Popular Science Monthly 



113 



ENGLAND 



Vmllum|iti>n 



m 



OKKNKY 



CAP A 

 FL O W 



ISL4NDS 



The traps are spread from the coast of 

 France clear across the English channel 



would still be so were the grand fleet in the 

 Orkneys to be destroyed. 



When United States Naval officers were 

 consulted concerning the use of these nets, 

 and the possibility of such a method they 

 unanimously agreed that it was possible, 

 although they knew nothing about it. 

 They said that nets were certainly being 

 used and that very probably the minor 

 difficulties in their way had been solved. 



The Latest Salvaging Device for Metals 

 — An Electromagnet 



A LIGHTER acci- 

 dentally turned 

 over at sea, spilling 

 several thousand cases 

 of shells. A diver was 

 put on the job, but 

 owing to the ice and 

 extremely cold water, 

 he was able to work 

 only a few hours at a 

 time. At the end of a 

 day less than one hun- 

 dred cases had been 

 raised. 



An electromagnet was installed and 

 dropped to the river bottom. On the 

 first trip it recovered four cases. This 

 was repeated again and again, until 

 at the end of the day over two 

 hundred boxes had been 

 brought to the surface. 



A large number of 

 cases were broken, so 

 that the shells fell out 

 and sank deep in the 

 mud. This magnet was 

 found powerful enough 

 to draw both shells and 

 cases out of the mud. 



The electromagnet diver bring- 

 ing to the surface cases of shells 

 some of which were buried in mud 



The English fleet, anchored in the Orkney 

 Islands, is completely protected by the nets 



In fact when a shell is left at a distance of 

 about twelve inches from the magnet and 

 the current turned on, the shell, weighing 

 about 255 pounds, jumps to the magnet. 



The outfit consists of a gasoline-driven 

 generator, control apparatus for the mag- 

 net, and the magnet, which weighs about 

 9,000 pounds, and requires from eighty to 

 ninety amperes at 240 volts direct current 

 to energize it. 



The magnet was attached to the cable, 

 and by means of a swinging boom could 

 cover a large area without having to move 

 the lighter on which the apparatus was 

 located. 



In operation, the magnet was 

 lowered to the bottom of the river, 

 a depth of between thirty and forty 

 feet; then the current was turned 

 on and the magnet lifted. Then the 

 boom swung the magnet over to the 

 deck, the current was switched off, 

 and the cases of shells 

 were dropped. 



This type of magnet 

 (designed for handling 

 scrap iron and steel) 

 though never intended 

 to operate under water, 

 is quickly attached and 

 in this particular case 

 was operated with marked 

 success for ten consecutive 

 days with no special at- 

 tention or repairs except 

 perfunctory tightening of 

 the bolts and filling the 

 main feed cables with tar. 

 The cases of shells were 

 recovered with compara- 

 tive ease. The method will 

 probably be used for other 

 salvaging purposes. 



