39 o Mr . Christie on the diurnal deviations of the 
It will be remembered that, the effect of an increase of tem- 
perature in the magnets, by diminishing the intensity of their 
forces, is to make both the westerly and easterly points of equi- 
librium approach the north, and that a diminution of temperature 
has the effect of making them both recede from it, independent 
of any other cause. Now, in these last observations, it has 
only happened on one day that I have not seen repeatedly 
both points approach the north when the temperature of the 
magnets has decreased, and both recede from the north with an 
increase of temperature ; showing clearly that the tendencies in 
one case of both points to approach the north, and of both to 
recede from it in the other, were sufficient to counteract the 
contrary tendencies arising from the changes of temperature 
in the magnets ; and proving that the peculiar changes which 
I have noticed, although modified by the temperature of the 
magnets, were not the effects of it. 
I do not propose at present to give these observations, as 
it is my intention to make a series on the precise effects of 
changes of temperature in the magnets, so as to be able to 
free the observations entirely from such effects, by reducing 
them to the same standard. When this is done, I shall no 
doubt find, that the extent of the deviations which I have ob- 
tained require some correction, chiefly in the observations with 
the needle out of the meridian ; and I likewise expect that here 
the times of the maxima deviations will be found nearer to the 
times of the maximum intensity and minimum intensity, as 
determined by Hansteen ; but the leading fact, of the westerly 
and easterly points approaching the north at the same time, and 
receding from it at the same time, during certain periods, will 
remain unaltered. Thus the conclusions which I have before 
drawn respecting the increase and decrease of intensity in the 
