3o6 



minutes, — except during the appearance of the Aurora, 

 when they were made every five minutes, and even oftener. 

 The results of these observations were laid down in a chart, 

 which exhibited the intensity of the electric fluid during 

 these twenty-four hours, a period including that of the mag- 

 nificent crimson Aurora, which was observed on the night 

 of the 12th, and morning of the 13th of November, 1838, 

 over every portion of the globe. It appeared, by this 

 chart, that the electric intensity during the existence of this 

 magnificent display of Auroral light was but little above the 

 mean electric intensity of that hour during the month ; from 

 which the author inferred that this phenomenon, if at all 

 electric, occurred at such a distance as to be unable to affect 

 the apparatus. 



The author then proceeded to give an account of the ex- 

 tended series of experiments which he had undertaken at the 

 recommendation of the Academy, and which he had continued 

 during twelve months, at intervals of fifteen minutes, during 

 at least ten days, and from three to seven nights in each month. 

 He stated, that when he had undertaken this series of expe- 

 riments, he had the following objects in view — namely, to 

 determine the mean amount of electric intensity existing in 

 this country, at the different hours of day and night, and 

 the periods of maxima and minima ; and, secondly, to en- 

 deavour to trace the cause of this varying intensity to 

 the influence of some of the recognised agents in nature, — 

 such as the variations of atmospheric pressure ; the vari- 

 ations of temperature ; or the varying quantity of vapour in 

 our atmosphere. 



He was happy to announce, that he had not only deter- 

 mined the mean monthly, and annual force of electricity at 

 the several hours of the day and night, but also had succeeded 

 in establishing its dependence upon two, out of the three 

 agents, with which he had originally proposed to investigate 

 its connexion. The two with which he has established its 



