10. That heat is an original force, which, reducing all matter to a gaseous state during the early periods, is now stored up for manifestation in matter.

11. Because heat was believed to be the Creative Force.

12. An amount equal to that yielded by the combustion of a layer of anthracite ten feet thick, covering the whole surface of the sun.

13. One twenty-three hundred millionth of it.

14. Chemical action, mechanical action as by friction, compression and percussion, and electric action.

15. 4,000° F.

16. Considerably greater. The exact intensity has not yet been determined.

17. Either because the molecules now in vibration require more room for their increased oscillations, or because the atoms being now farther apart expand the molecules to greater size; though both of these conditions may conjointly produce that result.

18. By heating metallic bars passing through them, which on expanding and lengthening are firmly secured; on cooling, they contract, thus drawing the walls towards each other, straightening, strengthening, and holding them in position.

19. So that, on cooling, they shall contract tightly upon the wheel, and thus strengthen and protect it.

20. Heat of sufficient intensity to separate the atoms of molecules, even causing complete molecular change and disintegration, thus producing decomposition of the substance to which it is applied.

21. At least 4,000° F.

22. In daylight, solid matter becomes luminous at about 1,000° F., Gases at about 2,000° F.

23. Full "red heat," however, has a temperature of 1,000° F. An object, as a piece of iron, heated in a darkened room, first begins to glow at about 700° F. White heat varies in temperature from 1,400° to 3280° F.

24. It is readily convertible into its equivalent: light, electricity, chemical action, motion, and vice versa. Therefore, like all force, it is as indestructible as matter, though capable of assuming different forms. This principle is called "the correlation of forces," and "the conservation of energy." 25. One pound of water, in cooling one degree F., will give out suf

ficient heat to raise, by expansion, 772 pounds one foot high; or 772 pounds, in falling a distance of one foot, cause the evolution of enough heat to raise one pound of water one degree F.

26. Seven times that existing in the luminous portion.

27. Three ways, namely: by conduction, convection, and radiation. 28. The passage of heat from particle to particle of a substance, until the whole mass is of the same degree of temperature. This takes a measurable length of time.

29. Solids are the best conductors.

30. Silver, copper, gold, brass, tin, and iron are the best conductors, silver standing at the head of the list in this respect. Gases, liquids, glass, all porous bodies, such as fur, feathers, snow, and wool, are poor conductors of heat.

31. Pour alcohol upon some water in a vessel; when the alcohol is lighted, it will burn until it is consumed, but the water will not be heated to any appreciable depth.

32. Being poor conductors, the heat of the body cannot pass away. The air between the meshes of the goods adds to the non-conducting power of the material.

33. Being less porous, they contain less air in their texture, and hence facilitate the passage of heat.

34. In falling, it catches and becomes mixed with large quantities of air, thus acquiring the properties of a non-conductor.

35. Because, being porous, it is a poor conductor of heat.

36. Asbestos is one of the best non-conductors of heat, and does not transmit the heat of the iron to the hand.

37. By applying heat underneath the vessel containing them. The lower particles become heated and rise, cooler particles take their place; these in turn rise, repeating the process until the whole mass is brought to the same temperature. This process is called convection.

38. The temperature at which a liquid bursts into vapor. It depends upon the character of the liquid, the elevation of the place above the sea level, and the atmospheric pressure. Water at the sea level boils at 212°, at an elevation of 9,000 feet it boils at 194°. Mercury boils at 662° F.

39. The emission of heat in straight lines in every direction from a heated or burning body.

40. Enough to melt a layer of ice covering the whole earth to the depth of 114 feet.

41. If a heated body be placed in a cold room, it will at once radiate its heat, every object in the room receiving more or less, until each becomes of the same temperature.

42. The polished metals, the same as for light.

43. Yes; but probably more upon the molecular character or constitution of an object.

44. An instrument for measuring higher degrees of temperature than can be indicated by an ordinary thermometer.

45. An instrument for measuring temperature.

46. By marking the freezing and boiling points of water, which, under similar conditions, are always at the same temperatures, respectively. The interval, or space, between these points is differently divided by different makers.

47. Fahrenheit: The freezing point of water marked at 32°, the boiling point at 212°.-Centigrade: The freezing point marked at zero, the boiling point at 100°.-Réaumur: The freezing point marked at zero, the boiling point at 80°.

48. Fahrenheit to Centigrade: From the Fahrenheit degrees subtract 32°, and take five-ninths of the remainder.-Centigrade to Fahrenheit: Take nine-fifths of the Centigrade degrees, and add 32°.-Fahrenheit to Réaumur: From Fahrenheit degrees subtract 32°, and take four-ninths of the remainder.-Réaumur to Fahrenheit: Take nine-fourths of the Réaumur degrees, and add 32°.

49. Different bodies of equal weight at the same temperature have different quantities of heat.-In three ways. 1. Method by melting ice; 2. Method of mixtures; 3. Method by cooling.

The

50. It is the heat in bodies, not recorded by the thermometer. 51. Fourteen inches, at the centre covered by a slip-joint. The contraction, Jan. 6, 1884, was twelve inches, thermometer below zero. contraction at each end was seven inches.-Col. Paine, Chief Engineer. 52. By the passage of an enormous amount of heat into the latent or insensible form.

53. Intense cold.

54. A prominent factor in removing the line of difference between the vaporized and liquid portion of substances under great heat and pressure.

55. Because it expands. Water reaches its maximum density at 39° F. As the temperature falls below that point, and the process of congelation converts the liquid to the solid or crystalline form, the resulting body occupies more space, and expands with sufficient force to fracture and break the strongest vessels.

56. When drops of water come in contact with a heated metallic surface, they collect a globular form and move rapidly about. Underneath them is formed a cushion of heated air, or steam, which prevents their direct contact with the metal. Should the temperature of the metal be lowered, the cushion of steam will be destroyed, and the water will disappear in steam so suddenly as to cause an explosion. This is known as the spheroidal state of water, and may often be the cause of explosion in steam boilers.

57. Cast-iron which melts at 2786° F.

58. 98° F.

59. Mercury freezes at 391° below zero.

60. Gold which melts at 2016° F.

61. The temperature for hatching eggs is 104° F.

62. Usually "white heat," varying from 1,400° to 3,280° F. Col. R. G. Ingersoll's body was cremated at Fresh Pond, Long Island, July 26, 1899. Temperature 2,075° F.

3. To what height does the atmosphere extend?

4. How is this height determined?

5. Is the atmosphere of equal density throughout its whole extent ?

6. Why does smoke sometimes ascend in a straight line from the

chimney?

7. Why does air force its way through doors and windows, pass to the fireplace, and up through the chimney?

8. Why do bubbles, after rising in the air, fall or burst?

9. Why can balloons ascend in the air?

10. How high can a balloon rise, and how great a weight can it carry? 11. Why do balloons burst, after reaching a certain altitude? 12. How are gossamer spiders enabled to float through the air?

13. What is the weight of air compared with an equal bulk of water? 14. What is the pressure of the atmosphere on a square inch of surface? 15. What is the amount of its pressure on a full-sized human body? 16. Why do we not notice this enormous pressure? 17. State the limits and causes of its variations. 18. Name the estimated amount of its pressure on the surface of the 19. Why do we make two openings in a barrel of vinegar, before we can draw it? [no water escape?

[entire globe.

20. Place a paper over a glass of water, and invert the glass. Why does 21. Why does walking in clayey soil tire us so soon?

22. Why do not parachutes fall rapidly to the earth?

23. Upon what principle does the action of the diving-bell depend?

24. What are caissons? In what operations are they used?

25. Describe the "Pneumatic Despatch" and the "Pneumatic Railway." 26. How much does 100 cubic feet of water weigh?