S9® Mr. Christie on the magnetism of 
arising from the rotation of the plate, when its centre and 
plane are in the secondary to the equator and meridian, are 
those best adapted for forming a comparison with the results 
obtained from theory. In Table VI. I have given a series of 
such observed deviations ; but as I was not quite satisfied 
that in making these observations there had not been some 
small inaccuracies in the different adjustments, when the 
centre of the plate was near the equator and when near the 
pole, I should not on this ground have considered a compa- 
rison with them as altogether conclusive with respect to the 
correctness of any theory. In repeating these experiments, I 
increased the distance of the centre of the plate from that of 
the needle, as, in order to simplify the calculations, it would 
be necessary to neglect certain terms, which would be the 
greater the less was this distance, and consequently if it were 
increased, the neglecting these terms would the less affect the 
results of the calculation as compared with the observations. 
The following Table contains a series of observations similar 
to those in Table VI, but having the centre of the plate re- 
moved to the distance i6 inches from the centre of the 
needle. In making them, the most scrupulous attention was 
paid to the different adjustments, so that I can place entire 
confidence in the results. 
