642 THE INVENTORS OF THE TELEGRAPH AND TELEPHONE. 



.static electricity for telegraphic purposes seems to liave beeu lloiiakls, 

 of Haraniersmith, iu 1810. In this telegraph the letters were printed 

 on ;i disk which was mounted on the seconds arbor of a clock. One of 

 the clocks avus placed at the sending an<l the receiving stations, and 

 arranged to bring corresponding letters simultaneously opposite a small 

 window ill the dial of the clock. When the proper letter was exposed 

 a sigind was sent by means of a pith-ball telegraidi. This telegraph 

 was more complicated than several which have been mentioned above, 

 and re(|uired two clocks going synchronously. 



In the year 1767 an important observation was made by Sulzer. He 

 found that when two plates of different metals were placed one above 

 and the other below the tongue, a peculiar sensation and taste were felt 

 when tlie metals touched each other outside the tongue. Sulzer failed 

 to lind the explanation of this phenomenon, and no further advance 

 was made until the Avell-known frog exijeriments of Galvani gave fresh 

 impetus to the subject. The discoveries of Volta and the invention of 

 the voltaic pile shortly followed. In the same year (1800) an attemiit 

 to close the circuit of a voltaic battery by means of a drop of water led 

 Nicholson and Carlisle to the discovery that water is decomposed by 

 the galvanic current. 



This gave rise to the galvanic or electrolysis telegraphs of Sommer- 

 ing. Coxc, and Sliarpe, and is the basis of all the chemical i)rinting and 

 copying telcgiai)lis which have in more recent times been produced. 

 Siimmering's telegraph was invented in 1809, and was similar in priuci- 

 j)le to that of Morrison, except that the decomposition of Avater and 

 conse(|uent accumulation of gas in a. series of tubes gave the necessary 

 indications. To call attention, it was proposed in connection with the 

 telegraph to liberate an alarm by means (»f an accumulation of gas. 



Prof. Coxe, of Pennsylvania, described a similar telegraph in 1810, 

 and proposed to use either the decomiiosition of water or of metallic 

 salts. Mr. J. E. Sharpe proposed a voltaic telegraph in l.Si;3, and 

 exhibited it before the Lords of the Admiralty, ''who sp(>ke ajiin'ov- 

 ingly of it. but added, that as war was oxer and nioiie\ scarce, they 

 could not carry it into eft'ect. (See liepcrfori/ of Arts, Second Series, 

 vol. XX IX, i>. 1'.").) 



Perhai»s the most iin]>ortant electrical disc(t\er\' in its iiiHuence on 

 telegi'a])hy was made by lloiiiagnesi, of Treiite. in 1S(»5. but received 

 little attention and no develojuneiit niitil it was re-discovered by 

 Oersted in ISIO. This was the diseoNciy that a w ire conveying an 

 electric current is capable of detiectiiig a magnetic needle. In the 



'lowing year Schweigger discoveie<l that the deliecting force was 

 iiHM'cased when he wound the wire several times round the needle. 

 These two discoveries formed the foiindatictn for the construction of the 

 galvaiioscopes and gal\ anoiiieters since so much used in conne<'tioii 

 with electrical api»liaiices and measuiciiieiil s. One of the most exten- 

 sive applications has been to telegraphy^ 



