232 rnYSicAL geography of the sea, and its meteokology. 



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 jiower 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 cur- 

 rents 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 equi- 

 nox is developed to an immense extent over the southern hemi- 

 sphere, 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 Jiemisphere; 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 hemi- 

 sphere 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 



