- n| l/.\ MJMNMI 



have pressed long series of barbarian invaders from At 

 lhl Hun t,. tin- Turkish besiegers of Vienna in 1683. 



Th.- IH a great natural highway to which < 



iron access. In America, 



hawk depression t the northern Appalachian- 



f Canada's from the 



ikes to lli- Hudson. r'nrmerly it enabled the 

 i traders at New AnM.-rdam to tap tin* fu/ trad.- 

 madaV fm the construction of 



the Erie canal, cnahled New York to defy the comp-ti 

 tion of Boston, Philadelphia and Baltimore, in pi 

 ing the easiest outlet for the commerce of the rich ' 

 valley. The ( 'urnlerlan.l Gap was the natural avenue 

 to the West from Virginia and the Carolinas. Buffalo, 

 .n and pioneer liave successively followed this 

 , 14 Natural condition- have fixed channels in which 

 the stream of humanity most easily moves. 85 The din 

 tion of mountain ranges determines within certain limits 

 the destination of migration, and thi- t.-nds to keep suc- 

 ceeding waves to t!:.- old rliaiinel>. These lines of least 

 resistance are first sought out and only when the} 

 Mocked or preempted do the invaders turn to more difti 

 cult paths. 



B long and narrow valley of the Nile, with its fe 

 hem of flood plain on .-hlier hank and the protecting bar- 

 of the great desert beyond furnMied conditions 

 favorable to the development of a gr- 

 lien* was a rich -oil kept in splendid condition 1>\ t 1 8 

 annual flood period which replenished the vital mi 

 and organic uts withdrawn by the crops, so that 



"Scmple, op. til., p. 5. 



8en.pl < mrnron Hittory amd lit Orvgnpkir ComJitio**, p. 68. 



See flgun 53. 



