AND LTGHTNINQ CONDUCTORS. 



7$ 



and consequently that the yard-arm was struck by a por- 

 tion only of the whole force, there is much reason to dread 

 the effects of a full and complete oblique discharge of light- 

 ning amongst the rigging of a vessel on which it falls. 



40. Another case of oblique discharge occurred to 

 H. M. ship Fisguard, 42 guns, September 29, 1846, whilst 

 at anchor at the mouth of the Nisqually river, in the Oregon 

 territory. In this case the lightning struck the main-mast 

 only a few feet above deck. This ship was furnished with 

 a conductor in each mast at the time. The indications of 

 this oblique discharge were ruptures in the conductor, and 

 its being started from the mast ; all of which occurred within 

 13 feet above deck. The places at which the conductor 

 was started from the mast, were respectively at "twelve 

 and a half, seven and a halfj and two and a half feet above 

 the upper deck. The plates of copper forming the conduc- 

 tor were separated at the lowest point, and thrust, as it were, 

 asunder : the edge of the groove in which the plates were 

 laid, was slightly rent by the starting of the plates, thereby 

 causing two or three splinters to fall on the deck at the time 

 of the discharge." * It is also stated that the mast was 

 " slightly singed " at the lower mast point, or where the cop- 

 per plates were separated ; hence there is reason to infer 

 that this was the principal point on which the lightning 

 btruck the mast; and the probability of this being in reality 

 that which actually took place, is strongly supported by the 

 fact, " that several boarding-pikes ranged round the main- 

 mast were displaced, and their wooden stand slightly char- 



redJ't 



41. The track of the lightning in this case (40), would be 

 within the height of an ordinary sized man before it arrived 

 at the mast ; hence the probability of a great sacrifice of 

 life had men been standing on the same side of the mast at 



* Harris's " Remarkable Examples," &c. 

 t Ibid. (Captain Duntze's Official Report.) 



