OF THE LATE MB. WILLIAM STURGEON. 73 



the electricity induced by it on the earth's, surface. But 

 even were the lateral explosion disproved, it could not be 

 denied that any electrical current must at its rise and fall tend 

 to produce currents of induction, according to the laws dis- 

 covered by Faraday and Henry. Such induced currents 

 must, in the case of a lightning stroke, be excessive, and 

 only estimable by direct experiments on conductors in the 

 neighbourhood of one struck by lightning. It must also be 

 remarked that any discharge will, according to the established 

 laws of conduction of electric currents, distribute itself among 

 all bodies in contact with the lightning conductor, in propor- 

 tion to their conducting powers. The portion thus conveyed 

 might indeed be numerically insignificant as compared with 

 the main stream, but yet sufficient to create sparks, at disrup- 

 tions of such weak conductors, capable of igniting combustible 

 materials. For the above reasons, whatever good fortune may 

 have hitherto attended the conductors at present used in the 

 navy, I cannot but prefer Mr. Sturgeon's system, which re- 

 moves the conductors as far as possible from contact with any 

 portion of the ship or its cargo. 



Atmospheric electricity was a subject to which Mr. Sturgeon 

 devoted a great deal of attention, from the commencement of 

 his scientific career. He was in the habit of raising a kite, 

 the string of which, insulated at the lower end, had a fine 

 wire laid in it. In all seasons and weathers, on high and low 

 ground, in every hour of both day and night, did he pursue 

 this interesting but somewhat hazardous* course of investiga- 

 tion. By the result of more than five hundred kite observations 

 he confirmed the important fact, first discovered by Kinnersley 

 and Beccaria, that the atmosphere in serene weather is uni- 

 formly positive with regard to the earth. He also proved 

 that the higher we ascend the more positive does it become ; 



" See his " Caution to Experimenters with the Electrical Kite," which he 

 published in consequence of having been nearly killed by a discharge from only 

 one hundred yards of wired string, though no thunder was heard. 

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