Another reason why I think that these South-West winds are not caused by the nearness of any large Track of land, is in their being always accompanied with a large swell from the same Quarter, and we find a much greater surf beating upon the Shores of the South-West sides of the Islands situated just within the Limits of the Trade winds than upon any other part of them.
The tides are perhaps as inconsiderable in these Seas as in any part of the world.

A South or South by West moon makes high water in Royal Bay, but the water does not rise upon a perpendicular above 10 or 12 inches, except on some very Extraordinary occasions.
The variation of the Compass I found to be 4 degrees 46 minutes Easterly, this being the mean result of a great number of Trials made by 4 of Dr.
Knight's needles belonging to the Azimuth Compasses, all of which I judged to be good ones, and yet when applied to the Meridian line I found them not only differ one from another sometimes a degree and a half; but the same needle would differ from itself more or less, the difference sometimes amounting to half a degree, both at the same time and on differant days.

This will in a great measure account for the seeming errors that may, upon a nice examination, appear to have been made in observing the Variation inserted in the Course of this Journal.

This variableness in Magnetick Needles I have many times and in many places experienced both ashore and on board of Ships, and I do not remember of ever finding two Needles that would agree exactly together at one and the same time and place, but I have often found the same Needle agree with itself for several Trials made immediately one after another.* (* These discrepancies result from imperfections in the suspension and mounting of the needles, and are only absent in instruments too delicate for ordinary sea service.) However, all this is of no sort of consequence to Navigation, as the Variation of the Compass can always be found to a degree of accuracy more than sufficient for all nautical Purposes.
I have before hinted that these People have an Extensive knowledge of the Islands situated in these Seas.

Tupia, as well as several others, hath given us an account of upwards of 70; but, as the account they have given of their situation is so Vague and uncertain, I shall refer giving a list of them until I have learnt from Tupia the Situation of each island with a little more certainty.