292 COSMOS. 



ology, as well as the geography of plants and animals, has 

 only begun to make actual progress since the mutual depend- 

 ence of the phenomena to be investigated has been fully 

 lecognised. The word climate has certainly special reference 

 to the character of the atmosphere, but this character is itself 

 dependent on the perpetually concurrent influences of the 

 ocean, which is universally and deeply agitated by currents 

 having a totally opposite temperature, and of radiation from 

 the dry land, which varies greatly in form, elevation, colour, and 

 fertility, whether we consider its bare rocky portions or those 

 that are covered with arborescent or herbaceous vegetation. 



In the present condition of the surface of our planet the 

 area of the solid is to that of the fluid parts as 1 : 2-f, (accord- 

 ing to Rigaud, as 100 : 270)*. The islands form scarcely -fa 

 of the continental masses, which are so unequally divided that 

 they consist of three times more land in the northern than in 

 the southern hemisphere; the latter being, therefore, pre- 

 eminently oceanic. From 40 south latitude to the Antarctic 

 Pole the earth is almost entirely covered with water. The 

 fluid element predominates in like manner between the east- 

 ern shores of the old, and the western shores of the new conti- 

 nent, being only interspersed with some few insular groups. 

 The learned hydrographer Fleurieu has very justly named this 

 vast oceanic basin which, under the tropics, extends over 145 

 of longitude, the Great Ocean, in contradistinction to all other 

 seas. The southern and western hemispheres (reckoning the 

 latter from the meridian of Teneriffe) are therefore more rich 

 in water than any other region of the whole earth. 



These are the main points involved in the consideration of 

 the relative quantity of land and sea, a relation which exer- 

 cises so important an influence on the distribution of tempe- 

 rature, the variations in atmospheric pressure, the direction 

 of the winds, and the quantity of moisture contained in the 

 air, with which the development of vegetation is so essentially 

 connected. When we consider that nearly three-fourths of 

 the upper surface of our planet are covered with water ,f we 



* See Transactions of the Cambridge Philosophical Society, vol. vi. 

 pt. 2, 1837, p. 297. Other writers have given the ratio as 100 : 284. 



f In the middle ages, the opinion prevailed, that the sea covered only 

 one-seventh of the surface of the globe, an opinion which Cardinal 

 d'Ailly (Imago Mundi, cap. 8,) founded on the fourth apocryphal book of 



