24 



INTRODUCTION. 



Van Dieman's Land, and Africa, back to the point of starting. It embraces an area of 

 30,000,000 square miles. It is generally covered with floating ice as far north as 60° south 

 latitude, and in higher latitudes appears to be blocked up by an impenetrable barrier of fixed 

 'ce. 



II. The Western Basin forms a channel between the eastern and western continents, and 

 washes their northern sliores. It includes : 



I. The Atlantic Ocean stretching from the Southern Ocean to the Arctic circle ; it is about 

 8,500 miles in length, varying much in breadth, and it covers an area of 25,000,000 square 

 miles ; 



II. The Arctic Ocean surrounding the north pole ; it is in part covered with impenetrable 

 fields of perpetual ice, and it contains large masses of land of unknown extent, it is often 

 called the Icy or Frozen Ocean or Polar Sea ; 



5. Uses of the Ocean. Although it presents to the eye only the image of a watery waste, 

 the ocean sustains an important part in the economy of nature. It is the fountain of those 

 vapors which replenish the rivers and lakes, and dispense fertihty to the soil. By its action on 

 the atmosphere it tempers the extremes of heat and cold. It afibrds an inexhaustible supply 

 of food and of salt, a substance hardly less important. As the great highway of commerce it 

 connects the most distant parts of the globe, affording facilities of intercourse to nations the 

 most remote from each other. 



G. (Seas, Gulfs, and Bays. When the ocean penetrates into the land forming a large ex- 

 panse of water, this inland portion of the ocean is usually termed a sea ; such a body of water 

 of less extent is generally called a guJf or bay ; but these three terms are often confounded. 



The following are the principal bays : Baffin's, Hudson's, James's, Fundy, Passamaquoddy, 

 Machias, Penobscot, Casco, Massachusetts, Buzzard's, Narragansett, Delaware, Chesapeake, 

 Campeachy, Honduras, Bristol, All Saints, Cardigan, Donegal, Galway, Biscay, Bengal, Wal- 

 wich, Fable, False, Angola, Natal, Saldanha, and Botany. 



The following are the principal gulfs ; St. Lawrence, Mexico, Darlen, California, Panama, 

 Guayaquil, St. George, Bothnia, Finland, Riga, Genoa, Naples, Tarento, Venice, Salonica, 

 Persian, Ormus, Siain, Tonquin, Corea, Obi, Guinea. 



The principal seas are the following : Chinese, Carribean, Mediterranean, Okhotsk, Celebes 

 and Corea, Black, North, Red, Baltic, White, Azof, Marmora, and Irish. 



7. Strait, Sound, &c. A narrow passage of water leading from one sea or gulf to another, is 

 called a strait ; a wider passage between two large bodies of water is called a channel or sound. 



The principal channels and straits are the following : Davis's, Hudson's, Belle Isle, Mich- 

 illimackinac, Behring's, Magellan, Skager Rack, Cattegat, Dover, Gibraltar, Bonifacio, Mes- 

 sina, Dardanelles, Constantinople, English, St. George's, North, Babelmandel, Ormus, Mozam- 

 bique, Sunda, Malacca, Endeavor, Bass's, Dampier's, and Cook's. 



The following are the principal sounds : Long Island, Albemarle, Pamhco, Prince Wil- 

 liam's, Queen Charlotte's, and Nootka. 



8. Harbors, Roadsteads, Sic. Small bays or arms of the sea, completely landlocked, or 

 so much so as to protect ships lying in them from the winds and the sea-swell, are called ports, 

 harbors, or havens ; more open arms of the sea, which afford good anchoring ground, are 

 called roads or roadsteads. A good harbor must be deep, capacious, and safe. 



9. Depth of the Ocean. The bottom of the sea appears to have inequalities similar to the 

 surface of the dry land, and the depth of the water is, therefore, various. There are vast 

 spaces where no bottom has been found, and if it is true that the depth of the sea bears any 

 analogy to the elevations of the dry land, it would be in some places from 20,000 to 26,000 

 feet ; the greatest depth ever sounded is 7,200 feet. 



10. Tides. Tides are regular periodical oscillations in the waters of the ocean, which are 

 caused by the attraction of the sun and moon, and which take place twice every twenty-four 

 hours. In the open sea they are at their height three hours after the moon has passed the 

 meridian of the place, and the meridian opposite. Their greatest elevations take place in 

 narrow seas, where the action of the sun and moon is assisted by winds, currents, the position 

 of the coast, &c. The highest tides known are in the Bay of Fundy, where the flood rises to 

 the height of 70 feet. 



11. Currents. Beside the motions produced by the tide, it has been found that there are 

 permanent oceanic currents, always setting in the same direction. There is one called the 

 polar current which sets from each pole towards the equator, as appears from the masses of 



