LAVT3 OF ELECTRIC PHENOMENA. 199 



at Marli : the rod was found capable of giving out electrical sparks 

 when a thunder-cloud passed over the place. This was repeated in 

 various parts of Europe, and Franklin suggested that a communication 

 with the clouds might be formed by means of a kite. By these, and 

 similar means, the electricity of the atmosphere was studied 1>\ 

 Canton in England, Mazeas in France, Beccaria in Italy, and other.-- 

 elsewhere. These essays soon led to a fatal accident, the death of 

 Pdchman at Petersburg, while he was, on Aug. 6th, 1753, observing 

 the electricity collected from an approaching thunder-cloud, by means 

 of a rod which he called an electrical gnomon : a globe of blue fire 

 was seen to leap from the rod to the head of the unfortunate professor, 

 who was thus struck dead. 



['2nd Ed.] [As an important application of the doctrines of eloc 

 tricity, I may mention the contrivances employed to protect ships from 

 the effects of lightning. The use of conductors in such cases is at- 

 tended with peculiar difficulties. In 1*780 the French began to turn 

 fcheir attention to this subject, and Le Roi was sent to Brest and the 

 various sea-ports of France for that purpose. Chains temporarily 

 'applied in the rigging had been previously suggested, but he endea- 

 vored to place, he says, such conductors in ships as might be fixed and 

 durable. He devised certain long linked rods, which led from a point 

 in the mast-head along a part of the rigging, or in divided stages along 

 the masts, and were fixed to plates of metal in the ship's sides com- 

 municatiii"- with the sea. But these were either unable to stand the 



o 



working of the rigging, or otherwise inconvenient, and were finally 

 abandoned. 15 



The conductor commonly used in the English Navy, till recently, 

 consisted of a flexible copper chain, tied, when occasion required, to 

 the mast-head, and reaching down- into the sea ; a contrivance recom- 

 mended by Dr. AVatson in 1 7G2. But notwithstanding this precaution, 

 the shipping suffered greatly from the effects of lightning. 



Mr. Snow Harris (now Sir William Snow Harris), whose electrical 

 labors are noticed above, proposed to the Admiralty, in 1820, a plan 

 which combined the conditions of ship-conductors, so desirable, yet so 

 difficult to secure : namely, that they should be permanently fixed, 

 and sufficiently large, and yet should in no way interfere with the 

 motion of the rigo-ing, or with the sliding masts. The method which 



oo o* o 



he proposed was to make the masts themselves conductors of electricity, 



15 See Le Eoi's Memoir in the Hist. Acad. Sc. for 1790. 



