and on the Effects of Lightning on certain Ships. 417 



the case of the Rodney. But by his admission above-quoted, 

 my method is not objectionable in the top-oallant mast, but 

 is on the contrary calculated to avoid " every sjiecies of dan- 

 ger to the vessel and every chance of danger to the men ;" 

 if so, it must be equally efficient on the top-mast, lower mast, 

 &c. This sort of traverse sailing, to use a nautical phrase, is 

 not a little amusing, and is, I believe, quite unprecedented in 

 any paper on science. 



53. In order that no mistake may arise in respect of what 

 I have advanced relating to lateral explosions, I may in con- 

 clusion simply state, that I do not deny the expansive force of 

 a dense electrical explosion, and its destructive effect on im- 

 yerfect and non-conductors, 1 do not deny its effect in cau- 

 sing expansion in the surrounding air, which I rather choose 

 to call with Priestley, " the lateral force of electrical ex- 

 plosions," than a lateral explosion of electricity. I do not deny 

 this in the absence of any regular system of conductors, or that 

 the discharge may divide in several directions, and in distri- 

 buting itself over the hull, may cause dense sparks and other 

 electrical appearances in various parts of the vessel, but which 

 would not appear, if a perfect system of conduction, such as 

 I have proposed, were resorted to. 



I do however deny the probability of any lateral discharge 

 of electric matter from conducting bodies transmitting an 

 accumulation between oppositely charged surfaces, as as- 

 sumed by sevei'al persons imperfectly acquainted with ordi- 

 nary electrical action, and lately by Mr. Sturgeon; and, I 

 maintain, that neither artificially, nor in the course of nature, 

 can any instance of such lateral explosion be authenticated. 



I am, Gentlemen, yours, &c. 



Plymouth, March 14, 1840. W. Snow Harrjs. 



P.S. It has been insisted on by Mr. Sturgeon, that a shock 

 of lightning, descending a continuous conductor on the mast, 

 would magnetize every chronometer in the cabin, &c. — (Me- 

 moir, Sect. 207.) 



This assumption is completely negatived by the cases above 

 quoted. In fig. 1, an awful discharge descended an iron chain, 

 and yet no magnetic effect was observable on the neighbouring 

 compasses, or on the chronometer in the cabin. It is only in the 

 absence of continuous conductors we find such magnetic effects, 

 and even then their occurrence is comparatively rare. Really, 

 Mr. Sturgeon makes so many random assertions, it is almost 

 impossible to attend to them all. 



