524 



GENERAL ItEMAllKS. 



Otaheite. 



Observer, Date, Variation. 



Cook 



Wales 



Bayley 



Vancouver 



Duperrey 



Fitz-Roy 



1769 

 1773 

 1774 

 1794 

 1823 



1835 



4. 45 E. 



5. 40 E. 



5. 49 E. 



6. 12 E. 



6. 40 E. 



7. 34 E. 



Bay of Islands^ N. Zealand. 



Tasman .. .. 1643 8. 40 E. 



Cook .. 1769 11. 25 E. 



Duperrey 1824 13. 22 E. 



Fitz-Roy.. 1835 14. 00 E. 



Sydney. 



Cook 

 Hunter 



1770 

 1787 



00 E. 

 30 E. 



Observer. 



Date. 



Variation. 



Flinders . . 



.. 1803 



0 / 

 8. 51 E. 



Freycinet . . 



.. 1819 



9. 15 E. 



Duperrey . . 



.. 1824 



8. 56 E. 



Fitz-Roy .. 



.. 1836 



10. 24 E. 



Van D 



iemen's Land. 



Tasman , . 



1642 



3. 00 E. 



Bayley . . 



.. 1777 



7. 29 E. 



Bligh 



.. 1778 



8. 33 E. 



Fitz-Roy .. 



.. 1836 



11. 06 E. 



Mauritius. 





Keeling . . 



.. 1609 



21. oW. 



Mathews . . 



.. 1722 



19. 4W. 



Freycinet 



.. 1818 



12. 46 W. 



Duperrey 



1824 



13. 46 W. 



Fitz-Roy.. 



.. 1836 



11. 18W. 



We may derive from the facts in the above table the following 

 general and easily remembered conclusion in regard to the changes 

 of the variation in the southern hemisphere ; namely, that taking for 

 our point of departure the meridian of 65° west in South America, 

 we find that at all the stations east of that meridian to the Cape of 

 Good Hope inclusive, the north pole of the needle has moved 

 towards the west ; and that all the stations west of the same meri- 

 dian to Mauritius inclusive, the north pole of the needle has moved 

 towards the east. 



An almost equally simple generalization may be drawn in respect 

 to the changes of situation of the lines of equal variation in the 

 southern hemisphere : but here it must be supposed either that the 

 reader is thoroughly familiar with the general arrangement of these 

 lines, or that he has a map of them before him. He will find such 

 a map of the variation lines in 1787 in the Fifth Report of the 

 British Association ; but any other map, corresponding to any epoch 

 within the last hundred years, will equally serve the purpose. 

 Referring to such a map, it will be seen that the lines of variation 

 in the South Pacific, form a system of nearly concentric curves, of 

 an oval, or pear-shaped form, the outside curves having a higher 

 variation, which progressively diminishes to the centre. We may 

 regard this system as comprehending the whole of the geographical 

 space between the coast of South America and the meridian of 

 New Zealand. Throughout this space the variation is easterly, and 

 increases : we may consequently characterize the change in the 

 situation of the lines of equal variation as a progressive closing -in 



