10O 
Mr. Scoresby ,jun. on the anomaly in the 
south pole in north dip ; and the south point being attracted 
jn south dip, where the focus of attraction probably becomes 
a north pole. 
The phenomenon of a ship appearing to lie nearer the 
wind when beating to the northward, with the wind at north, 
than when beating to the southward, with a southerly wind, 
was observed by my father at least 20 years ago, which phe- 
nomenon he attributed to the “ attraction of the ship upon 
the compass;'’ and ever since the year 1805, I have been in 
the habit of allowing only 2 to 2^ points variation on the 
passage outward to Greenland, with a northerly or north- 
easterly course, but generally 3 points variation on the home- 
ward passage when the course steered was S. W. or S. W. 
b. W. Without this difference of allowance, a Greenland ship 
outward bound will be generally found to be to the eastward 
of the reckoning, and homeward bound will be even 4 or 5 
degrees to the eastward of it. 
4. This anomaly in the variation of the compass, occasioned 
by the attraction of the iron in the ship, is liable to change 
with every alteration in the dip of the needle, in the position 
of the compass, or in the direction of the ship’s head. 
If the intensity of the terrestrial magnetism be not equal 
in all parts of the globe, then the anomaly in the variation of 
the compass will be also liable to change with every altera- 
tion in the magnetic influence of the earth. This is a point 
of such importance, I conceive, in the science of magnetism, 
that I was very anxious to procure a dipping needle on my 
last voyage to Greenland, to ascertain whether the mag- 
netism of the earth, by which the dipping needle is influenced, 
be not greater near the magnetic pole, than it is in England* 
