277 



Official correspondence on the attaching of Lightning Conductors 

 to Powder Magazines, Communicated by permission of Govern- 

 ment, by W. B. O'Shaughnessy,, Assistant Surgeon, Bengal 

 Medical Service. 



INTRODUCTORY NOTE. 



The great importance and difficulty of the question now under discussion, 

 here and in Europe, regarding the attaching of Lightning Rods to Powder 

 Magazines, led me to solicit the permission of Government for the pub- 

 lication of the following documents. 



Opportunities are so abundant in India for the investigation of such 

 facts as may elucidate the difficulties still besetting this subject, that I 

 should be deficient in all public feeling, did I hesitate in publishing this 

 correspondence, although the high name of Mr. Daniell is arrayed on 

 the opposite side to that which I have taken. 



Mr. Daniell conceives conductors to be at all times infallible in the pro- 

 tection they afford, and he would attach them closely to the Magazine. I 

 adduce facts on the other hand to shew, 1° that to derive perfect safety from 

 this apparatus, we must use many more conductors than are generally 

 directed ; 2° that an inadequate number only increases the risk of a direct 

 stroke of lightning ; 3° that with any number, if placed close to the Maga- 

 zine, although they carry off all the lightning to the ground, the Magazine 

 may still be blown up, by minute sparks occurring among the powder bar- 

 rels, by the disturbance of their own electricity, while the lightning is pass- 

 ing outside the building. 



Mr. Faraday's opinion in all the essential points at issue, coincides with 

 mine ; and my lamented friend, James Prinsep, entertained exactly similar 

 ideas to those advanced in my first report to the Military Board ; in Eng- 

 land, Mr. Sturgeon and Mr. Roberts take the same side in the discussion. 

 Our chief opponents are Messrs. Daniell and Harris, and both these gentle- 

 men, I know not why, have lost temper in the controversy. This indis- 

 cretion I strive to avoid, through respect for my distinguished antagonists 

 and for myself. The question is one simply of facts, and the inferences seem 

 sufficiently obvious ; our sole object is to arrive at the truth, and this can 

 only be reached by the temperate and patient investigation of all the cir- 

 cumstances before us. 



W. B. OS. 



3rd August, 1840. 



