348 
Mr. Christie's theory of the 
observation, are here, not only sensible, but very commonly 
have a preponderating influence. Such irregularities have 
been occasionally noticed by Canton and Colonel Beaufoy, 
but they are comparatively of extremely rare occurrence; 
and, certainly, irregularities that were not detected by the 
accuracy of Colonel Beaufoy's observations, with a dip of 
70°, would not, simply from the increase of the dip to 88°, 
obliterate every trace of regularity, though they might un- 
doubtedly become sensible. I have made several attempts to 
separate, in these observations, those which appeared to follow 
some general law, from those which appeared to be altoge- 
ther irregular, but hitherto without success, possibly from 
my having been restrained from making any selection that 
might appear to favour the hypothesis I have advanced. 
Perhaps, if the deviations and intensities observed at Port 
Bowen at the several hours throughout the day, were exhi- 
bited as the ordinates of a curve, the times being the abscissae, 
in the manner in which I have represented some observations 
in 1823, the variations and intensities having the true cha- 
racters of maxima and minima might be separated from those 
accidentally the greatest or the least. I have not yet had 
sufficient leisure to accomplish this, but I think that when I 
have, I may be repaid for the time devoted to it, by the light 
that may be thus thrown upon these very interesting ob- 
servations. 
Admitting that the daily changes in the direction of the 
needle may be represented by the revolution of poles near 
the equator, it appears that the times at London, reckoning 
from the passage over the true meridian, of the north pole, 
that of greatest intensity, nearly agree with the times reckoned 
