682 



HISTORY OF THE SEA. 



work can be performed. Within this limit, security to life 

 is perfectly compatible with an attempt to recover any ship 

 or sunken treasure which will pay the expenses. 



In Mobile Bay some of the most successful diving opera- 

 tions have been carried on. About a sunken vessel there, 

 it became neoessary to sink a row of piles, into the bed of 

 quicksand which had gathered round her. On trial the 

 ordinary pile-driving machine was found incompetent to do 

 this. Under the strokes of the falling weight the elastic 

 sand rebounded, and the pile was thrown out. This unex- 

 pected difficulty was met in a simple, but most effective way. 

 A sucrinn-pump was rigged up, and the hose tied to the end 

 of a pile ; when the pile touched the bottom the pump w^s 

 set to work, and the suction bored a hole in the sand, into 

 which the pile fell with a rapidity that was startling. When 

 the pile had been sufficiently sunk, the hose was withdrawn, 

 and the sand settling round the pile, held it as fast as though 

 it had been cemented in. 



THE NORTHERN DIVER. 



