CHAPTER IV. 



TERRESTRIAL CLIMATES, TEMPERATURES, AND 

 ATMOSPHERIC DISTURBANCES. 



Value of a Knowledge of Climate to Travellers. Ignorance that 

 formerly Prevailed on this Subject. Examples from British Military 

 and Colonial Records. In the Worst Climate there is a Comparatively 

 Healthy Season. Slight Losses in Recent Expeditions, due to Going 

 in the Healthy Season. The Walcheren Expedition, Causes of the 

 Great Losses. Principal Factors in the Creation of Climate. Temperature 

 as Modified by Elevation. General Contour of the Earth's Surface. 

 Ratio of Temperature to Elevation. Mean Temperature of the Equatorial 

 Zone. Swampy and Unhealthy Coasts. The Highlands of the Interior. 

 Tropical Sanitary Stations. Climate of Mexico. Beauty and Luxuriance 

 of Its Forest Scenes. The Tropical Rains. Yellow Fever. Sanatorium 

 of Jalapa. The Climatic Range of Yellow Fever. Yellow Fever at 

 Lisbon. In the West Indies and Brazil. Effects of " Moisture " on 

 Temperature. Depressing Effects of "Damp Heat." Dry Air and 

 Extreme Temperatures. Remarkable Instances of Great Heat. Dry 

 Air and Cool Nights. Coincidence of the Mahometan Faith with Dry, 

 Hot Climates. People of Colour. The Arabs. Influences of Climate 

 on the History of Man. Droughts. The Phenomena of Dry Atmosphere. 

 Therapeutic Effects of Dry Cold. " Equable Climates " necessarily 

 " Moist Climates." The Winds. Created by the Sun's Heat. The 

 Trade Winds. "The Doldrums." Land Winds. The Uses of Deserts. 

 Monsoons. Indian Droughts and Famines. Equatorial Currents in the 

 Celestial Altitudes. Rains. The Coming-up of a Sub-Tropical Rainstorm. 

 Outburst of an Equatorial Thunder Storm. Value of Forests in 

 Preventing Destructive Effects of Torrential Rains. Remarkable 

 Instances of Great Rainfalls. Sudden Inundations Caused by Torrential 

 Rains. The Coming down of the Great River Atbara. Danger of 

 Encamping in Dry River Beds. Great American Rainstorms. The 

 Coming down of an American Prairie Flood. Destruction of U.S. 

 Army Camps by Sudden Floods. Supposed Causes of These Floods. 

 Waterspout in Paris. Instances of Great Thunder Storms. Traveller 

 Killed by Lightning. Thirteen Oxen Struck Dead in a Heap. The Bursting 

 of the Indian Monsoon. Ideas of the Ancients on the Sources of Rain. 

 The Superior Waters Above the Firmament. The Teachings of Modern 

 Science upon Rain. The Vapour-Carrying Power of the Winds. 

 Probable Cause of Blue Colour of the Sky. Evaporation in Visible 

 Form. Great Atmospheric Disturbances. Tracks of Hurricanes Generally 

 Follow Areas of Extreme Temperatures. Revolving Storms. The 

 "Lull" of the Storm. Rules for Avoiding Cyclones at Sea. Force and 



