52 Mr. Forbes on an Electric Spark Jrom a Natural Magnet. 



I beg to repeat, that the success of Signor Nobili's experi- 

 ment is only known to me through the medium of the public 

 prints ; I am quite ignorant of the channel by which the re- 

 port reached this country ; and, at all events, not the slightest 

 clew has been given as to his mode of arriving at the result. 



Postscript. — Since the preceding paper was read, and placed 

 in the hands of the printer, I have seen the account of the 

 experiments of Signori Nobili and Antinori, contained in the 

 Number of the Annales de Chimie et de Physique, dated Decem- 

 ber 1831* ; and I have likewise, by the kindness of Mr. Fara- 

 day, received a copy of his paper about to be published in the 

 Philosophical Transactions. From these documents, it is esta- 

 blished, 1st, That Mr. Faraday obtained a spark from a tem- 

 porary or electro-magnet, as far back as November 1831. 

 This I stated to have been the case in the preceding paper, 

 upon Mr. Faraday's authority, who informed me of it about 

 two months ago ; and tliis was the " cas particulier" men- 

 tioned in the French version of Mr. Faraday's letter to M. 

 Hatchette, read to the Academy of Sciences, which gave rise 

 to the experiments of Signori Nobili and Antinori, and who 

 also allude to it in their paper, without knowing the real cir- 

 cumstances of the experiment f. It appears, 2ndly, That the 

 first document giving an account of the excitation of a spark 

 by these philosophers, from a permanent or natural magnet:}:, 

 is dated from the Museum at Florence, 3lst of January 1832, 

 was published in the Antologia, bearing the date of November 

 1831, and afterwards translated into the Annales de Chimie^ 

 bearing the date of December. " It is evident," says Mr. 

 Faraday, speaking of the former, " the work could not have 

 been then printed; and though Signor Nobili in his paper has 

 inserted my letter as the text of his experiments, yet the cir- 

 cumstance of the back date has caused many here, who heard 

 of Nobili's experiments by report only, to imagine his results 

 were anterior to, instead of being dependent upon mine§." 



The notice of Signor Nobili's experiment, to which I have 

 alluded in my paper as having reached me whilst my investi- 

 gations were in progress, was that contained in the Literary 

 Gazette for March 24, stating simply the report of the fact, 

 though without naming any authority. I learn from Mr. Fara- 



* A translation of the original paper of Signori Nobili and Antinori, with 

 notes by Mr. Faraday, will be found in the Phil, Mag. and Annals, N. S., 

 vol. xi. p. 401. — Edit. 



t Annales de Chimie, Dec. 1831, pp. 403, 417. 



X See Mr. Faraday's note, Phil. Mag. and Annals, N. S., vol. xi. p. 405. 

 — Edit. 



§ Phil. Trans, for 1832, p. 162, note. 



