ations show that the needle was affected by the
rocks; and there will be frequent occasion, in the course of the voyage,
to point out similar anomalies in the observations on land; for they were
found to take place upon almost all those parts of Terra Australis, where
the basis stone is of granite, as here; and also in those where
green-stone, porphyry, basaltes, or iron-stone prevail; whereas in the
lime, or grit-stone countries, the needle did not appear to suffer any
derangement. In the Appendix No. II. to the second volume, where the
changes on ship board, which arose from altering the direction of the
head, are explained, this subject of the differences on shore is
mentioned; for they also were not without a certain degree of regularity.

No set of _Tide_ was perceived on board, either whilst the ship was in
the Sound or in Princess-Royal Harbour; nevertheless it was sometimes
found to run with considerable strength in the narrow entrances of both
harbours. According to lieutenant Flinders' observations on shore during
sixteen days there was only one high water in twenty-four hours, which
always took place between six and twelve at night; for after, by
gradually becoming later, it had been high water at twelve, the next
night it took place soon after six o'clock; and then happened later by
three-quarters of an hour each night as before. The greatest rise
observed was three feet two inches, and the least two feet eight inches.
The accumulation was made in this manner: After low water it rose for
several hours; then ceased, and became stationary, or perhaps fell back a
little. In a few hours it began to rise again; and in about twelve from
the first commencement was high water. It was observed by Captain Cook
upon the east coast of this country*, and since by many others, including
myself, that the night tide rose considerably higher than that of the
day; which is conformable to our observations in King George's Sound; but
with this difference, that in the day we had scarcely any tide at all.

[* See Hawkesworth's Voyages, Vol. III. p. 224.]

The base line for my survey of the Sound was of 2.46 geographic miles,
measured round the curve of the long beach between the two harbours. The
other stations whence bearings were taken with the theodolite were--in
the Sound, four; at the entrance of and within Princess-Royal Harbour,
three; and in Oyster Harbour, four; at each of which a point with a
circle is marked in the pl