

HOT EQUATORIAL NIGHTS. 71 



often as still and hot as that found inside one of these 

 houses. The great heat of the night, therefore, prevents 

 many people who feel the heat greatly, from obtaining 

 sound and refreshing sleep. The minimum tempera- 

 ture of the 24 hours, it must be remembered, merely 

 as a rule represents that of the last hour or two before 

 sunrise, and by no means that of the greater part of 

 the night, during which it stands considerably higher. 

 Sound sleep is therefore in many cases only enjoyed 

 during the morning hours: this serious matter is a 

 frequent cause of trouble in these climates. 



On the other hand, the intense solar temperatures 

 which we hear of as being registered occasionally, do 

 not as a rule occur in the intertropical regions at 

 all. Where high temperatures, such as those exceeding 

 100 F. in the shade, do occur in the tropics, they 

 usually do so in dry districts, such as the deserts of 

 the Soudan, during the prevalence of hot winds, and 

 under circumstances when the atmosphere ceases to 

 exert that power with which it is endowed, in moister 

 regions, of tempering the excessive heats, in consequence 

 of the absence of aqueous vapour; or the temperature 

 may be affected by the refraction of heat from sand, 

 rocks, and other exceptional causes : and thus, phe- 

 nomenally high temperatures may be produced. 



The highest solar temperatures generally occur in 

 the zones of dry country which extend in belts around 

 the earth wherever there is land, somewhat to the 

 northward of the Tropic of Cancer, and to the south- 

 ward of the Tropic of the Capricorn. These therefore 

 may be regarded as the zones of maximum solar 

 temperatures. Or possibly, it may be, still further to 

 the north and south, extreme heats may occur, on 



