156 jMr Harris on the Util'dij q/'Jixing 



become deranged to the greatest possible extent. Now, in na- 

 ture, the conditions of such an experiment are found in the re- 

 lative situations of the sea and clouds, and intervening air ; so 

 that when, from any cause, an evolution of natural electricity 

 takes place, and heavy masses of vapour are present in the at- 

 mosphere, we have immediately an insulated conductor (a 

 cloud), directly opposed to a conductor in a free state (the sea 

 or land), and an intervening non-conducting or insulating me- 

 dium, the air ; hence results a charged battery of enormous 

 power : the attraction of the opposite electrical states, therefore, 

 may become at length so powerful, that the electric matter 

 breaks down the intervening resisting air, vvith a terrific and dense 

 explosion — an effect perfectly analogous to the explosion which 

 frequently occurs at the time of conveying a high charge to an 

 electrical battery, and which is attended by a peculiar fracture 

 of the interposed glass *. 



7. The year 1752, which marks an important era in electrical 

 science, from the celebrated discovery of the principle just men- 

 tioned, under the form of the Leyden jar, gave to the natural 

 philosopher an easy method of concentrating large quantities of 

 electricity produced by artificial means, so as to discharge it upon 

 or through bodies with an instantaneous and violent explosion. 

 From the time, therefore, that the cause of lightning became 

 identified with that of ordinary electricity, and that the gigantic 

 attempt of Dr Frankhn and other philosophers, of actually 

 drawing down the matter of lightning from the clouds, was fully 

 accomplished, the effects produced on bodies by these minor 

 electrical discharges with their mode of action, acquired a new 

 interest ; and many important experimental researches into the 

 laws and operation of the great natural action, were successfully 

 carried on by means of the ordinary artificial one. 



8. Amongst the many important results arrived at by such 

 inquiries, are the following : — 



First, In every case of electx'ical explosion, there are univer- 

 sally two points of action, one from which the electric matter 



• An explanation of some of the phenomena of thuntier-stonns on this 

 principle will be found in my printed letter to Sir T. B. Martin, KC.B. 

 Comptroller of his Majesty's Navy. 



4 



