APPENDIX. 813 
No. V.—- A DIAGRAM, 
Shewing the deviation of the compasses on board His Majesty’s ship 
Hecla, at Northfleet, May 6th, 1819. The magnetic dip, or vertical incli- 
nation of the magnetic needle, being 74° 35'. The manner in which the 
experiment was performed, is thus: — the true magnetic bearings of some 
distant object on shore was obtained, which, in this instance, was the steeple 
of a church, bearing E. 6° 30’ N. The inner circle shews the bearings of the 
steeple, with the ship’s head on each of the rhumb-lines, except west, 
Sv <i 
08 
aseu aes NV 
o 
W. by S. and W.S. W.; and the middle circle contains the amount of the 
deviation on those points, which is equal to the difference between the true 
magnetic bearings of the steeple ; and its bearings with the ship’s head on 
the different rhumb-lines marked in the outer circle. 
