174 Mr. Hinds on Climate in connexion 



light during the day, that this small decrease of temperature 

 is so keenly felt. 



Range of temperature is also much aiFected by local causes, 

 as the vicinity of forests, sandy plains, and mountain ranges, 

 which elevate or depress the sensible heat. In the northern 

 regions a high temperature is accumulated by the continuance 

 of the sun above the horizon, and correspondingly depressed 

 in its absence ; but on other occasions the range will be found 

 to increase as the mean temperature diminishes. At sea the 

 range is much smaller than on land, attributable to the equal- 

 izing power of the ocean. In the trades there is scarcely a 

 variation of a few degrees in twenty-four hours; in higher 

 latitudes it is greater, but is perhaps not more than half what 

 it would be on the land. 



In the subjoined table, the relation of the range of tem- 

 perature to the latitude and the mean heat is shown. The 

 agency of local causes is also visible in the great range at 

 Astrakan in proportion to its mean heat ; and again at Sidney 

 compared with the Cape of Good Hope, both in nearly the 

 same parallel : — 



Sandwich islands... Lat. 21° 40' N. Mean temp. 75° Annual range 29° 



Sidney 33 51 S 70 



Cape of Good Hope ... 33 56 67-5 



Columbia River 46 N 54 



Astrakan 46 21 



London 51 31 51 



Kinfauns 56 23 47 



Greenland 



79 



51 



74 



130 



79 



58 



138 



The highest temperature ever recorded to have taken place 

 occurred in Africa ; here, at Fezzan, it was observed on one 

 occasion to be 125°*5, and at Belbeis in Egypt 125°; both 

 these are supposed to have been produced by a wind carrying 

 minute particles of heated sand from the desert*. Under 

 these circumstances Humboldt saw it at 114°*5 in South 

 America. In August, at Bagdad, the thermometer has been 

 knowii to reach 120°. Dr. Heberden witnessed the highest 

 temperature in England, when, in the month of July, the 

 thermometer stood at 98°. Sir Edward Parry has observed 

 the greatest excess in the other extreme ; at Melville Island, 

 in the month of February, the cold was so intense, that the 

 thermometer descended to 55° below zero. Several observers 

 have likewise seen mercury freeze in the northern parts of 

 America and Asia, which requires a depression of 72° below 

 the freezing point. It so happens that this range of excesses 

 is exactly equal to that between the congelation and boiling 



* On more than one occasion I have known the sand near the sea-shore, 

 supporting an appropriate vegetation, heated to 128°. 



