1840.] On Lightning Conductors to Powder Magazines. 281 



yet scarcely a season passes but we hear of accidents within that 

 area, and not unfrequently too in houses actually provided with 

 conductors 



11. I attribute these accidents chiefly to the vertical win- 

 dow rods which constitute all over Calcutta, as in Indian houses 

 generally, a multitude of interrupted conductors, the inducing 

 influence of which is sufficient to counteract much of the bene- 

 fit of the well constructed rods. These vertical window rods 

 are on a large scale, precisely identical with the models contriv- 

 ed by instrument makers to shew at the lecture table the dan- 

 gers of ill- contrived and ill-applied conductors. 



12. Were I called on to protect an isolated house of two 

 stories, with angular edges and roof, containing articles of me- 

 tallic furniture and other good conductors of electricity — under 

 such circumstances I would attach at one angle a common con- 

 ductor several feet higher than the house, in order to divert the 

 lightning the house and its contents could scarcely fail, under 

 many circumstances of exposure, to attract, and at each cardinal 

 point I would place a rod about ten feet high, connected hori- 

 zontally by thick rods and rivets with the main conductor. 



A building so protected I would consider to be as safe as it is 

 practicable to render it, according to the present state of our 

 knowledge. 



13. But in the case of a powder magazine of the ordinary 

 construction, rounded in outline, of trifling elevation, contain- 

 ing no metallic furniture,* removed from other buildings, and not 

 necessarily in the contiguity of conducting objects, I think its 

 chances of being struck by lightning are very little more than 

 those of an equal area of soil or terrace. 



14. We must remember that electric explosions are not 

 chance occurrences, — that they are governed and guided by 

 the influence of S( induction, " the effects of which are now 



* " Fittings" should have been the expression, but the word must now 

 stand unaltered.— W. B. O'S. 



