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XLIV. On Lightning and Gu?ipoivder Magazines. 

 By Charles Tomlinson, F.R.S., F.C.S., $c* 



SOME time about the year 1845 I visited the Tower of 

 London in company with a relative who was fond of 

 architecture, and wished to inspect the remarkable Norman 

 Chapel of St. John in the White Tower. We were informed 

 that the Chapel was closed, on account of a great bulk of the 

 Public Records being stored in it. The authorities, however, 

 allowed us to view it from an end gallery, which was partly 

 choked up with dusty bundles of paper. We were informed 

 that the vaults below the chapel were used as a gunpowder 

 magazine. At this time the Duke of Wellington was High 

 Constable of the Tower. When some one asked whether he 

 was aware that some of the most valuable historical records 

 of the kingdom were placed over the gunpowder magazine, 

 the Duke replied, " I don't see what harm the Records can do 

 to the gunpowder " I In other words, he was keeper of the 

 gunpowder but not of the Records. 



Nevertheless the danger implied by the question was by no 

 means illusory. In 1767 the Church of St. Nazaire, at Brescia 

 in Lombardy, was struck by lightning, and a quantity of 

 gunpowder belonging to the Republic of Venice, stored in the 

 vaults of the church and estimated at 207,600 lbs. in weight, 

 exploded, when not only the church but a considerable portion 

 of the town was destroyed, and about three thousand persons 

 were killed. When the account of this disaster reached England 

 our Government became alarmed as to the safety of our gun- 

 powder magazines at Purfleet, which were quite unprotected 

 against the attacks of lightning, and the Board of Ordnance 

 sought the advice of the Royal Society as to the best means 

 of protection. The Council appointed a committee, consisting 

 of Dr. Franklin, the Hon. H. Cavendish, Messrs. Watson, 

 Robertson, and Wilson, who inspected the magazines, and 

 found them to consist of five buildings, side by side, each 

 about 150 feet long and 52 feet wide, built of brick and 

 arched under the roof, and standing on a chalk foundation. 

 The Report, which was drawn up by Franklin, recommended 

 an efficient system of pointed metallic conductors for each 

 magazine, terminating at the lower extremity in a well of 

 water to be dug at the end of each magazine. All the mem- 

 bers of the committee signed the report except Wilson, who 

 objected to pointed conductors on the ground that they drew 

 the lightning to the building ; and he recommended blunt or 



* Communicated by the Author. 



