L60 STEPPES AND DESERTS. 



the Isthmus of Panama to the northern part of Mexico, 

 opposes a barrier to the farther continuance of this move- 

 ment- of the waters, and thus the current is constrained to 

 assume a northerly course off Yeragua, and thence to follow 

 the windings of the coast of Costa Rica, Mosquito, Cam- 

 peachy, and Tabasco. The waters which enter the Mexican 

 Gulf between Cape Catoche of Yucatan and Cape San 

 Antonio of Cuba, after completing a great rotatory move- 

 ment or circuit, by Yera Cruz, Tamiagua, the mouth of 

 the Rio Bravo del Norte, and that of the Mississipi, 

 force their way northwards through the Bahama Channel, 

 and re-issue into the open ocean. Here they form the well- 

 known " Gulf Stream," a current or river of warm and rapidly 

 moving water, flowing in an oblique or diagonal direction 

 carrying it farther and farther from the North American 

 coast. Ships from Europe bound for this coast, when 

 uncertain in respect to their longitude, are enabled by 

 this oblique direction of the current to direct their course, 

 as soon as they reach the Gulf Stream, by observations of 

 latitude only. The position of this great current was first 

 indicated with accuracy by Franklin, Williams, and Pownall. 

 Prom the 4 1st degree of latitude, the river of warm 

 water, which has been gradually diminishing in rapidity 

 and increasing in breadth, turns suddenly to the east. It 

 almost touches the southern edge of the great Newfound- 

 land bank, where I found the greatest amount of difference 

 between the temperature of the warm water of the Gulf 

 stream, and that of the waters resting on the banks and 

 subjected thereby to a cooling process. Before the stream 



