CHAPTER I.
THE MAGNITUDE OF THE SEA.
Extent of the Ocean.--Length of its Coast-Line.--Mural, Rocky, and Flat Coasts.--How deep is the Sea?--Average Depth of the Atlantic Ocean.--The Telegraphic 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 Page 3