332 HENRY AND THE TELEGRAPH. 



says at tlio end (page 376), he had not been able to add the information received 

 from Oersted, doctor of the University at Copenhagen, about the galvanic labors of 

 scientific men in that country."* 



All that is known of Oersted's simple, generous, and upright character, utterly re- 

 pels any such dark suspicion: and the remarkable interval of eighteen years, which 

 elapsed between the two dates of publication, negatives even the probability of pla- 

 giarism. It seems only wonderful that no other experimental physicist happened to 

 hit upon the observation in all those years. t 



In Sabine's treatise on the "Electric Telegraph," reference is made in a note to 

 Izarn's "Manual of Galvanism" and to his statement of Romagnosi's early discovery :t 

 and in the second edition (of its historical portion), published two years later, Sabine 

 remarks: "The discovery of the power of a galvanic current to deflect a magnet uee- 

 dle, as well as to polarize an unmagnetizcd one, was known to and described as 

 early as 1805 by Professor Izarn in his 'Manuel du Galvanisme.' . . . After ex- 

 plaining the way to iirepare the apparatus, which consists in i>utting a freely suspended 

 magnet needle parallel and close to a straight metallic conductor through which a 

 galvanic current is circulating, he describes the effects in the following words: 'Ac- 

 cording to the observations of Romagn^si, a physicist of Trent, a magnetic needle, being 

 submitted to a galvanic current, undergoes a declination ; and according to those of 

 J. Mojon, a learned chemist of Genoa, unraagnetized needles acquire by this means a 

 kind of magnetic polarity.' To Romagn^si, physicist of Trent, therefore, and not as 

 is generally believed, to Oersted, physicist of Copenhagen, (who first observed in 1820 

 the phenomenon of the deflection of a magnet needle by a voltaic current,) is due the 

 credit of having made this important discovery."^ 



While this is undoubtedly a correct verdict, it remains none the less true that the 

 rapid awakening of European physicists to the significance and importance of the 

 principle of the galvanometer, was due entirely to its rediscovery and reannouucc- 

 ment by Professor Hans Christian Oersted in 1820. 



NOTE C. (From p. 278.) 



ANTICIPATIOXS OF ELECTRO-MAGNETISM. 



From the Treatises on Galvanism, by G. Aldini, published in 1804, and by J. Izarn, 

 published in 1805, (previously noticed,) we learn that Giuseppi Mojon, (.Joseph Moyou 

 In the French,) a chemist of Genoa, on placing steel sewing-needles in connection with 

 a galvanic battery observed that they became magnetic: (probably with transverse 

 polarity.) The description is however very obscure. (Aldini, p. 191; Izarn, p. 120.) 



"It deserves to be remembered," says Dr. Hamel, " that from Aldini's book it was 

 known that the chemist Giuseppi Mojon, at Genoa, had before 1804 observed in un- 

 magnetizcd needles exposed to the galvanic current, ' a sort of polarity'. Izarn repeats 

 this also in his 'Manuel du Galvanisme; ' which book was one of those that by order 

 were to be placed in the library of evei'y Lyc^e in France ".|| 



Still a quarter of a century earlier, in 1777, (now a century ago,) Giovanni Baptista 

 Beccaria, a distinguished Italian natural philosopher, professor of experimental science 

 at Turin, and author of several works on Electricity, in the course of his experiments 



* Journal of the Society of Arts, July 29, 1859, vol. vii, p. 606. 



t " The invention all admired ; and each how he 

 To be the inventor missed ; — so easy seemed 

 Once found, which yet unfound, most would have thought 

 Imijossible." 



(Milton's Par. Lofd, book vi.) 

 X Ihe Electric Telegraph, by Robert Sabine, 8vo, London, 1867, jiart i, chap, iv, se»j. 

 29, p. 22. 



§ History of the Electric Telegraph, 2d edition (in Weale's Rudimentary Treatises), 1869, 

 chap, iv, sec. 27, pp. 23, 24. 



II Journal of the Society of Arts, 1859, vol. vii, j). 606. 



