110 SCIENCE OF COMMON THINGS. 



Countries destitute of rain. Aunual amount of rain. Annual eva'poration. 

 6Q9 Why are these countries destitute of rain ? 



The cause of this scarcity is to be sought for in the 

 peculiar conformation of the country. 



In Peni, parallel to the coast, and at a short distance from the sea, is 

 the lofty range of the Andes, the peaks of which are covered with per- 

 petual snow and ice. The prevailing wind is an east wind, sweeping 

 from the Atlantic to the Pacific across the continent of South America. 

 As it approaches the west coast, it encounters this range of mountains, 

 and becomes so cooled by them that it is forced to precipitate its moist- 

 ure and passes on to the coast almost devoid of moisture. In Egypt and 

 other desert countries, the dry sandy plains heat the atmosphere to such 

 an extent that it absorbs moisture, and precipitates none. 



7OO Are there some districts in which it may be said to always rain ? 



In some portions of Guiana it rains for 'a great por- 

 tion of the year. The fierce heat of the tropical sun 

 fills the atmosphere with vapor, which returns to the 

 earth again in constant showers, as the cool winds of the 

 ocean flow in from the higher latitudes. 



7*O1 How great a quantity of water is supposed to be annually precipi- 

 tated as rainf 



The amount is calculated to exceed seven hundred 

 and sixty millions of tons 



7*OJ3 Was this whole, amount raised by evaporation into the atmosphere f 



Certainly ; the daily amount of water raised by 

 evaporation from the sea alone amounts to no less than 

 one hundred and sixty-four cubic miles, or about sixty 

 thousand cubic miles annually. 



7*O3 What is the daily amount of evaporation from the sea between the 

 Cape of Good Hope and Calcutta f 



During the months of October and November, it is 

 known to average three quarters of an inch daily from 

 the w r hole surface. 



7*04 Is the climate of New England and the Northern United States 

 drier than that of England and Central Europe ? 



It is / and this fact exercises an important influence 

 upon many professions and callings, tainters find that 

 their work dries quicker in New England than in Cen- 

 tral Europe. Cabinet-makers here are obliged to use 

 thicker glue, and watchmakers animal instead of vege- 

 table oil. 



