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Lunar Rainbows. 



Tints. 

 Sundogs. 

 Halos. 



Solar halo; lunar halo; color of sky within halo. 

 Precipitation of Vapor of the Air. 



Origin of dew; most favorable conditions for formation. More 

 abundant in country or town. 

 Hoar Frost. 



Formation; crystalline structure; where most abundant. 

 Fog. 



Cause; what time of day most common; occurrence on high or low 

 land; near a body of water or land. 



LIGHT. 



Light plays so important a part in the economy of nature that the 

 children should have some idea of its laws and influences. 

 1. Sources of Light. 



'Sun, stars, chemical and mechanical action, electricity, phosphor- 

 escence. Compare combustion without light and combustion ac- 

 companied with light. 



Light by friction; light by percussion. 



Indian's manner of making fire by friction; striking a stone with 

 a piece of steel. Spark in old flint lock guns. 



Distinguish between transparent, translucent, and apaque bodies; 

 self-luminous, non-luminous, and illuminated bodies. 



Light travels in a straight line through one medium. Distinguish 

 between reflected, refracted, and diffused light. Do we see most 

 things with reflected or diffused light? 



In connection with the study of light a sheep's eye or a pig's eye 

 should be dissected, and the internal structure compared with that of 

 the human eye. Carefully remove all flesh and fat. Observe color and 

 texture of coats and optic nerve. With a sharp knife carefully cut 

 through the sclerotic coat, and gently press the contents out on a 

 piece of glass. The watery substance is the aqueous humor, the clear, 

 transparent, firm humor the crystalline lens, and the white jelly-like 

 substance the vitreous humor. The dark circular portion is the iris. 

 Observe the two sets of muscles radiating and circular. 

 The Human Eye. 

 (a) Protections. 



Bony socket, cushion of fat, brows, lids, lashes, oil glands at 

 base of lashes, tear gland, tear duct. 



