17. What is the velocity of sound in air at 0° C. ? What is it at 20° C. ? What at 60° Fah. ?
18. What is the velocity of sound in water ? How has it been determined?
19. State what you know of the velocity of sound in solids.
20. Describe an experiment, which illustrates the fact, that solids are, as a rule, good conductors of sound.
21. A person observes that ten seconds elapse between a flash of lightning and the succeeding thunder clap. What is the approximate distance of the thunder cloud from the observer ?
22. A vessel at sea is seen to fire one of its guns. Thirty-five seconds afterwards, the report is heard. How far off is the vessel ? (Temperature 25° C.)
23. What is the use of the External ear ?
24. Describe the relative positions in the ear of the (1) Tympanum, (2j Fenestra Ovalis, (3) Fenestra Rotunda.
25. How is the vibratory motion of the Tympanum transmitted to the Fenestra Ovalis ?
26. In what part of the internal ear are the Fibres of Corti situated? What is supposed to be their function ?
27. What is the Eustachian Tube? What would be the result of this tube becoming stopped up ?
28. The cavity of the Middle Ear is in most persons, completely separated from the external air by the Tympanum; but occasionally there is an aperture in this latter. Does this necessarily affect the hearing? Give reasons for your answer.
29. What is the special function of the labyrinth ?
30. What are the three elements which define a musical sound ?
31. What is the physical cause of variation in pitch? Describe a simple experiment in support of your answer.
32. What is meant by the vibration number of a musical sound?
33. Mention three of the most accurate methods of experimentally determining the vibration number of a given musical sound.
84. Describe the Wheel Syren.
35. What are the disadvantages of Cargnard de la Tour's Syren ?
36. Describe the construction of Savart's Toothed Wheel.
37. Describe the Sonometer or Monochord.
38. Describe Helmholtz's or Dove's Double Syren.