488 SCIENCE OF HOME AND COMMUNITY 



5. Pith rays. 



6. Knots. 



B. The appearance of woods depends on the way in which 



they are cut. 



1. A cut made at right angles to the length is called a trans- 



verse section. 



2. A cut made lengthwise, at about right angles with the 



rings, that is, nearly parallel with the pith rays, is 

 called radial, or quarter-sawed. 



3. A cut made tangent to the rings, that is, at right angles 



with the pith rays, is called tangent or bastard. 

 Find three pieces of wood, one cut in each of these ways, and 

 make three labeled drawings to show whatever features men- 

 tioned under A may be present in each section. 



C. Make a drawing of a piece of the desk about three inches 



square, and label the parts that show. In which of the 

 three ways was it cut? Look at a number of samples 

 of wood in chairs, tables, etc., and determine the cut. 



Forests as protective covers. As a protective cover, the 

 forest serves two important purposes : first, it regulates the 

 flow of streams ; and second, it prevents erosion of the hill- 

 sides. On the forest floor is a thick layer of black humus, 

 composed of the decaying leaves and twigs which fall every 

 year to the ground. This humus covers the soil like a blanket 

 and exerts a very important influence through its effect in 

 controlling the water supply of streams. When rain falls 

 some evaporates at once and goes back into the air ; some 

 runs off on the surface and quickly gathers into streams ; 

 the rest soaks slowly down into the soil and gradually comes 

 out again through springs and streams and through evapo- 

 ration from the leaves of plants. The humus and mossy 

 vegetation act as a sponge. They absorb a large amount of 

 water and give it out again gradually during the dry spells 

 between rains. Thus they tend to prevent floods just after 

 a rain and to prevent the drying up of the streams during 

 the dry weather. Forests tend, therefore, to give streams 



