sea on different sides of the line is reconciled by the hypothesis which requires a crossing at the calm belts. The vapour which conveys fresh water and caloric from the southern hemisphere to the northern will in part account for this difference both of specific gravity and temperature, and no other hypothesis will. This hydrometric difference indicates the amount of fresh water which, as vapour in the air, as streams on the land, and as currents in the sea,[1] is constantly in transitu between the two hemispheres. All these facts are inconsistent with the supposition that there is no crossing at the calm belts, and consistent with the hypothesis that there is. It is no argument against the hypothesis that assumes a crossing, to urge our ignorance of any agent with power to conduct the air across the calm belts. It would be as reasonable to deny the red to the rose or the blush to the peach, because we do not comprehend the processes by which the colouring matter is collected and given to the fruit or flower, instead of the wood or leaves of the plant. To assume that the direction of the air is, after it enters the calm belts, left to chance, would be inconsistent with our notions of the attributes of the great Architect. The planets have their orbits, tho stars their course, and the wind "his circuits." And in the construction of our hypotheses, it is pleasant to build them up on the premiss that He can and has contrived all the machinery necessary for guiding every atom of air in the atmosphere through its channels and according to its circuits, as truly and as surely as He has contrived it for holding comets to their courses and binding the stars in their places. These circumstances and others favouring this hypothesis as to these air-crossings, are presented in further detail in Chaps. VII., IX., XII., and XII., also §349.
289. The atmosphere to he studied like any other machinery, by its operations.—In observing the workings and studying the offices of the various parts of the physical machinery which keeps the world in order, we should ever remember that it is all made for its purposes, that it was planned according to design, and arranged so as to make the world as we behold it:—a place for the habitation of man. Upon no other hypothesis can the student expect to gain profitable knowledge concerning the physics of sea, earth, or air. Regarding these elements of the
- ↑ The water which the rivers empty into the North Atlantic has to find its way south with the currents of the sea.
