THE ELECTRIC TELEGRAPH. 



increasing the power of the battery. 106. How the current produces- 

 telegraphic signals. 107. Velocity of the current. 108. Transmission 

 of signals instantaneous. 



87. IT is proposed to connect Europe with the islands of the Medi- 

 terranean and the African continent, by extending the wires which 

 already run continuously to Genoa from the United Kingdom and 

 the Northern States of Europe to Spezzia, and from that point to 

 lay a submarine cable to Corsica, another between Corsica and 

 Sardinia, and another between Sardinia and Bona. The latter 

 place would be connected with Alexandria by underground wires 

 extending along the coast. 



It is even regarded as within the scope of probability that 

 Alexandria may be put in electrical connection with Bombay ; and 

 as the latter place is already connected by a telegraphic line witli 

 Calcutta, a continuous line of communication between London and 

 Calcutta would thus be established. 



The distances between Spezzia and Bona on the coast of Algeria 

 are: 



Miles. 



Spezzia to Corsica (submarine) 76 



Across Corsica (underground) 128 



Corsica to Sardinia by the straits of Bonifacio (submarine) . 7 

 Across Sardinia (underground) . . . . .203 



Sardinia to Bona, on the coast of Algeria, (submarine) about 125 



539 



There would thus be 208 miles of submarine cable in three lengths of 

 76, 7, and 125 miles, and 331 miles of overland wires necessary to con- 

 nect the southern coast of Europe with the northern coast of Africa. 



This is the proposed plan, and the cables from Spezzia to Corsica, 

 and from Corsica to Sardinia are already laid and in operation ; 

 but it will be obvious on inspecting the map that the object would 

 be attainable with a less extent of submarine cable by continuing 

 the overland line to Piombino, in the Grand Duchy of Tuscany, 

 connecting that place with the Island of Elba by a submarine cable 

 of 8 or 10 miles, and connecting the westernmost point of Elba 

 with Bastia, in Corsica, by another cable of 35 to 40 miles. 

 This method would have the further advantage of including in 

 the line several important places on the Italian coast ; such as, 

 Carrara, Massa, Lucca, Pisa, and Leghorn. 



A preference has been given to the course above described in 

 consideration of the benefit conferred upon the company by the 

 concession and guarantee granted by the government of Sardinia, 

 which would not have been given had the other course been followed. 



The cable now deposited contains six conducting wires, and is 

 in all respects similar to that represented in figs. 35, 36. 

 162 



