Vlll PREFACE TO THE FIEST EDITIOI?'. 



an enlargement of tlie sphere of man's domain, by encroaclmient 

 upon the forests which once covered the greater part of the 

 earth's sm-face otherwise adapted to his occupation. The feUing 

 of the woods has been attended with momentous consequences to 

 the drainage of the soil, to the external configuration of its sur- 

 face, and probably also to local climate ; and the importance of 

 human life as a transforming power is, perhaps, more clearly de- 

 monstrable in the influence man has thus exerted upon super- 

 fi.cial geography than in any other result of his material effort. 



Lands won from the woods must be both drained and irrigated ; 

 river-banks and maritime coasts must be secured by means of ar- 

 tificial bulwarks against inundation by inland and by ocean floods ; 

 and the needs of commerce require the improvement of natural 

 and the construction of artificial channels of navigation. Thus 

 man is compelled to extend over the unstable waters the empire 

 he had already founded upon the solid land. 



The upheaval of the bed of seas and the movements of water 

 and of wind expose vast deposits of sand, which occupy space re- 

 quired for the convenience of man, and often, by the drifting of 

 their particles, overwhelm the fields of human industry with in- 

 vasions as disastrous as the incursions of the ocean. On the other 

 hand, on many coasts, sand-hills both protect the shores from 

 erosion by the waves and currents, and shelter valuable grounds 

 from blasting sea-winds. Man, therefore, must sometimes resist, 

 sometimes promote, the formation and growth of dunes, and sub- 

 ject the barren and flying sands to the same obedience to his will 

 to which he has reduced other forms of terrestrial surface. 



Besides these old and comparatively familiar methods of mate- 

 rial improvement, modem ambition aspires to yet grander achieve- 

 ments in the conquest of physical nature, and projects are medi- 

 tated which quite eclipse the boldest enterprises hitherto imder- 

 taien for the modification of geographical surface. 



The natural character of the various fields where human indus- 

 try has effected revolutions so important, and where the multi- 



