254 M. A. Quetelet on the state of 



to form a judgement of the respective states of the static and 

 dynamic electricity of the air during the fall of rain which would 

 soon take place. I then quickly reascended. 



Towards 12^* IS"' I recommenced my electric observations, 

 which I continued at intervals of 2 to 3 minutes ; I obtained 

 successively -46°, -57=, -61°, -64°, -65°; during this 

 last observation, the nimbus, which approached more and more, 

 touched the zenith by its nearest edge ; the wind became very 

 sensibly increased, and the first drops of rain commenced to fall ; 

 the electrometer indicated — 69° ; and at the moment when the 

 shower descended —75°, it was 12*^ 33"^; two minutes after- 

 wards the rain fell with less violence, and the electrometer marked 

 — 74°, then —73". At 12'^ 37" the darkest portion of the 

 nimbus had passed the zenith, and the rest of the cloud yieldetl 

 no more water ; but a fresh shower was forming itself to the south 

 and south-east, the electrometer marked 0°; consulted imme- 

 diately afterwards it indicated + 75°. I would have observed the 

 time, but observed with astonishment that my watch had stopped. 



While the rain which set in to the south extended itself to 

 Brussels, but yielding very little water, it continued to develop 

 itself with intensity towards the horizon, while in the mean 

 time new showers were forming to the cast, the north-east, and 

 north. I estimate that the hour was about 12*^ 48'"; the rain- 

 cloud which was in the zenith enlarged itself, and yielded water 

 for a few minutes ; the electrometer continued to be observed 

 and ceased not to indicate -f 75°, the highest degree to which it 

 attained*. 



At a little past 1 o'clock 4he last edge of the cloud touched 

 the zenith ; the sun shone at intervals ; the rain was still very 

 heavy between the S. and E.N.E., the electrometer had not ceased 

 to indicate -1- 75° ; a little after it descended to -(- 72°, the zenith 

 commenced to clear itself; the clouds floated away in different 

 directions ; the wind in the inferior regions was still between 

 the S.W. and the W.S.W. ; and the rain-clouds formed to the 

 S.E. approached ; their edges were strongly indented. 



Towards I*' 10"* I descended and received the observations 

 made by M. Bouvy, who being obliged to leave, had ceded his 

 place to another observer. Here are the indications which he 

 obtained from the galvanometer while I collected those of the 

 electrometer. 



Up to two minutes after the commencement of the rain, the 

 galvanometer had not ceased to preserve its ordinary position of 



* In the course of repairs recently made on the instrument, the scale 

 over which the needle moved was found to be a little contracted. I always 

 remarked, that by the rapidity of the oscillations of the needle I could 

 judge of the moment when the electric tension was a maximum. 



