APPENDIX. 
On ship -board , .] 
52* 
“ greatest west variations had happened, the ship’s head was North and 
“ Easterly; and that when those, where it was least, had been observed, 
“ it was South and Westerly.” (The greatest west variations in the south- 
ern hemisphere were observed with the head East, on board the Investi- 
gator, and the least with the head West.) “ I mentioned this to captain 
c< Cook, and some of the officers, who did not at first seem to think much 
“ of it; but as opportunities happened, some observations were made 
“ under those circumstances, and very much contributed to confirm my 
c£ suspicions ; and throughout the whole voyage I had great reasons to 
11 believe, that variations observed with a ship’s head in different positions, 
“ and even in different parts of her , will differ very materially from one 
“ another ; and much more trill variations observed on board different 
u ships, which I now find fully verified, on comparing those made on 
“ board the Adventure with my own, made about the same time’’ in the 
Resolution. 
Mr. Wales did not quit the subject here. In the introduction to 
captain Cook’s third voyage, published in 1785, is a paper from the same 
careful observer, citing a variety of cases wherein differences were found 
in the variation of the compass. These cases are as follow. 
1st. Putting the ship’s head a contrary way : differences 3° to 6°, 
and even 10°. 
2nd. At different times of the same day : differences 3° to 7°. 
3d. Being under sail, and at anchor in a road-stead : difference 5*. 
4th. On board different ships : differences 3* to 5°. 
5th. Near the same place, at different times in the voyage : 4° and 
5°, or upwards. 
6th. In different compasses : 3° to 6®. 
That the variation should be different on changing the direction of the 
ship’s head or the place of the compass, and also on board different ships, is 
perfectly reconcileable to the explanation I have given ; but that it should 
vary so much at different times of the same day or year, -when under 
sail and at anchor,— or even in different compasses, much surprised me, 
if all other circumstances were the same. I was therefore induced to ex- 
amine the instances quoted under each case ; and found great reason to 
believe, not only that the direction of the head was changed in most, if 
