10 NATURE-STUDY LESSONS. 



(e) Try to verify the statement that sound travels 



about 1 1 20 ft. per second. 

 (/") Calculate the distance of the engine or of the 



flash of lightning referred to above. 



E. The Organ of Hearing. 



18. (rt) Examine the outer ear. 



{b) Observe the adaptation of its form. 



{c) Note the entrance to the inner ear and how 



the entrance is protected. 

 {d) Describe tlie ear, noting in your description 



each of the above points. Illustrate your 



description by drawings. 



19. What is the use of each part of the ear? 



20. If possible, examine the receiver of a telephone 

 and compare its parts with those of the ear. 



F. Attention and Hearing. 



21. («) Why is one in a room where a clock is going 



not always conscious of its ticking ? 

 (J)) Give heed to all the sounds you can hear in a 



minute and make a list of them. 

 {c) Why do you not always hear all the sounds? 



G. How to Train the Sense of Hearing. 



22. (a) Distinguish different birds by their notes. 



{b) Examine several objects of different weights 

 and different degrees of hardness, then, by 

 listening to the sound that each makes when 

 it is dropped on the floor by the teacher, 

 tell what it is. 



(c) With eyes closed, recognize different compan- 



ions by their utterance of a word. 



(d) Distinguish different kinds of whistles, as of 



locomotives, threshing engines. 



(e) Endeavor to distinguish different sounds. 



