a beam of light reflected from a thin mirror vibrated by the voice; the beam falling with varying intensity upon a receiver of selenium connected in circuit with a small battery and a telephone receiver. variations in the intensity of the light reproduce the sounds.

The

48. The process of coating various metals with silver or other metals. The object to be plated is hung in a solution of cyanide of silver from the negative pole, while from the positive pole (which is also immersed in the solution) is hung a silver plate. The electric current, passing through the solution from the negative to positive pole, deposits the silver on the article to be plated.

49. It is the application of electricity in the treatment of diseases. Continuous or Galvanic currents have a beneficial action in breaking up and decomposing morbid products; their action on nerve centers and nerves is strengthening. Interrupted and interrupted-induced or Faradic currents are more powerful and act on nerves and muscles; they have a pain killing effect and are used in the neuralgias.

50. Unit of resistance, the Ohm; Current, the Ampere; Electromotive force, the Volt; Quantity, the Coulomb; Capacity, the Farad; Power, the Watt; Induction, the Henry.

51. Electrolysis is the process of decomposing a substance by electricity. It is used in extracting metals from ores and in refining.

52. Sixteen volts and one two-thousandth ampere; less energy than is required to ring a small bell.

53. From 12 miles an hour on street railways to 45 miles an hour on heavy railways.

54. Over 100,000 miles, or enough to girdle the earth four times. 55. By measuring the electricity necessary to charge the remaining unbroken part, or its resistance.

56. Over 1,000,000.

57. More than 770,000.

58. By a circuit through the car roof inducing a current in wires on poles along the track.

59. British Columbia and New Zealand, via America and Europe. 60. A powerful arc light in a reflector which renders its rays parallel. The glare from them has been seen 170 miles at sea in cloudy weather.

1. What is the largest natural division of land in the world?

2. What and where is the most elevated range of mountains? 3. Which is the highest mountain in the world?

4. What volcano has the greatest eruptive force?

5. What and where is the loftiest active volcano?

6. Which is the largest body of fresh water on the globe?

7. What and where is the greatest inland sea?

8. Which and where is the largest river?

9. Which is the most remarkable whirlpool?

10. Where are the most wonderful natural echoes? 11. Where is the highest tide found?

12. What desert stands first in area?

13. Where is the most remarkable natural bridge?
14. What country is first in precious stones?
15. What is the largest diamond in the world?
16. Where is gold found in the largest quantities?
17. Where are the silver mines, of greatest extent?

18. Where are found the largest deposits of copper ?

19. Where is iron most abundant? 20. Where are the largest lead mines?

21. Where are the most extensive salt mines?

22. Which country is richest in petroleum?

23. Which is the largest island in the world? 24. What is the most stupendous waterfall?

25. Where is the highest waterfall?

26. Where are the most wonderful geysers?

27. What, and where, is the most extraordinary natural basalt pier?

28. What country has the largest standing army?

29. What country has the largest navy?

30. Where is the largest telescope?

31. Where is the longest line of railroad?

32. Where is the greatest length of marine cable?

33. Where is the most famous lighthouse in the world?

34. Where is the most famous lighthouse in the United States?

35. Where is the largest city park in the United States?

36. What city park has the most extended area?

37. Where is the largest suspension bridge in the world?

38. What and where is the most extensive fortress?

39. What is the strongest fortress? 40. Which city covers the most ground?

41. Which is the most northern city? 42. Which is the most lofty city? 43. Where is the oldest city? 44. Where is the hottest city?

45. Which is the most wicked city?

46. What are the largest audience rooms of the world?

47. Name and give the dimensions of the largest ship in the world.

48. What and where is the longest tunnel?

49. What government possesses the greatest territorial area?

50. What and where is the highest monolith?

51. Where is the largest bell?

52. Where is the largest and most comprehensive library?

53. Which and where is the most extensive wall?

54. What and where is the largest cathedral?

55. Where is the largest university?

56. Where and which is the greatest pyramid?

57. Where is the longest ship canal in the world?
58. Which is the longest canal in the United States?
59. What country has the greatest extent of railroad?
60. What country pays its ruler the largest salary?

61. Which are the five healthiest cities in the United States?

62. What is the population of the world?

63. What is the most wonderful feat of telegraphy on record?

64. Where is the most curious tower?

65. What cave surpasses the Mammoth Cave, Kentucky, in number and

variety of stalagmites and stalactites?

66. In what part of the world are the largest trees found?

67. What and where is the longest tubular bridge?

68. Which is said to be the largest clock ever made?