XLII. On Atmospheric Electricihj, especially in 1849. 



>/ .1 By J\I. QuETELE-t^jygjjX/, 



''" To Mr. R. TmM'^"''^^, 



My dear Sir, "^^^^^ 



I THINK M. Quetelct's observations so important that I hope 

 you will publish them in the next Number of your Journal, 

 and I doubt not they will have their due effect in indueing many 

 to join the very small band of those who at present observe and 

 study the phsenomena of atmospheric electricity. ''''. " "; ' '""' 



Very truly vour's,"/ ^'^'^^ ^'0]^ 



•^•'lul March IgS^V'''***' tioid'fT itio-ti .anommS 'lo otil rrw;i(T 'jft 



■'"■ My first memoir oli the electricity of the air contained the 

 results of four and a half years' observations. lean now add to 

 them those of 1849, 1850, and the beginning of 18.51 ; you will 

 see them, probably, not without interest. They confirm gene- 

 rally the principal facts deduced from former obsenations j 

 nevertheless the year 1849 has presented a very sensible anomaly 

 during the first seven months: the electricity is then less in a 

 remarkable degree than the or<linary proportion, as you will 

 perceive by the accompanying tables, which, besides the mean 

 and extreme values of each month observed directly, contain 

 also the monthly means obtained in reducing the determinations 

 of each day to the same scale. ■- 



As far as is permitted by the consideration of the years indi- 

 vidually, we meet again with the same law of continuity and the 

 same differences between smnnier and winter as before. 



Nothing is more fitted to make one appreciate the deficiency 

 which still exists in our relative knowledge of the electricity of 

 the air, than the doubt which surrounds the anomalies 1 have 

 observed during the first part of the year 1849. I have been 

 unable to find any observations which may serve to control my 

 own. No obscrvutory, at least a« far as I know, has published 

 up to this time regular daily observations of the electricity of 

 the air; and this constitutes a deficiency most annoying, as wc 

 shall not be long hi perceiving.) )'j> f i!iii>^':|, /!■ ti, ,, ,, ■ 



When a year is remarkable by 'ah abnormal temperature, by 

 extreme rainy or dry jieriods, all meteorologists agree in de- 

 termining its irregularities in the district where they are mani- 

 fested ; unfortunately it is not the same here. I have consulted 

 the most esteemed collections of observations, and I have found 

 nothing there which could satisfy my want. Consequently it 

 may be demanded of me whether the deficiency in the electricity 



* Extraot of ti letter from M. Qiutclct to Mr. rmixUiv, diiteil 2()tli March 

 IH.JI. 



Phil. May. S. J. \'ol. 1. No. I. April 185 J. Z 



