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THE TELEGRAPH ] 
Submarine cables are exposed to many accidents. It would 
at first sight seem, that a cable at the bottom of the sea would 
remain at rest and be subjected to no risk of damage. But this is 
not the case ; for irrespective of the dangers arising from faulty 
a 
Fig. 110. 
construction, the enemies of submarine cables are very 
numerous. 
The destructive agencies may be thus classed : 
Physical causes : —Ice-banks ; friction against rocks ; coral- 
reefs ; earthquakes and submarine disturbances ; elevated 
temperatures on tropical shores. 
Destructive animals : —Teredo, limnoria, xylophaga, sharks, 
saw-fishes, whales. 
Accidental mechanical causes : —Anchors and fishing tackle. 
Physical causes.— Ice-banks : — The Atlantic cables nearest 
the North Pole are evidently more exposed than others to be 
