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CHAPTER II.
On each side of the tropic of Capricorn, which we 1839.crossed on the evening of the 19th, we experienced Dec. 19.sharp squalls regularly between 8 a.m. and noon, and sometimes they occurred about 3 a.m. The cumulostratus clouds, of which Sir John Herschel has given so admirable a description, were in all cases the origin of these sudden gusts of wind. The cumuli, like beautiful rolls of wool, were first seen to windward, at the height of 3° 46′, resting upon an ill-defined misty-looking cloud, about one degree high. They formed an irregular arch as they rose; and driven towards us by the wind, we could see the rain falling abundantly. When it had attained 35° of altitude, the squall struck the ship, and compelled us to lower the topsails, and take in all the sails but the foresail. They generally occurred three or four times in the forenoon. During their continuance the wind always veered more to the northward, and they were always preceded by a very perceptible increase of the short sea that obtains in this part of the ocean.
