

TERRESTRIAL HEAT. 



CHAPTEE II. 



47. Sources of external heat. 43. Solar heat. 49. Its quantity ascer- 

 tained. 50. Heat at sun's surface. 51. Temperature of celestial 

 spaces. 52. Quantity of heat supplied by them. 53. Summary of 

 heat supplied. 54. Winds. 55. Produced by rarefaction and com- 

 pression. 56. Sudden condensation of vapour. 57. Hurricanes. 

 58. Their cause. 59. Waterspouts. 60. Evaporation. 61. Satura- 

 tion of air. 62. May arise from intermixing strata. 63. Effect of 

 pressure. 64. Dew. 65. Hoarfrost. 66. Artificial ice. 67. Fogs 

 and clouds. 68. Rain. 69. Its quantity. 70. Snow. 71. Hail. 

 72. Hailstones. 73. Extraordinary hailstones. 



47. WHATEVER may be the sources of internal heat, the globe 

 of the earth would, after a certain time, be reduced to a state of 

 absolute cold, if it did not receive from external sources ths 

 quantity of heat necessary to repair its losses. If the globe were 



LARDXER'S MUSEUM OF SCIENCE. o 81 



No. 36. 



