LAWS OF ELECTRIC PHENOMENA. 19 



ing Franklin's conjecture of the analogy of thunder 

 and electricity. This they did by erecting a pointed 

 iron rod, forty feet high, 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 by Canton in England, Mazeas in France, 

 Beccaria in Italy, and others elsewhere. These 

 essays soon led to a fatal accident, the death of 

 Richman 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 (A). 



It is not here necessary to trace the study of 

 atmospheric electricity any further: and we must 

 now endeavour to see how these phenomena and 

 laws of phenomena which we have related, were 

 worked up into consistent theories; for though 

 many experimental observations and measures were 

 made after this time, they were guided by the theory, 

 and may be considered as having rather discharged 

 the office of confirming than of suggesting it. 



We may observe also that we have now de- 

 scribed the period of most extensive activity and 

 interest in electrical researches. These naturally 



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