C 's 2 J 
X. Observations on the Dip and Variation of the Magnetic Needle , 
and on the Intensity of the Magnetic Force ; made during the 
late voyage in search of a 'North West Passage. By Captain 
Edward Sabine, of the Royal Regiment of Artillery, F. R. S. 
and F. L. S. 
Read February 25, 1819. 
The dipping needle used in these observations is the property 
of Henry Browne, Esq.; it was made by Messrs. Nairne 
and Blunt, and is similar in construction to one made by the 
same artists, and described by the Hon. Henry Cavendish 
in the 66th volume of the Philosophical Transactions, as used 
in the house of the Royal Society. 
Previously to delivering it into my charge, Mr. Browne 
had adjusted the balance of the needle by means of the screws 
on the cross of wires attached to its axis ; so that no alteration 
took place in the indication of the dip, on reversing the poles. 
The instrument was placed in the direction of the magnetic 
meridian, by a compass stationed at a sufficient distance, and 
suffered to remain during the observations for the purpose of 
occasional verification. When time admitted, the correctness 
of adjustment was also proved, by observing the minimum of 
dip. An equal number of observations were made with the 
face of the instrument towards the east and towards the west; 
the arcs indicated at both ends of the needle were read. 
In determining the intensity of the magnetic force, the 
needle was drawn to an horizontal position by a magnet, and 
being released at an observed moment of time, was suffered 
