Meteorological observations and essays / By John Dalton.

  • John Dalton
Date:
1834
Catalogue details

Licence: Public Domain Mark

Credit: Meteorological observations and essays / By John Dalton. Source: Wellcome Collection.

    99/280 (page 73)
    I have never observed any considerable fluctuation of the needle in any evening but when there was an aurora visible, except once ; this was on the 13th of February, 1793, the evening of which was very wet and stormy; the needle varied as follows :—the variation was 24° 57’ at noon; 24° 35’ at 53 P. M.; 24° 35” at 5h 50m; 24° 20’ at 5h 58m; 24° 20’ at Gh; 24°48’ at Gh 20m: 24° 45’ at 6h 45m; 24° 35’ at 8h; 24°47’ at 8h 30m; 24° 49’ at 10h 80m; 24° 53’ at 8 A. M. next day. N. B. There had been an aurora the preceding evening. It should also be noticed, that whilst making these observations upon the disturbance of the needle, during an aurora, I did not always know the absolute variation at the time; and therefore no inferences should be made relative to the change in the absolute variation, in the interval from one aurora to another, from the observations I have given, HND OF THE FIRST PART. L