Page:Physical Geography of the Sea and its Meteorology.djvu/258

232 They are as they were designed to be; and all those agents which are concerned in regulating, controlling, and sustaining them are "ministers of His." Johnston, in the chapter to Plate XV-III. of his great Physical Atlas, thus alludes to the seas, land, and climates of the two hemispheres: "The mild winter of the southern hemisphere, plus the contemporaneous hot summer of the northern hemisphere, necessarily gives a higher sum of temperature than the cool summer of the southern, plus the cold winter of the northern hemisphere. The above-described relations appear to furnish the motive power in the machinery of the general atmosphere of the earth in the periodical conversion of the aqueous vapours into liquid form. In this manner the circuit of the fluid element, the essential support of all vegetable and animal life, no longer appears to depend on mere local coolings, or on the intermixture of atmospheric currents of different temperatures; but the unequal distribution of land and sea in the northern and southern hemispheres supplies an effectual provision, from whence it necessarily follows that the aqueous vapour, which from the autumnal to the vernal equinox is developed to an immense extent over the southern hemisphere, returns to the earth, in the other half of the year, in the form of rain or snow. And thus the wonderful march of the most powerful steam-engine with which we are acquainted, the atmosphere, appears to be permanently regulated. The irregular distribution of physical qualities over the earth's surface is here seen to be a preserving principle for terrestrial life. Professor Dove considers the northern hemisphere as the condenser in this great steam-engine, and the southern hemisphere as its water reservoir; that the quantity of rain which falls in the northern hemisphere is, therefore, considerably greater than that which falls in the southern hemisphere; and that one reason of the high temperature of the northern hemisphere is that the larger quantity of heat which becomes latent in the southern hemisphere in the formation of aqueous vapour is set free in the north in great falls of rain and snow."

456. The results of the marine hydrometer.—In this view of what our little hydrometer has developed or suggested, we trace the principles of compensation and adjustment, the marks of design, the evidence of adaptation between the orbit of the earth and the time from the vernal to the autumnal, and from the autumnal to the vernal equinox; between the arrangement of the land in