294 HENRY AND THE TELEGRAPH. 



magnetic bar — was given. All tliat we had to do therefore was to 

 contrive that this motion shonld be made available for striking bells or 

 for marking indelible dots. This falls within the province of mechan- 

 ics, and there are therefore more ways than one of solving the prob- 

 lem. Hence the alterations that I have made in the telegraph of 

 Ganss, and by which it has assumed its present form, may be said to 

 be founded on my perception and improvement of its imperfections, in 

 harmony with what I had previously laid down as necessary for perfect 

 telegraphic communication. I by no means however look on the arrange- 

 ment I have selected as complete; but as it answers the purpose I had 

 in view, it may be well to abide by it till some simpler arrangement is 

 contrived."* To Steinheil's lasting honor be it said, that when some 

 dozen j^ears later "a simpler arrangement" of the receiving instrument 

 ivas brought to his attention, he was the first to appreciate it and to 

 urge upon the Bavarian Government its adoption, to the abandonment 

 of a portion of his own beautiful system. An example of magnanimity, 

 or more properly of intellectual and unbiased judgment, much rarer 

 with inventors of practical improvements in art, than with discoverers 

 of truth in science. 



These later developments of the telegraph, though in public use at 

 the dates specified, not having been generally described by their authors 

 immediately for publication, were from the meager notices of them found 

 in the foreign journals, but little known in this country for several years 

 afterward; and hence naturally arose the strong patriotic impression 

 with many that the electro-magnetic telegrai)h was essentially an Amer- 

 ican invention. 



About the same time that Steinheil in Munich was engaged in im- 

 proving the needle telegraph, a distinguished chemical philosopher of 

 London, was developing the galvanic battery; and he succeeded in 

 giving that important apparatus a uniformity and continuity of action 

 previously unhoped for. In the adopted forms of the Voltaic battery 

 as arranged by Crnickshanks and others, the oxygen liberated by the 

 active zinc surface rapidly attaclced the plate, forming a coating of oxide 

 over it which soon greatly impaired its chemical and galvanic ef&ciency. 

 On the other hand, the hydrogen liberated at the surface of the copper, 

 remained largely adherent to it in the form of minute bubbles, thus in- 

 sulating it to a corresponding extent from contact with the liquid ; while 

 at the same time dissolved zinc was deposited on its exposed surfiice. 



To obviate these impediments. Professor John Frederic Daniell pro- 

 vided a porous partition between the two metals, which while permitting 

 the necessary conductibility from one side to the other, prevented the 

 convective intermixture of the seiiarated portions of litjuid, and thus 

 also allowed for the first time t"iAO different liquids to be employed for 

 bathing the different metals. The liquid employed on the copper side 



* Stiu'geou's Annals of Electricity, etc. Mar. 1839, vol. iii, iij). 448, 449. 



