384 THE OCEAN. 



merchandise between continents isles and nations, 

 the other carries the no less precious, but impond- 

 erable, wealth of messages from land to land. 



The first attempt to lay the cable, in the year 

 1857, was a failure, because the wire parted and 

 the vessel returned with a sorrowful but not dis- 

 heartened company. The next effort was the 

 following year, with a stronger cable aud better 

 machinery for "paying " it out. The cable was 

 seven strands of wire made into a rope and covered 

 with several thicknesses of substances designed to 

 keep the w T ater from reaching the metallic wires 

 which conducted the electricity. When finished it 

 weighed nearly two thousand pounds to the mile 

 in length and was so strong that six miles of it 

 could be drawn straight in water. The number 

 of cables will increase as fast as needed. 



In 1873 there were three in full operation, and 

 they probably will last many years. It requires 

 but a small quantity of electricity to operate them. 



The signals used in ocean telegraphy differ from 

 those used for land lines. On the French line 

 small flashes of light are reflected on a mirror 

 and serve the purpose. The small amount of elec- 

 tricity used on long cables obviates the danger of 

 injury to the wires, by an overcharge. Science 

 has also enabled the electrician, in case of a break 

 in the wire, to tell almost its exact place,to which 

 a vessel can be sent to make repairs. Thus it is 

 that the ocean is subjected to man's dominion day 

 by day. 



THE END. 



