iiieiit for the theoretical explanation and proof appended to the present 

 notice. 



.ZVo. II. 



Use. Make hm equal in angular value to NH ; then OK, parallel and 

 equal to mL, shows direction of needle and magnitude of horizontal 

 component force on it when correct magnetic north is in direction 

 ON, and ship's head OH: NOH being ship's "magnetic course/' 

 KOH is the corresponding " compass course." 



5. Hale for positions of needles on wmpass card, with dynamical and 

 magnetic reasons. In 1837 a Committee, consisting of Captain Beaufort, 

 Hydrographer to the Admiralty, Captain (Sir J. C. Ross, E-.N., Captain 

 Johnson, E.N., Major Sabine, E.A., and Mr. S. II. Christie, was appointed 

 to remedy defects of the compasses at that time in use in Her Majesty's 

 fleet, and to organize a system of compass management ashore and afloat. 

 The labours of that Committee have conferred signal benefit, not only on 

 the British Xavy, but on the navies and mercantile marine services of all 

 nations in the ' Admiralty Standard Compass,' and in the establishment 

 in 1843 of the British Admiralty Compass Department. The qualities of 

 the magnetic needles and their arrangement on the card occupied much 



