50 Currents of the Ocean. 



fully the absolute command of any extensive territory of the 

 earth over the atmosphere immediately incumbent on it, in point 

 of motion." 



This remark, made with regard to the accelerating effect 

 which the friction of the earth's surface exercises upon the 

 rotatory velocity of the superincumbent atmosphere, applies 

 with equal force to the powerful influence which the conforma- 

 tion of the surface of the solid earth's crust must exercise upon 

 the atmospheric and oceanic currents with which this surface 

 comes in contact. 



Notwithstanding the daily accumulating mass of observa- 

 tions made in every part of the world, dissatisfaction has been 

 frequently expressed at our imperfect insight into the laws 

 which govern meteorological phenomena. Perhaps we look in 

 vain for a direct manifestation of those laws under conditions 

 constantly tending to modify the form under which they are 

 presented to us, and the observer must be content to discover 

 the expression of a general law under the disguise of ever 

 varying and often contradictory phenomena. Every terrestrial 

 area, both on sea and land, has its own system of atmospheric 

 and oceanic currents ; as every part of a continent, every valley 

 has its own climate, subject to the general laws which govern 

 the circulation of currents and the distribution of climate over 

 the whole of our planet. 



Parallelism between Oceanic and Atmospheric Currents. 

 — On account of the more uniform conditions which prevail 

 over oceanic areas in comparison with continental areas, the 

 phenomena of currents are less complicated in the former than 

 in the latter, and can be studied to greater advantage. 



If we consult a wind-chart, we find that the direction of the 

 prevailing currents of air which flow over the surface of the 

 ocean agrees with the direction of atmospheric currents, such 

 as would arise from the unequal distribution of solar heat over 



