282 
COMMANDER JOHNSON’S MAGNETIC EXPERIMENTS 
respective magnetic meridians * ; but when the head of the vessel approached to the 
distance of 189 feet towards needle O, and 169 feet from needle D, the “ unmarked 
ends” of both distinctly indicated easterly deviation, and at the distance of 81 feet 
the dipping-needle indicated a decrease of the northern dip. 
As the vessel continued advancing with her head towards the instruments, the de- 
flections of the horizontal needles to the eastward increased, and the northern dip 
decreased ; so that on the near approach of the head the dip had decreased If 0 , and 
the easterly deviation of the horizontal needles amounted to from 5 to 7 degrees. 
The vessel was then swung round, so that her stern was placed as nearly as was 
practicable in the positions that her head had previously occupied, and precisely op- 
posite effects on the several needles were clearly developed ; viz. the unmarked ends 
(or those which pointed to the south) of the horizontal needles were deflected to the 
westward, and the northern dip was increased. 
These experiments were repeated on the following day with similar results as to 
the direction of deflection to those obtained on the 17th of November, the whole of 
which will be found registered in the following Tables. 
* The horizontal needles used in this experiment were suspended on pivots in the usual way, so that it is 
probable a very delicately constructed instrument, with a different suspension, such as is used for determining 
the diurnal variation, would have developed a deflection at a greater distance. 
