124 THE OCEAN RIVER 



tinuous currents; and he abandoned science for fantasy when 

 he resurrected the ancient idea that abysses in the sea floor 

 were the ultimate destination of the ocean stream. 



During the eighteenth century the communication of obser- 

 vations and ideas began to speed up; hence, most of the later 

 theories had a much greater basis of fact than those of the sev- 

 enteenth century, and the true nature of wind action became 

 more clearly recognized. Franklin, for instance, was certain 

 that the trade winds were responsible for the Gulf Stream by 

 blowing water westward across the equator and heaping it up 

 against the American continent until it was forced to flow 

 between the islands into the Caribbean and the Gulf of 

 Mexico. 



The forces that keep the Ocean River in its great circular 

 path emerged from the world of fantasy with the aid of two 

 separate but interacting factors. There was a gradual appear- 

 ance of new and improved ways of measuring the flow of 

 water, and at the same time a development of the modern 

 physical sciences that in its turn made possible newer, indirect 

 ways of studying ocean currents. One of the first of the new 

 scientific tools to be applied to the Gulf Stream was the ther- 

 mometer, and its first user, Benjamin Franklin. Franklin's 

 contributions to ocean science did not rest with making charts 

 and with his belief in a simple wind theory of ocean circula- 

 tion, but he pioneered in what is still an important field of 

 oceanography when he used a thermometer to locate the Gulf 

 Stream by means of its characteristic warmth. With typical 

 ingenuity he also adapted a wooden barrel by fitting it with 

 valves in order to collect water samples at depths of 100 feet 

 beneath the surface. In this way he was able to show that the 

 deeper waters are colder than those above. 



The thermometer was used in navigation for finding the 

 limits of the warm currents — though, as we shall see, even 



