45 
the intensity of magnetic forces, &c. 
distances from the north, nor is the south point exactly at 
south. In order to reduce the situations of these points to 
their distances from what ought to be considered as their 
meridian, I take the mean of the azimuths of the westerly 
point at the evening observations, which is 8i° 27', and also 
of the corresponding azimuths of the easterly points, 79° 57'; 
half their difference will be the mean error in the point which 
has been considered as zero of the compass with reference to 
these points : so that if 45' be subtracted from each of the 
azimuths of the westerly point, and added to those of the 
easterly, these points will be reduced very nearly to what 
would have been their positions had all the adjustments been 
perfect. With regard to the southerly point of equilibrium, 
the mean of the evening observations gives its position 12' W ; 
this therefore should be subtracted from the westerly and 
added to the easterly, in order to reduce the observed devia- 
tions to those from the meridian. These reductions I have 
made in the following table, preparatory to the reduction to 
be made in consequence of the changes in the temperature 
of the magnets. 
