In the orthography of his native names he was not so successful. The
constant addition of a redundant "o" has altered many native sounds, such
as Otaheite for Tahiti, Ohwhyhee for Hawaii; while his spelling generally
has been superseded by more simple forms. This is a matter, however, in
which great difficulties are found to the present day by Englishmen,
whose language presents no certain laws for rendering any given sound
into a fixed combination of letters.

Cook's language is unvarnished and plain, as a sailor's should be. His
incidents, though often related with circumstance, are without
exaggeration; indeed if any fault is to be found, it is that he takes
occurrences involving much labour and hardship as such matters of course,
that it is not easy for the reader, especially if he be a landsman, to
realise what they really entail.

Cook was assiduous in obtaining observations to ascertain the Variation
of the compass--i.e., the difference between the direction shown by the
magnetic needle and the true north. He is constantly puzzled by the
discrepancies in these observations made at short intervals. These arose
from the different positions of the ship's head, whereby the iron within
a certain distance of the compass is placed in different positions as
regards the needle working the compass card, the result being that the
needle is attracted from its correct direction in varying degree. This is
known as the Deviation of the compass. The cause of this, and of the laws
which govern it, were only discovered by Captain Flinders in 1805.
Happily for the navigators of those days, little iron entered into the
construction of ships, and the amount of the Deviation was not large,
though enough to cause continual disquiet and wonderment.