8 PHYSICAL GEOGRAPHY OF THE SEA, AND ITS METEOROLOGY. 



cliampion in India ; and by the services he thus rendered, entitled 

 himself to the gratitude of all, who with me, take delight in the 

 results which have been obtained. The field which it was proposed 

 to occupy — the firstlings of which were gathered in this little book 

 — was described by him in glowing terms, and with that enthusiasm 

 v/hich never fails to inspire zeal. They are apropos, and it is a 

 pleasure to repeat the substance of them. 



27. " The weight of the atmosphere is equal to that of a solid 

 I'he sea and the at- oflobc 01 lead sixtv milcs in diameter. Its principal 



inosphere contrast- ^-, . ^ t • , • , i i 



ed. elements are oxygen and nitrogen gases, with a vast 



quantity of waiter suspended in them in the shape of vapour, and 

 commingled with these a quantity of carbon in the shape of fixed 

 air, equal to restore from its mass many fold, the coal that now 

 exists in the world. In common with all substances, the ocean and 

 the air are increased in bulk, and, consequently, diminished in 

 weight, by heat ; like all fluids, they are mobile, tending to extend 

 themselves equally in all directions, and to fill up depressions 

 wherever vacant space will admit them ; hence in these respects 

 the resemblance betwixt their movements. Water is not compressible 

 or elastic, and it may be solidified mto ice, or vaporized into 

 steam ; the air is elastic ; it may be condensed to any extent by 

 pressure, or expanded to an indefinite degree of tenuity by pressure 

 being removed from it ; it is not liable to midergo any change in 

 its constitution beyond these, by any of the ordinary influences by 

 vviiich it is affected. 



28. " These facts are few and simple enough ; let us see v;hat 

 Influence of the sun. results aiise from them : As the constant exposure 

 of the equatorial regions of the earth to the sun must necessarily 

 tliere engender a vast amount of heat, and as his absence from 

 the polar regions must in like manner promote an infinite accu- 

 mulation of cold, to fit the entire earth for a habitation to similar 

 races of beings, a constant interchange and communion betwixt 

 the heat of the one, and the cold of the other, must be carried on. 

 The ease and simplicity with which this is effected sm-pass all de- 

 scription. The air, heated near the equator by the overpowering 

 influences of the sun, is expanded and lightened ; it ascends into 

 upper space, leaving a partial vacuum at the surface to be supplied 

 from the regions adjoining. Two cmTents from the poles toward 

 the equator are thus established at the smface, while the sublimated 

 air, diffusing itself by its mobility, flows in the upper regions of 

 space from the equator toward the poles. Two vast whirlpools are 



