MAN'S DEPENDENCE ON THE EARTH. 105 



precarious existence. Drainage, more and more extensively carried 

 out, and the advance of hygienic science have modified and are still 

 modifying these natural conditions; and Jthe advance of civilization 

 tends to diminish the difference in the specific value of climates to 

 man. 



As to the situation, man formerly, with his limited means, accom- 

 modated himself to Nature in the ways it offered. On the sea, he 

 did not go far from the shores along which he coasted. On the 

 land, he followed the stream, the valley, the mountain gorge, or the 

 cove; and if the mountain stretched out in too compact a mass or 

 presented a too high wall, rather than attack it in front he went 

 round it. It is no longer so. Scientific advance has freed him from 

 his close dependence upon these circumstances. The discovery of 

 the compass brought on the advent of long sea voyages, and made 

 possible the crossing of wide oceans. Moreover, we dig through 

 continents to give passage to ships; attach islands to the mainland 

 by means of gigantic viaducts; and pierce mountains by tunnels to 

 give passage to railways. With each isthmus penetrated, each tun- 

 nel opened, and each new canal and railroad the courses of great 

 commercial currents are turned. The road frequented yesterday 

 is deserted to-day, and solitudes, lately unexplored, are filled with 

 the periodical tumult of railway trains. Countries which were 

 boasting of their situation deplore it now, as shops on a former prin- 

 cipal thoroughfare in cities undergoing transformation are compelled 

 to witness the diversion of movement and life away from them to 

 new streets. 



Thus the rational study of the soil as related to the successive 

 scientific, historical, and social conditions of man gives the key to 

 the local shiftings of civilization through the ages. It rested for 

 a long time on the Mediterranean Sea, the peculiar situation and 

 figure of which facilitated communication between bordering and 

 adjacent countries, and this region was then the whole world, the 

 sailor fancying when he got upon the ocean that he had passed the 

 ends of the earth. The compass was discovered, sailors went farther, 

 even to America, and the Atlantic Ocean became the center of the 

 world; preponderance passed from the southern to the western coun- 

 tries of Europe. The development of steam navigation put all parts 

 of the earth in constant communication. The Isthmus of Suez was 

 pierced, and the Mediterranean recovered part of its lost prestige, 

 while the Southern Atlantic ceased to be the principal route to the 

 East Indies. Other changes, affecting the nations of western Eu- 

 rope, are still going on as results of these events; while in the ex- 

 treme East, China, Japan, the Indies, and Australia, which were 

 hardly known two hundred years ago, are forced into the current 



