CHAPTER I. 



THE MAGNITUDE OF THE SEA. 



Extent of the Ocean. — Length of its Coast-Line. — Mural, Rooky, and .Flat Coasts. 

 — How deep is the Sea f — Average Depth of the Atlantic Ocean. — -The Tele- 

 graphic Plateau between Newfoundland and Ireland. — Measurement of Depth 

 by the Rapidity of the Tide- Wave. — -Progressive Changes in the Limits of the 

 Ocean. — Alluvial Deposits. — Upheaving. — Subsidence. — Does the Level of the 

 Sea remain unchanged, and is it everywhere the same? — Composition and 

 Temperature of Sea-Water. — Its intrinsic Colour. — The Azure Grotto at Capri. 

 — Modification of Colour owing to Animals and Plants. — Submarine Landscapes 

 viewed through the Clear Waters. 



Of all the gods that divide the empire of the earth, Neptune 

 Tides over the widest realms. If a giant-hand were to uproot the 

 Andes and cast them into the sea, they would be engulphed in 

 the abyss, and scarcely raise the general level of the waters. 



The South American Pampas, bounded on the north by 

 tropical palm-trees, and on the south by wintry firs, are no 

 doubt of magnificent dimensions, yet these vast deserts seem 

 Insignificant when compared with the boundless plains of earth- 

 encircling ocean. Nay ! a whole continent, even America or 

 Asia, appears small against the immensity of the sea, which 

 covers with its rolling waves nearly three-fourths of the entire 

 surface of the globe. 



A single glance over the map shows us at once how very un- 

 equally water and land are distributed. In one part we see 

 continents and islands closely grouped together, while in another 

 the sea widely spreads in one unbroken plain ; here vast penin- 

 sulas stretch far away into the domains of ocean, while there 

 immense gulfs plunge deeply into the bosom of the land. At 

 first sight it might appear as if blind chance had presided over 

 this distribution, but a nearer view convinces us that providen- 



