104 INTRODUCTION TO GENERAL SCIENCE 



a. 1305:101-102. Twilight. 



6. 1804 : 356. Cause of Twilight. 



76. TRANSMISSION OF LIGHT SHADOWS 



Objects which allow light to pass through them undimmed 

 are called transparent. If the light is much diminished, so 

 that only a little shines through dimly, the object is called 

 translucent. If no light can pass through a body, it is called 

 opaque. When no light passes through an object, it casts a 

 shadow which has the same outline as the object. Therefore 

 we conclude that light travels in straight lines. The brighter 

 the light, the denser is the shadow. 



References : 



1. 1304:238-239. Transmission of Light through the At- 



mosphere. 



2. 1601 : 8. Transmission of Light. 



3. 1803:391. Shadows. 



4. 1803 : 409-410. Why Light Travels in Straight Lines. 



a. 1801:190-192. Shadows. 



b. 1802:262. Shadows. 



c. 1804:323-324. Shadows. 



d. 1805 : 215-216. Transmission of Light. 



e. 1805:220-221. Shadows. 

 /. 1806:142-143. Shadows. 

 g. 1807:260-261. Shadows. 

 h. 1808:374-375. Shadows. 



i. 1809 : 276-278. Shadows Pinhole Camera. 



77. ECLIPSES 



All planets, including the moon and the satellites of the 

 other planets besides the earth, shine by light reflected from 

 the sun. Most of the stars shine by their own light; that is, 

 they are all bodies like our sun, although at a very great dis- 



