1840.] On Lightning Conductors to Powder Magazines. 289 



at Dum-Dum,* which gave rise to the correspondence., where- 

 as there is no instance upon record of a magazine properly 

 provided with them, suffering injury from the same cause. 



3. In the year 1823 instructions for the erection of light- 

 ning conductors were drawn up, at the instance of the Minister 

 of the Interior of France, by a commission of the Academic 

 Roy ale des Sciences, composed of MM. Poisson, Lefevre, Ginian, 

 Gerard, Dulong, Furet, and Gay Lussac, and adopted by the 

 Academic The Report is published in the 26th vol. of the 

 Annates de Chimie et de Physique. 



4. So lately as the year 1837, the facts relating to thunder 

 and lightning again underwent investigation by M. Arago, who 

 has published in the Annuaire par le Bureau des Longitudes for 

 1838 a very detailed scientific notice " Sur le Tonnerre."f 



5. These two reports have really exhausted the subject, and 

 ought to be sufficient, in my opinion, to convince the most pre- 

 judiced; first, of the impossibility of any extra danger arising 

 from lightning conductors of proper construction ; and, secondly, 

 of the protection which they are competent to afford. 



6. I have lately had the honor of being appointed by the Go- 

 vernment upon a Committee to inquire into the efficacy, and best 

 form of lightning conductors for Her Majesty's Navy, and we 

 have just handed in our report to the Admiralty, in which having 

 collected a great body of evidence upon the subject, and having 

 availed ourselves of the opinions of Doctor Faraday and Profes- 

 sor Wheatstone, we have unanimously recommended the general 

 adoption of Harris's conductors on board Her Majesty's ships. 

 The report has been ordered to be printed for the use of Parlia- 

 ment, and I will take the liberty of transmitting you a copy 

 as soon as it is complete. In the mean time, I will endeavour to 

 reply to some of the observations which Professor O'Shaugh- 

 nessy has made in his report, which is included in the papers 

 referred to me, and upon which, in conjunction with some pri- 



* The building destroyed at Dum-Dum was not a magazine, see the 

 final report, No. 7.— W. B. O'S. 



f Arago's admirable paper had not reached India when I was referred 

 to on this subject.— W. B. O'S. 



