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On the Course of Electric Currents on the Earth, and on the 

 Cause of Terrestrial Magnetism, By George A. ROWELL, 

 of Oxford.* Communicated by the Author.t 



At the late meeting of the British Association at South- 

 ampton, Professor Oersted, speaking on the deviation of fall- 

 ing bodies from the perpendicular, stated, that experiments 

 on the subject shew that there is a deviation towards the 

 east, which agrees with theoretical calculation; but that there 

 is also a deviation towards the south, which is not easily ac- 

 counted for. In the discussion which followed, it was sug- 

 gested that this phenomenon was caused by currents of elec- 

 tricity, which are said to circulate round the earth in the 

 direction of the parallels of latitude, to which currents are 

 attributed the phenomena of terrestrial magnetism ; but it 

 was considered doubtful whether such currents could cause 

 a falling body to deviate towards the south. 



The phenomenon in question will be more readily accounted 

 for, if it can be shewn that there are currents of electricity 

 in this hemisphere from north to south, the probability of 

 which I endeavoured to prove in a paper read before the Ash- 

 molean Society in 1840, and at the meeting of the British 

 Association at Glasgow. 



As the two theories are, at present, hypothetical, and as 

 both cannot be correct, I will endeavour to shew, that facts 

 preponderate in favour of the latter opinion, and that pheno- 



* Read before the Ashmolean Society, Nov. 23, 1846. 



t I beg respectfully to recall attention to the paper submitted to the Ashmo- 

 lean Society, February 23 (which appears in the Edinburgh New Philosophi- 

 cal Journal for April last), in which I endeavoured to shew the probability 

 that storms and aerial currents are owing to partial vacuums caused by the 

 precipitation of rain, and the escape of electricity from clouds in a much 

 greater degree than to changes of temperature. 



This theory seems, in some measure, confirmed by the extraordinary rains on 

 the European continent during the last month, being accompanied, in England, 

 by violent storms of wind, chiefly from the west and north-west. 



G. A. ROWELL. 



