REVIEW. 303 



9. If two tuning-forks vibrating respectively 256 and 259 times 

 per second be simultaneously sounded near each other, what phe- 

 nomena would follow ? 



10. A musical string, known to vibrate 400 times a second, gives 

 a certain tone. A second string sounded a moment later seems to 

 give the same tone. When sounded together, two beats per second 

 are noticeable, (a.) Are the strings in unison? (&.) If not, what is 

 the rate of vibration of the second string ? 



11. If a tone be produced by 256 vibrations per second, what num- 

 bers will correspond to its third, fifth and octave respectively ? 



12. If a tone be produced by 264 vibrations per second, what 

 number will represent the vibrations of the tone a fifth above its 

 octave ? 



Recapitulation. In this section we have considered 

 Sympathetic Vibrations and Sounding 

 Boards ; the Telephone and Phonograph ; 

 Reinforcement and Resonance ; Interfer- 

 ence and Beats ; Vibrations of Strings ; the 

 Musical Scale ; Absolute Pitch ; Funda- 

 mental Tones ; Overtones ; the Quality of 

 Sounds; Musical Instruments. 



KEVIEW QUESTIONS AND EXERCISES. 



1. (a.) Define sound ; (&.) give its cause ; (c.) mode of propagation 

 and (d.) velocity. 



2. (a.) Give the rate at which sound is transmitted in air. (6.) 

 How is it affected by temperature ? (c.) Give the law of Reflection. 

 (d.) How may it be illustrated ? 



3. (a.) What is capillary attraction ? (&.) Give three illustrations 

 of the importance of capillary action in the operations of nature. 



4. (a.) Describe an experiment showing the expansibility of the 

 air. (6.) Give the laws of the Pendulum. 



5. (a.) On what does the loudness of sound depend? (&.) How 

 may the pitch of strings be varied ? (c.) Give the relative number 

 of vibrations in the major diatonic scale, and (d.) find the number of 

 vibrations for A 2 . 



6. (a.) Represent by a diagram, a lever of the first class, in which 

 one pound will balance five. (6.) Give the laws of falling bodies. 



7. Explain the Artesian well by a diagram. 



