liable to modification by the particular position which the sun occupies in the heavens; or how far the rotatory motion of the earth, combined with the power which the sun possesses of heating certain portions of the circumambient air, are the regulating causes of the Trades, Monsoons, and, indeed, of all the other winds by which we are driven about.  It is by no means an easy problem in meteorology to show how these causes act in every case; and perhaps it is one which will never be so fully solved as to admit of very popular enunciation applicable to all climates.  In the most important and useful class of these aerial currents, called, par excellence, and with so much picturesque truth, “the Trade-winds,” the explanation is not difficult.  But before entering on this curious and copious theme, I feel anxious to carry our convoy fairly across the tropical regions; after which an account of the Trades will be better understood.

I have just mentioned that the changes of temperature, on a voyage to India, are most remarkable.  We set sail, for instance, in the month of March, when it was bitterly cold in England; then we came off the coast of Spain, where it was a little more moderate; next to Madeira, which is always agreeable.  Then we passed the Canaries; after which we sailed over the tropic of Cancer, and got well toasted in the torrid zone; steered down upon the equinoctial line, passed the tropic of Capricorn, and again became conscious of the weakened influence of the sun; till, at length, off the Cape of Good Hope, we were once more nipped with the cold.  Anon, having rounded the south point of Africa, we put our heads towards the line, and a second time, within a few weeks, emerged from the depth of winter into the height of summer.

The proximate cause of all these vicissitudes was, of course, our approach towards and removal from the direct influence of the great source of light and heat.  At one time, the sun, even at noon, was seen creeping stealthily along, low down in the horizon, at another his jolly countenance was blazing away right overhead.  On the 5th of May, when our latitude was 17-1/2 deg.  N., the sun’s declination was 16-1/4 deg.  N., his centre being only one degree from our zenith:  shadows we had none.  On that day we saw St. Antonio, the north-westernmost of the Cape de Verde Islands, the summit of which is about seven thousand feet above the sea.

On the next day I well remember going on deck with a certain flutter of spirits, to see, for the first time in my life, the sun to the northward, and moving through the heavens from right to left, instead of from left to right.  No one doubts that the earth is round; yet these conspicuous and actual proofs of its rotundity always amuse the fancy, and frequently interest the judgment, almost as much as if they were unexpected.  The gradual rise, night after night, of new stars and new constellations, belongs to a still higher order of curiosity; for it not merely