175 
in the position of the horizontal needle , &c. 
left hand , or towards the magnetic meridian ; from whence 
it is inferred, that these contrary effects balance each other 
at S. 85° W. and produce what has hitherto been termed the 
line of minimum daily variation. Nevertheless it is a singular 
coincidence, that the true hearing of this line at Port Bowen 
(viz. S. 38° 4/ E.) agrees nearly with Mr. Barlow’s deter- 
mination at Woolwich. It would, however, be desirable 
to have other observations, at places differing much in mag- 
netic position, before drawing any conclusions as to the 
probability of its dependance on some general cause ; espe- 
cially, since the needle after remaining absolutely stationary 
for three successive days at S. 85° W, commenced moving 
with its north end towards the left hand , or west point of 
the compass, at half-past three P. M. on the 27th of March ; 
without any apparent cause whatever, and that it did not 
again become stationary during the rest of the observations 
at this point, which were continued until the 5th of April ; in 
the course of which, as will be seen, its north end sometimes 
proceeded towards the left, and at others towards the right 
hand, during the time of westerly daily variation. 
Whether this movement of the needle, on the 27th of 
March, took place in consequence of the changes of intensity 
in the opposing magnets ( which were covered with snow), 
arising from the effects of temperature, or from the sud- 
den variations of intensity of the horizontal needle which 
take place in short intervals of time, to which, I am most 
disposed to attribute it, is difficult to decide ; it was not 
considered to be due to the effects of electricity, as there 
was no appearance of the Aurora * at the time, nor was 
* The Aurora generally appeared about north by compass, extending in an arch 
