7.8 SEA AND LAND 



again to the ship's deck. In very deep water so slow was 

 the descent of the weight, that it was not easy to tell when 

 it liad attained the ocean-tloor. Moreover, as the ocean 

 waters are often pervaded by currents of considerable veloc- 

 ity which move in various directions, the thick cord in its 

 downgoing would often tlex, now tliis way and now that, 

 and thus give very exaggerated records of the depth at any 



The most important of these difficulties encountered in 

 exploring the depth of the sea, have, through the skill of the 

 American and English explorers of thalassal problems, been 

 overcome. The lead is no longer hung on a roije, but is 

 attached to a hue steel wire, which, because of its tenuity 

 and smootliness, slips easily through tlie water ; the weight is 

 so arranged that when it strikes the bottom it is at once 

 detached from the line, which is then easily wound back 

 to the drum from which it was lowered, while the plummet 

 itself is left to be entombc;d in the strata forming on the sea- 

 lloor. Although these very clever inventions, as well as the 

 com|>licated and beautiful machinery by which tlie miles of 

 delicate wire may be lowered and hoisted in the rolling sea, 

 have made it possible for a properh" ecpiipped exploring ship 

 to determine, in a tolerably accurate manner, the depth of 

 wat(;r at any point, the information which is gained even by 

 very numerous soundings, though valuable, is very meagre. 

 Let us fancy that the atmosphere was as impenetrable to 

 vision as the depths of the ocean, and that creatures which 

 dwelt above it should seek to learn the shape of the land by 

 means of a few thousand soundings disposed in lines here and 

 there, so as to give what we may term sections, over the 

 surface of the terra firma. W'e can easily imagine that 



