748 



THE AURORA BOREALIS. 





Hour. 



Charge from 



Temp. 





Date. 



Air. 



Ground. 



Bat- 

 tery. 



Remarks. 



Mar.2i 

 » 25 



,. 25 



h. 

 16. 



10 

 15 



- 9 

 C + 20~) 

 S +18 ^ 

 L + 25) 



I +35 j 



-28 

 -48 



-36 



6 to 7 

 10-5 



-°28 

 -33 



-31 



Clear and calm. 



r Charge from air suddenly became —32, 



< probably the ball was touched by one 



C of the stays. 



("Charge from battery disappeared quickly. 



I Clear. Light E. wind. 



Light S.S.E. wind. Clouds gather and 

 temperature is raised during the night 

 from -34° to -15°. 



Cloudy and calm. 



Charge from battery immediately dis- 

 appeared. 



Wind N., with snow. Charge disappeared 

 instantly. 



With lamp rapidly raised. Rain mixed 

 with snow. Wind W. 



„ 25 



„ 26 

 .. 26 



21 



10 

 15 



+ 25 

 -15 



-30 

 -12 



8 to 9 



-34 



- 7 



- 5 



» 27 



10 



+ 2 



-0-5 



3 to 4 



-17 



„ 27 



22 



+ 1 



- 



- 



-24 



» 28 



10 



r-t 



-23) 



-24J 



6 to 7 



-18 



Cloud and calm. 



» 28 

 „ 30-31 



15 



- 2 



- 3 



5 to 6 



_ 



-10 



-17 

 to -13 



The air once gave +1*5. A little snow. 



Wind S.E. 

 Several experiments. Charge instantly 



disappeared. 



A few more successful experiments were made until May 24, 

 but the charges instantly disaj)peared, although the insulation of 

 the instrument apj)eared to be as good as ever. 



Observations repeated as spring came on, when the temperature 

 approached zero showed the same results as in the autumn. 



There was great difficulty in keeping the electrometer in a good 

 state. The walls of the room allowed the wind and snow to 

 penetrate, and occasionally the instruments were buried in snow, 

 and the room torn with the violent storms. 



The obsen'-ations agree in showing that the air conducts elec- 

 tricity very easily at relatively high temperatures, and to this is 

 due the absence of thunder and the existence of the Aurora. 



This is said to be due to the 7noisture in the air in those 

 regions, but the same temperature and the same degree of mois- 

 ture do not produce this effect in lower latitudes. At the lower 

 temperatures —20°, — 30°, and still lower, the air insulates better. 

 Generally the air is electrified positively and the ground nega- 

 tively. On several occasions the air could only be regarded as 

 itself holding a charge, and not as charged by induction from the 

 Earth. 



At certain periods of spring, when the air insulated pretty well, 

 the ground and the air were both charged with negative electricity. 

 A change in the electricity of the air was not a constant result 

 of greater cold, but when the temperature had been low for some 

 time the air seemed to have a tendency to be electrified negatively. 



It seems that there is a very natural relation between these 

 facts and the Aurora, as far as conclusions may be drawn from so 

 few observations. 



In the months of January and February Auroras were constantly 



