Narrative of the surveying voyages of his majesty's ships Adventure and Beagle (vol.1): between the years 1826 and 1836 : describing their examination of the southern shores of South America, and the Beagles's circumnavigation of the globe

524 GENERAL ItEMARKS. Otaheite. Observer. Date. Variation. Observer. Date. Variation. / I Flinders .. .. 1803 8. 51 E Cook • •• 1769 4. 45 E. Freycinet.. .. 1819 9- 15 E Wales • •• jyys 5. 40 E. Duperrey.. .. 1824 8. 56 E Bayley • •• 1774 5. 49 E. Fitz-Roy.. .. 1836 10. 24 E Vancouver 1794 6. 12 E. Duperrey .. 1823 fi, 40 E. Van Diemen's Land. Fitz-Roy . . .. 1835 7. 34 E. Tasman .. .. 1642 3. 00 E Bay of Islands, N Z 'ealand. Bayley .. .. 1777 Bligh .. .. 1778 7. 29 E 8. 33 E Tasman . . . • 1643 8. 40 E, Fitz-Roy.. .. 1836 11. 06 E Cook . .. 1769 11. 25 E. Duperrey .. 1824 13. 22 E. Mauritius. Fitz-Roy . . .. 1835 14. 00 E. Keeling .. .. 1609 Mathews . . . . 1 722 21. oW 19. 4W. Sydney. Freycinet .. 1818 12. 46 W. Cook . .. 1770 8. 00 E. Duperrey .. 1824 13. 46 w. Hunter . . .. 1787 8. 30 E. 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 tlie situation of the lines of equal variation as a progressive closiiig-in