OF MAGNETIC DECLINATION AT GOTTINGEN. 



599 



afternoon preponderates. The mean of all the forenoon fluctua- 

 tions gives 3' 33", that of the afternoon 3' 13". The greatest 

 fluctuation in the last three years, in the forenoon, was on the 

 5th of January, 1838, when the declination was 16' 51" greater 

 than the preceding day; and in the afternoon, on the 12th of 

 July, 1837, when the dechnation was 15' 57" greater than on 

 the 11th. This last is the greatest afternoon fluctuation that 

 has occurred during the six years ; the greatest forenoon fluc- 

 tuation was the one already mentioned in the Resultate for 

 1836, occurring between the 8th and 9th of October, 1835, 

 and amounting to 20' 01". 



From the combination of the forenoon and afternoon fluctua- 

 tions we obtain the following mean values : — 



From the numbers in the last column we cannot yet recog- 

 nize any influence of season on the fluctuations ; longer con- 

 tinued observations will be required to enable us to arrive at a 

 conclusion on this point ; they may also alter materially the 

 mean value (3' 24") of the fluctuations, and still more the mag- 

 nitude of the difference between the forenoon and afternoon 

 fluctuations, supposing the fact of a difference to be confirmed. 



The results drawn from the six years' observations rest on 4323 

 single observations, of which 2164 were made in the forenoon, 

 and 2159 in the afternoon. Of the sixty-one observations 

 which are wanting to correspond with the number of days in 

 the six years, thirty-two were necessarily omitted on account of 



