from a Natural Magnet. 203 



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 December 1831; and I 

 have likewise, by the kindness of Mr FARADAY, received a copy of 

 his paper about to be published in the Philosophical Transactions. 

 From these documents, it is established, 1st, That Mr FARADAY 

 obtained a spark from a temporary 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 this was the " cas particu- 

 lier," mentioned 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 

 circumstances of the experiment *. It appears, 2<%, 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 31st January 1832, was published 

 in the Antologia, bearing the date of November 1831, and after- 

 wards 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 

 Signer NOBILI in his paper has inserted my letter as the text of 

 his experiments, yet the circumstance of the back date has caused 

 many here, who heard of NOBIU'S experiments by report only, 

 to imagine his results were anterior to, instead of being depend- 

 ent upon mine f . 



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

 f Phil. Transactions for 1832, p. 162, note. 



