224* Things not generally Known. 



to such current. Dr. Hamel of St. Petersburg states that 

 Baron Schilling was the first to apply Oersted's discovery to 

 telegraphy ; Ampere had previously suggested it, but his plan 

 was very complicated, and Dr. Hamel maintains that Schil- 

 ling first realised the idea by actually producing an electro- 

 magnetic telegraph simpler in construction than that which 

 Ampere had imagined. In 1836, Professor Muncke of Heidel- 

 berg, who had inspected Schilling's telegraphic apparatus, ex- 

 plained the same to William Fothergill Cooke, who in the 

 following year returned to England, and subsequently, with 

 Professor Wheatstone, laboured simultaneously for the intro- 

 duction of the electro -magnetic telegraph upon the English 

 railways; the first patent for which was taken out in the joint 

 names of these two gentlemen. 



In 1844, Professor Wheatstone, with one of his telegraphs, 

 formed a communication between King's College and the lofty 

 shot-tower on the opposite bank of the Thames : the wire was 

 laid along the parapets of the terrace of Somerset House and 

 Waterloo Bridge, and thence to the top of the tower, about 150 

 feet high, where a telegraph was placed ; the wire then de- 

 scended, and a plate of zinc attached to its extremity was 

 plunged into the mud of the river, whilst a similar plate at- 

 tached to the extremity at the north side was immersed in the 

 water. The circuit was thus completed by the entire breadth 

 of the Thames, and the telegraph acted as well as if the circuit 

 were entirely metallic. 



Shortly after this experiment, Professor Wheatstone and 

 Mr. Cooke laid down the first working electric telegraph on the 

 Great Western Railway, from Paddington to Slough. 



ELECTRIC GIRDLE FOR THE EARTH. 



One of our most profound electricians is reported to have 

 exclaimed: " Give me but an unlimited length of wire, with a 

 small battery, and I will girdle the universe with a sentence in 

 forty minutes." Yet this is no vain boast ; for so rapid is the 

 transition of the electric current along the line of the telegraph 

 wire, that, supposing it were possible to carry the wires eight 

 times round the earth, the transit would occupy but one second 

 of time ! 



CONSUMPTION OF THE ELECTRIC TELEGRAPH. 



It is singular to see how this telegraphic agency is mea- 

 sured by the chemical consumption of zinc and acid. Mr. Jones 

 (who has written a work upon the Electric Telegraphs of Ame- 

 rica) estimates that to work 12,000 miles of telegraph about 

 3000 zinc cups are used to hold the acid : these weigh about 

 9000 Ibs. , and they undergo decomposition by the galvanic 



