



by the Mississippi. It falls into the GuLf of Mexico in a very hot 

 region of the earth. There it becomes heated more than before, and 

 along with water from other rivers it starts off on a long journey up 

 the eastern side of IsTorth America, forming a remarkable current 

 called the Gulf Stream. This Gulf Stream is in fact a river in the 

 ocean instead of on land. The warm water that forms it does not 

 mix to any great extent with the cold water which it passes on the 

 way. It flows in a bed of its own over the ocean of colder water. It 

 is quite a shallow river compared with the depth of the ocean beneath 

 it. After continuing its way up to Newfoundland it strikes across 

 the Atlantic. It divides into branches in the middle. One branch 

 passes up to the British Isles and has a remarkable effect on their cli- 

 mate. To understand the effect you must remember two things: 

 First, that the water of the Gulf Stream is much warmer than that of 

 the rest of the ocean around it, and, second, that water when warmed 

 up contains a very great deal of heat, much more than an equal quan- 

 tity of most other substances. To better understand this latter point 

 try the following experiment: Take two bottles exactly alike or two 

 similar tin cans with covers. Fill one with water and the other with 

 anything else, say sand or earth. Then place them in a pot or tin 

 pail and pour water into it until they are nearly covered. Place the 

 whole on the stove and leave it until the water gets too hot for you 

 to put your finger in. Then dip some of the water out of the pot or 

 pail and take the bottles or cans out and put them out in the air to 

 cool. Notice how much more quickly the one containing sand or earth 

 cools than the one containing water. The one containing water has 

 so much more heat that it can not lose it nearly as quickly as the 

 other, and so cools much more slowly. This is the explanation of how 

 the Gulf Stream keeps the land of the British Isles warm in winter, 

 although there is not nearly as much water in the Gulf Stream as 

 there is land in the islands. 



Now, we have only spoken of the Gulf Stream, but there are many 

 other such warm streams in other oceans flowing from the hot parts 

 of the earth to cooler parts and helping to keep these cooler parts 

 warm and fit for habitation. But since warm water is thus spreading 

 from the hot parts of the earth to the cold parts, cold water must flow 

 from the cold parts to the hot parts, and this cold water plays the 

 equally important part of keeping the temperature in the hotter 

 regions lower than it otherwise would be. "Were it not for the moder- 

 ating influences thus received by ocean currents tropical countries 

 near the equator would be too hot for man to live in, and most of 

 Europe and North America would be unbearably cold. 



