The enormous island, or continent, as it might almost be called, of Australia, may well be supposed to act the part of a heater from October to April, when the sun is so nearly over it.

During that period the equatorial air is drawn to the south, along the intermediate seas, amongst the Moluccas and other Spice islands, so as to produce a strong and steady north-westerly monsoon.

Of course, the opposite effect will be produced when the sun retreats to the north, and leaves Australia to cool.
These instances are quite enough, I should imagine, to satisfy ordinary curiosity on this point; but professional men ought not to be contented till they have investigated all branches of this important topic; including that elegant and very useful episode, the land and sea breezes of all hot climates, and Horsburgh's East India Directory, which I have quoted above so frequently, is by far the best authority with which I am acquainted on these subjects.

At the same time, I must not omit to do justice to a beautifully-written and accurate Essay on Winds and Currents, by that Prince of all Voyagers, Old Dampier; who, with means far more circumscribed than most of his successors, has contrived to arrange and condense his information in such a way as not only to render it available to practical men, but to make it intelligible and interesting to every class of readers.[4] FOOTNOTES: [3] It is necessary to note here that these questions have been examined since Captain Hall wrote, by Commander Maury, late secretary to the American navy, in the true analytical spirit, and immense progress made in our knowledge of these winds by the mass of practical observations on the subject made by practical navigators, and published under his directions .-- ED.
[4] The principle of "Great Circle Sailing," which now guides the navigator to the Indian Ocean, must be studied in connection with this chapter.

"For every degree the ship changes her longitude south of the Line she sails a shorter distance along the great circle than on any other curve; for on the parallel of 60 deg.