Page:Physical Geography of the Sea and its Meteorology.djvu/259

Rh one hemisphere and the arrangement of the water in the other; between the rains of the northern and the winds of the southern hemisphere; between the vapour in the air and the salts of the sea; and between climates on opposite sides of the equator. And all this is suggested by merely floating a glass bubble in sea water during a voyage to the Pacific! Thus even the little hydrometer, in its mute way, points the Christian philosopher to the evidences of design in creation. That the arrangements suggested above are adapted to each other, this instrument affords us evidence as clear as that which the telescope and the microscope bear in proof that the eye, in its structure, was adapted to the light of heaven. The universe is the expression of one thought, and that it is so every new fact developed in the progress of our researches is glorious proof.

457. Barometer indications of an open sea.—In the course of our investigations into the physics of the sea, 100,000 observations of the barometer, and more than a million on the direction of the winds have been discussed. They indicate an open water in the Arctic Ocean. They show that about the poles there is a high degree of aërial rarefaction—higher, indeed, than there is about the equator; for the barometer not only stands lower in this place of polar calms than it does in the equatorial calm belt, but the inrushing air comes from a greater distance to the cold than to the warm calms.

458. Polar rarefaction.—The question may be asked, Whence comes the heat that expands and rarefies the atmosphere in these polar places? The answer is, it comes from the condensation of vapour. The south pole is surrounded by water, the north pole by land. But the unexplored regions within the arctic basin are (§ 429) for the most part probably sea, within the antarctic, land. The rarefaction produced in the latter by the latent heat of vapour is such that the mean height of the barometer there is about 28 inches, while that in the arctic calm place is such as to reduce the barometer there to a mean not far from 29.5 inches. In the equatorial calm its mean height is about 29.9 inches. The hypothesis of an open sea in the Arctic Ocean becomes necessary to supply a source for this vapour; for the winds, entering the Arctic Ocean as they do after passing over land and mountain heights of America, Europe, and Asia, must be robbed of much of their moisture ere they reach that ocean; it will require an