932 Transactions of tue Amekican Institute, 



by electric currents circulating around it, still tlie prime source of 

 all such induction, is undoubtedly to be found in the electro-dynamic 

 and magnetic forces of the sun itself. 



Now the auroral phenomena, being influenced, as we see them, by 

 terrestrial magnetism, it is not difficult to comprehend how any such 

 great disturbances as must be produced in the sun's emanations by 

 the formation of large si:)ots on its surface, may be the occasion of 

 the coincidence mentioned. 



I apprehend that if physicists will hereafter bring their imagina- 

 tions nearer to the earth in their investigations of aurorial displays, 

 and will candidly consider the facts and hypotheses above detailed, 

 they will be able to see that they are inter-atmospheric phenomena, 

 as simple and as easily accounted for as are holes, lightnings, clouds 

 or rainbows. 



Adjourned. 



December 30, 1869. 



Prof. S. D. Tillman in the chair; C. E. Emery, Esq., Secretary. 



The Chairman opened the proceedings by reading the following 

 notes on science. 



Gigantic Electrical Instrument. 

 The largest induction-coil 3^et made is that constructed by Mr. 

 Apps for the Royal Polytechnic Institution of London. It is ten 

 feet long and two feet in diameter. The soft iron core weighs 123 

 pounds ; the primary wire weighs 145 pounds, and is composed of 

 11,310 feet of copper wire. The secondary wire is 150 miles in 

 length. Forty bunsen elements supply electricity for the primary 

 coil. The instrument is capable of producing a spark twenty -nine 

 inches long, and the spark will perforate plate-glass five inches thick. 



Phosphorescence in the Formation of Ozone. 

 Dr. Larrazin has found that pure oxygen gas, reduced by a pres- 

 sure of two millimeters, or even less, becomes luminous under the 

 influence oi electricity. This effect is proved to be due to the 

 formation of ozone from a portion of the oxygen. Any compound 

 gas containing oxygen will also become luminous when exposed to a 

 current of electricity, in the same manner. 



