NO. 8.] PENDULUM OBSERVATIONS. 59 



we obtain for the Observatory in Christiania, 



by the observations in 1892, = 9-81949 m. 

 1893, g = 9-81948 m. 



With the pendulum apparatus belonging to the Norwegian "Gradmaalings 

 Kommission", I have found at the same place, 



in 1892, g = 9'81949 m. 

 1893, g = 9-81952 m. 



These, when regard is paid to the weight of the various values, give as 

 mean for the acceleration in the Christiania Observatory 1 , 



g = 9-81949 m. 



For the calculation of the experiments in which only one pendulum has been 

 employed, I have taken S 3a = 0'5059175 as the value for the period of oscilla- 

 tion of pendulum 33 in the Observatory, assuming S K = 0.5059174 -f 4 X 10 ~ 7 

 to be the period of oscillation at the same place in 1897. The period of oscilla- 

 tion of pendulum 34 will then be S M = 0-5061619. 



The following table gives the result of the calculation. In the column 

 headed 'Calculated Acceleration', are given the values found by the aid of 

 Helmert's formula. 



y fl = 9-780 (1 + 0.005310 sin" q>) m. 



It will be seen that the gravity was found a little too great at the only 

 land-station that was investigated; but the numerical value obtained must, for 

 reasons already given, be considered as only approximate. As regards the 

 other values found for the acceleration, they do not indicate that the gravity 

 over the ocean is greater than on land, when the observations of the 10th 

 and llth June, 1895, are left out of consideration, it having been shown above 

 that they must give too high values. One observation -- that of the 16th 

 January, 1894 - - gives somewhat too low a value, and one that of the 

 16th January, 1896 -- too high a value by not quite so much; otherwise the 

 observed values accord very well with the calculated values. If we now con- 



1 In "Resultate der im Sontmer 1893", etc., p. 8, the following values are given respec- 

 tively for g, instead of those mentioned above: 



and o = 9'81953 I determined with the Fram expedition apparatus; 



g = 9-81950 m. \ determined with the apparatus of the Norwegian "Grad- 

 and = 9'81954 .. / maalings Kommission." 



The reason of this difference has already been given in the note on page 53. 



