8 THE OCEAN WORLD. 



truth ; and the importance of making and recording deep- 

 sea soundings is established by the successful immersion 

 of the transatlantic telegraph. 



At the bottom of the Atlantic there exists a remark- 

 able plateau, extending from Cape Eace in Newfoundland, 

 to Cape Clear in Ireland, a distance of over two thousand 

 miles, with a breadth of four hundred and seventy miles : 

 its mean depth along the whole route is estimated at two 

 miles to two miles and a half. It is upon this telegraphic 

 plateau, as it has been called, that the attempt was made 

 to lay down the cable in 1858, and it is on it that the 

 enterprise has been so successfully completed, during the 

 year 1866. Tubular annelids, capable of boring into all IHH | 

 organic substances, are native to this plateau, and have 

 materially assisted in destroying the electric cable. The 

 surface of the plateau had been previously explored by 

 means of Brooke's apparatus, and the bottom was found 

 to be composed chiefly of microscopic calcareous shells 

 (Foraminifera), and a few siliceous shells (Diatomacete). 

 These delicate and fragile shells, which seemed to strew I 

 the bottom of the sea, in beds of great thickness, were 

 brought up by the sounding-rod in a state of perfect 

 preservation, which proves that the water is remarkably 

 quiet in these depths, an inference which is fully borne 

 out by the condition in which the cable of 1858 was UU 

 found, when picked up in 1866. 



The first exploration of this plateau was undertaken by 

 the American brig Dolphin, which took a hundred sound- 

 ings one hundred miles from the coast of Scotland, after- 

 wards taking the direction of the Azores, to the north of 

 which bottom was found, consisting of chalk and yellow 

 sand, at nine thousand six hundred feet. To the south of 

 Newfoundland, the depth was found to be sixteen thousand 

 five hundred feet. In 1856, Lieutenant Berryman, of the 

 American steamer Arctic, completed a line of soundings 

 from St. John, Newfoundland, to Yalentia, off the Irish 

 coast, and in 1857, Lieutenant Dayman, of the English 

 steamship Cyclops, repeated the same operation : this last 



