and on the Defence of Shipping from Lightning. 181 



only, &c. &c., and " at a distance of fifty feet from the di- 

 rect discharge;" and in sect. 200, lie admits that a discharge 

 from such a jar would " imitate ajiash of lightning striking 

 a similar conductor on the mast." 



Here then is an experiment which at once brings to the 

 bar Mr. Sturgeon's own position ; and I appeal to any one, if 

 what he has thus advanced has any foundation, whether " an 

 electrical accumulation not merely from a jar of a quart ca- 

 pacity, but from twenty-five square feet of coated glass highly 

 charged, and equivalent to destroy fifteen or twenty feet of 

 small iron wire, should not have ignited the powder and 

 caused the mast to be blown in pieces. Yet such was not 

 the case, and never can be so long as the continuous con- 

 ductor remains on its surface. When the exterior conductor, 

 however, was removed and a similar charge thrown on the 

 model, then the mast was blown in pieces, proving, that if the 

 discharge had under any form pervaded the interior, this 

 effect would have resulted in the first case. 



Now Mr. Sturgeon roundly asserts, that " this experiment 

 happens to have no bearing on the subject ivhatever," not- 

 withstanding that in sect. 200 he actually refers to the passing 

 of electricity over conductors placed in given directions, and 

 says, " that the discharge of a jar of only a quart capacity 

 would imitate a flash of lightning striking a similar conductor 

 on the mast :" this is very one-sided reasoning indeed. 



In a subsequent communication he inquires if " I mean to 

 be considered as a philosopher or necromancer by endeavour- 

 ing to persuade the British Association that blowing asunder 

 two pieces of wood by gunpowder was a true representation 

 of the effects of lightning on a ship's mast." 



This may be all very well as the best means Mr. Sturgeon 

 had of parrying the direct bearing of the experiment in ques- 

 tion on his own position ; he must, however, necessarily feel 

 how immediately it involves all the conditions he has himself 

 pointed out as essential to the exhibition of his imaginary re- 

 sults, by which he pretends to have illustrated and proved the 

 effects of lateral discharges of lightning. 



How does it happen, if his views have the slightest 

 foundation, that the heaviest " primitive discharges," to use 

 his own phraseology, can be passed along the exterior con- 

 ductor of the mast without in any way affecting the detonat- 

 ing powder within, even though connected with the interior 

 metals by short metallic nails? it surely should do so, if what 

 he says in sect. 198 be true, viz. "that by this kind of lateral 

 discharge a dense spark may be produced when the bodies are 

 half an inch apart, though the jar be only of a quart capacity 



