar to itself. A body 



