770 MODIFICATIONS OF ASPECTS OF ORGANIC NATURE 



into account, to be confined within much narrower bounds than 

 some writers are willing to admit. It is possible to overstate the 

 extent to which man can go in the direction of exhausting the 

 soil by wasteful or neglectful agriculture, and to fall over-easily, 

 not to say over-willingly, into despair as to the restoration to 

 fertility and political consideration of countries so mismanaged. 

 And if it is possible to overstate man's influence upon the dry 

 land and its inhabitants, it is necessary to be very cautious as to 

 asserting for him any power of altering, except infinitesimally, 

 the vast area of marine life. Now, as the surface of the sea 

 is to that of the land as four to one, and as I feel somewhat 

 desirous of showing that the extent of the subject I have 

 chosen is not quite so disproportionately large in relation to 

 your time and my abilities as the mere words in which it is 

 announced might seem to indicate, I should like to dwell a little 

 upon this delimitation of it before entering upon the subject 

 itself. 



For one of those striking suggestions ' qui font penser si elles 



excite general interest, it is well to hear Mr. Robert Rawlinson as he spoke in a 

 lecture on Meteorology, delivered November, 1868, before the Royal Engineers at 

 Chatham (p. 7) : — 



'It is certainly true that man modifies climate over tracts that have been cultivated; 

 but it is asserted, further, that in various parts of the world, through cutting down 

 forests, and in consequence of other operations, the works of man, climate %as been so 

 far modified as to have had its character absolutely changed. " The Thames is not 

 now frozen over as in times past," one place has more rain than formerly, another place 

 less, and so on. If by assertions such as these it is intended to be implied that any 

 works of human hands have actually altered the current course of nature, T must meet 

 such allegation with a positive denial. The most stupendous of human works can 

 affect only the comparatively small and narrow space of the earth's surface upon 

 which they may have been executed. Evaporation has only an indirect and inci- 

 dental reference to the land — its real dependence being on the great ocean and the 

 greater sun. And so, while man may exert an influence upon climate over the little 

 area of his operations, his works can avail nothing to affect the grand features of 

 nature even over that small area, or to disturb the majestic scale on which she 

 accomplishes her purposes. Cosmical meteorology is unaffected, and must continue to 

 be unaffected by human agency. The powers of man can never seriously modify the 

 heat of the sun, cloud, rain, or climate, as these have reference to the world at large ; 

 all statements, therefore, which would assign cosmical atmospheric effect to the cutting 

 down of forests, to land drainage, land cultivation and such-like agencies, must be 

 treated with practical disregard.' 



For other discussions on the same subject, see Reclus, 'The Ocean,' sect. ii. pp. 

 93-95, ihique cUata : Unger, as regards Egypt, 'Sitzungsberichte Akad. Wiss. Wien,' 

 xxxviii. pp. 89-93, 1859; De Candolle, 'Hist, des Sciences,' 1873, p. 412; Link, 

 'Urwelt und Alterthum,' ii. pp. 128-160, 1822. 



