OYSTER CULTURE IN AMERICA. 83! 



dred fathoms deep, and that every source of heat and of 

 radiation be removed, so that its fluid temperature becomes 

 constant and uniform throughout. On such a globe, the 

 equilibrium remaining undisturbed, there would be neither 

 wind nor current. Let us now suppose that all the waters 

 within the tropics to the depth of one hundred fathoms 

 suddenly becomes oil. The aqueous equilibrium of the 

 planet would thereby be disturbed, and a general system 

 of currents and counter-currents would immediately com- 

 mence the oil, in an unbroken sheet on the surface, run- 

 ning towards the poles, and the water, in an under-current, 

 towards the equator. The oil is supposed, as it reaches 

 the polar basin, to be converted into water, and the water 

 to become oil as it crosses the tropic, rising to the surface 

 in the hot region, and returning as before. Thus, without 

 zvind, we should have a perpetual and uniform system of 

 tropical and polar currents, though without wind Sir John 

 Herschell maintains we should have no ' considerable cur- 

 rents whatever in the sea.' : 



Captain Maury then proceeds to show how, by the 

 rotatory movement of our planet, these currents, instead of 

 flowing due north and south, are thrown to the right ; and 

 that, if, in addition to this cause for deflection, you intro- 

 duce a series of obstacles in the shape of continents, 

 islands, and shallows, you would easily create those cross- 

 currents, those variations in volume and velocity, which are 

 met with in the circulation of the ocean of our planet ; and 

 he concludes by asking whether the cold waters of our 

 northern regions, and the warm waters of the Gulf of 

 Mexico, made specifically lighter by tropical heat, do not, 

 in their present system of currents, represent in a great 

 degree the relation of the imaginary oil and water. 



