364 PHYSICAL GEOGRAPHY. 



blowing up the English Channel, causes a very perceptible elevation of the sea-level in 

 the Straits of Dover, occasioned by large volumes of water being driven from the 

 Atlantic into the close confinement of a narrow passage. The configuration of that 

 remarkable break in the eastern coast-line of America, where the gulf stream originates, 

 at once explains how a permanent wind and current, pursuing the direction indicated, 

 must heap up the waters of the ocean in it, which necessarily run off, where a rent 

 occurs, in order to find their level. The high temperature of the gulf stream, in all 

 parts of its course, is one of its striking peculiarities. It is a current of warm water, so 

 greatly above the average heat of the ocean, that the navigator may at once detect his 

 entrance into it by the sudden rise of the thermometer. The difference often amounts 

 to 9, 12, and 15 of Fahrenheit, and sometimes to much more. Near Cape Hatteras, 

 on the coast of North Carolina, under the meridian of 63^, the thermometer shows 81 

 in summer, which is from 101 to 11^ above the water of the ocean, in the same lati- 

 tude, immediately contiguous to the stream. At Corvo, one of the Azores, its tempera- 

 ture is from 75J to 72J, which is' from 8 to 10 above that of the ocean. It is in the 

 Mexican Gulf, which may be properly 'called a caldron for heating water, that this high 

 temperature is acquired, which is there in summer 4 above that of the open ocean under 

 the equator. Upon issuing from thence, the water retains its warmth across the At- 

 lantic, though subject to a gradual reduction as it travels eastward, till, after being cooled 

 down to the general temperature of the circumjacent sea, it is transferred again by the 

 westerly current to the coast of Caraccas, to undergo the same heating process as it 

 slowly proceeds along its shores, and those of Mexico and Florida. There can be little 

 doubt, but that as the high temperature of the Mediterranean Sea contributes to the mild 

 climate of the countries on its shores, so the warm water distributed over the North 

 Atlantic, and sent to the west coasts of Europe, causes the mean temperature of England 

 to be sensibly higher than that of many other places situated within the same limits of 

 latitude, but differently circumstanced with reference to the gulf stream. Two physical 

 phenomena, also, off the island of Newfoundland, are supposed to be produced by the 

 action of this current the formation of its bank* and the fogs which mantle its shores. 

 After rushing with great velocity through the strait of Florida, the force of the stream 

 gradually diminishes as it coasts along the United States, when the matter it has sus- 

 tained while in rapid motion is deposited, which in process of time has formed the huge 

 shoals of Nantucket, and the great bank of Newfoundland. In the same locality, the 

 gulf stream encounters the arctic current, and those extraordinary banks of fog with 

 which it abounds, are probably referable to the different temperature of their waters and 

 of the incumbent atmosphere. 



The currents of the ocean materially affect its navigation. While an intimate know- 

 ledge of them is necessary in order to avoid the danger of mistaking the true position of 

 a vessel, its progress to port may be facilitated by falling in with a local stream, or 

 steering clear of it, according as its direction is favourable or adverse. The great high- 

 way across the Atlantic formed by the gulf stream is of course avoided as much as pos- 

 sible by ships proceeding from Europe to America, because the flow of the current is 

 opposite to their path, and to attempt to stem it would increase by a fortnight the time 

 of the passage. On the contrary, a vessel proceeding from North America to Europe, 

 will save about five days' sailing by following its track ; but it has been found, that, 

 owing to its course lying through stormy latitudes, where heavy seas and continual gales 

 are encountered, the damage suffered through wear and tear counterbalances the gain of 

 a few days in the voyage. Accordingly, it is only entered at a few points, a general 

 route to the south of it being pursued by ships coming to Europe from the West Indies, 

 and one to the north by those that sail from New York. As the velocity of the oceanic 



