I 



THE HIGHWAY OF THE WATERS 



of the usual reciprocating type, acting on four propellers 

 for going ahead, and two separate propellers for going 

 astern. These engines develop 68,000 horse-power. 

 Stated in this way these figures convey Httle idea of the 

 power developed. But when we say that it would take 

 a line of horses one hundred and twenty miles long 

 hitched tandem to develop the power generated in the 

 compact space of the Mauretanid's engine room, some 

 idea of the power is gained. 



It is not the matter of power, size, or speed alone 

 that makes the twentieth century passenger steamer 

 so completely outclass her predecessors. It is really 

 the matter of comfort and safety afforded the ocean 

 travelers. Safety against sinking from injury to the 

 hull was provided for by the introduction of water- 

 tight compartments half a century ago, as we have 

 seen; and the size of the Great Eastern has been sur- 

 passed in only a few instances. But it is since the begin- 

 ning of the present century that two revolutionary 

 safety devices have been perfected — wireless telegraphy 

 and the submarine signaling apparatus. The wireless 

 apparatus has been described in another chapter, and 

 as it is used almost as much on land as at sea, cannot 

 be considered as solely a nautical appliance. But 

 the submarine signaling device, which is dependent 

 upon water for transmission, is essentially a nautical 

 mechanism. 



SUBMARINE SIGNALING 



It is difficult for the average landsman to appreciate 

 that the one thing most dreaded by mariners is fog. 



[83] 



