The water a factor in man's mobility--Oceans and seas the factor of
union in universal history--Origin of navigation--Primitive
forms--Relation of river to marine navigation--Retarded and advanced
navigation--Geographic conditions in Polynesia--Mediterranean versus
Atlantic seamanship--Three geographic stages of maritime
development--Enclosed seas as areas of ethnic and cultural
assimilation--Assimilation facilitated by ethnic kinship--Importance of
zonal and continental location of enclosed seas--Thalassic character of
the Indian Ocean--Limitations of small area in enclosed seas--Successive
maritime periods in history--Contrasted historical rôles of northern and
southern hemispheres--Size of the ocean--Neutrality of the seas--_Mare
clausum and Mare liberum_.


CHAPTER X. MAN'S RELATION TO THE WATER

The protection of a water frontier--Pile villages of ancient
times--Modern pile dwellings--Their geographic
distribution--River-dwellers in old and popular lands--Man's
encroachment upon the sea by reclamation of land--The struggle with the
water--Mound villages in river flood-plains--Social and political gain
by control of the water--A factor in early civilization of arid
lands--The economy of the water--Fisheries--Factors in maritime
expansion--Fisheries as nurseries of seamen--Anthropo-geographic
importance of navigation.


CHAPTER XI. THE ANTHROPO-GEOGRAPHY OF RIVERS