OCEANS AND SEAS. 



Owing to the peculiar distribution of land and water on the 

 globe, it follows that, strictly speaking, there is but one "great 

 ocean, between all points of which there is a continuous water 

 communication. Nevertheless, geographers have found it con- 

 venient to divide this vast collection of water nominally into 

 several distinct oceans, as will be explained hereafter. 



19. Seas. The term sea is applied to tracts of water one 

 degree inferior in magnitude to the oceans, which are generally 

 limited and enclosed between continents or large islands. 



20. Gulfs are large inlets of the sea partially enclosed by land. 



21. Bays are nearly the same as gulfs, but generally smaller. 

 Like other geographical terms, these however are arbitrary and 

 indefinite, some inlets called bays being greater than others 

 called gulfs. 



Gulfs and bays are the analogues of peninsulas and promontories. 



22. Straits are narrow necks of water connecting tracts of 

 greater extent. A strait is, therefore, the analogue of an isthmus. 



A strait is often but improperly called by the plural term 

 straits ; thus the Strait of Gibraltar is frequently denominated 

 the Straits of Gibraltar. 



23. Channels are narrow tracts of water flowing between 

 opposite coasts that are nearly parallel, and are much wider than 

 straits. 



24. Roads and Roadsteads are tracts of water sheltered by 

 adjacent lands from violent or dangerous winds, having sufficient 

 depth for safety, and not too great depth for anchorage. They are 

 stations where vessels are accustomed to lie at anchor. 



25. Banks and Sandbanks are parts of the bottom which lie 

 so near the surface as to be attended with danger, and in places 

 much affected by tides are often uncovered at low water. 



26. Reefs are sunken rocks, which rise so near the surface, 

 that the waves in passing over them are broken into foam, 

 which thus render their presence manifest to mariners. In a 

 calm sea, however, as there is nothing to indicate their presence, 

 they are a great source of danger to the navigator. 



27. Soundings. The depth of the sea is found by a sounding- 

 line, which is a cord of sufficient length, to the extremity of 

 which a heavy piece of lead is attached. Upon this cord knots 

 are made at intervals of five fathoms, the number of knots counting 

 from the lead being indicated by visible marks. The lead is 

 let down into the sea from the deck of the ship ; the sounding- 

 line to which it is attached being coiled round a cylinder, or 

 reel, which turns freely on an axle. Two seamen hold up the 

 reel by handles at the extremity of the axle, while another 

 observes the line passing over the bulwark of the vessel. The 



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