SURROUNDINGS OF THE HOME 275 



Exercises 



1. What is meant by vulcanized rubber? What changes are produced in 

 the rubber by vulcanizing it? 



2. Describe how the rubber stamps in common use are made? 



3. To what uses is old rubber put? Why has it no greater market value? 

 About what is the market value of the pure gum now? 



4. Read all available material upon the turpentine industry of southeastern 

 United States. Then write a short description of it, including the care of 

 the trees, the processes of manufacture, the products and their varied uses. 



6. What are "mercerized cotton" fabrics? What especial advantage arises 



from this treatment? 

 6. Formerly what two plants furnished most of the dyes for cloth? How 



were different colors obtained from the same dye? At about what date 



were the "coal tar dyes" first produced? 



BIRDS AROUND OUR HOMES 



For beginners to study birds from pictures and printed 

 descriptions is even more unsatisfactory than it is to study 

 trees from books only. In making studies of birds it is likely 

 that the English sparrow will be at hand anywhere. In 

 rural districts and smaller towns other birds are likely to be 

 plentiful. In the zoology departments of some high schools 

 there may be collections of stuffed birds, and mounted skele- 

 tons. The study of certain of these in detail may be exceed- 

 ingly profitable for comparisons of types of bird life. Many 

 city parks have extensive aviaries and museums. Any ex- 

 tended study of birds constitutes a division of Zoology. 

 However, one need not be a scientist in order to have an 

 extended knowledge of the forms and ways of birds, and to 

 enter into the full enjoyment of bird life. 



Birds as distinguished from other animals are characterized 

 by a covering of feathers, and by a modification of the fore- 

 limbs into wings that are more or less useful for flying. Like 

 man birds are bipeds, and the young experience difficulty in 

 learning to walk as well as in becoming able to fly. For a 

 considerable time after being hatched from the eggs young 



