34 Prof. E. Loomis on the c 



of Electrical Currents, 



Aet. lY.^On Electrical currents circulating near the Earth's sur- ^ 

 face, and their connection with the -phenomena of the Aurora Po-' 

 -^am.— 9th Article ; by E lias Loomis, Professor of Natural^ 

 Philosophy and Astronomy in Yale College. 



In vol. xxxii, pp. 324-335 of this Journal, I have shown the 

 existence of a stream of electricity drifting across Central Eu- 

 rope in a direction from about K 28" E. to S. 28° W. For 

 several months I have been collecting the materials for a similar 

 discussion in this country, and now present the results of these 

 enquiries. My materials are derived from the magnetic observa- 

 tions made at Toronto, Cambridge and Philadelphia, from May 

 1840 to Dec. 1842, and during a portion of this time at Wash- 

 ington also. The observations at the first three stations were 

 made with needles mounted in the manner recommended by 

 Gauss ; but those at Washington were made with a declination 

 compass having a needle of eleven inches in length, whose mo- 

 tions were much less free than those of Gauss' construction, and 

 which therefore did not give the time of the maxima and minima 

 with equal precision. For this reason the last column in the 

 following table contains a large number of blanks. The table 

 exhibits a list of all those cases in which there was a well 

 marked maximum or minimum value of the magnetic declina- 

 tion, and when this maximum or minimum value was of short 

 duration. All the dates are expressed in the mean time of 



Toronto. 



jC^SHdie- 



^HHadeJ^ 



-wiiin^o^ 











h! m. . 



1840. May 29. Maximum, 



10 55 



10 55 



10 55 







JIax. 



11 35 



11 25 



11 30 



















mS. 



U 60 



11 35-40 



11 45 







Min. 

 Max. 





12 5-10 









Min. 

























mS 



14 16-20 



14 15 





















m£ 





15 45 









Max. 





15 55 















16 20 







mLx. 

















16 45 





















Min.* 



17 16 

























1? 35 























Max" 



2? S5 



20 30 



20 30-35 





