120 OUR PHYSICAL WORLD 



tion was rendered more certain by poling his way across. Boats, 

 or rather rafts, consisting of a few light logs or poles fastened 

 together with thongs or ropes of grass, are still to be found in 

 China, Japan, and other countries where the light bamboo makes 

 ideal material for such craft. One wonders how many centuries 

 it was before the primitive boatmen learned to use the pole as 

 a paddle when they worked out into deep water. Then some 

 inventive genius fashioned a paddle more skilfully, widening its 

 blade, and so contributed to the advance of mankind. Then it 

 is to be presumed some tribes living along shore, instead of 

 trusting to luck to find a suitable log when needed, pulled up the 

 logs, once used, on shore to be used repeatedly. One can 

 readily conceive how some fellow, brighter than the rest, chipped 

 off with his stone hatchet a place to sit, so as to make his log 

 more secure and more comfortable. In time the log was all 

 flattened, for standing on a slippery rounded log is precarious 

 business. Finally the log was dug out so as to hold the fish, the 

 products of the chase, or the boatman's belongings when he 

 went on long expeditions. 



Such dugouts are still widely used and are no mean boats. 

 A huge log is shaped by the patient labor of many workers toiling 

 with crude tools. It may be chipped out or hollowed by fire. 

 Such a craft may hold thirty or forty warriors. These war 

 canoes are used by the people of Africa, South America, Asia, 

 and by the South Sea Islanders. The latter tribes have increased 

 the stability of the canoe by fastening long, light logs out at each 

 side by means of poles. These outriggers prevent the canoe from 

 capsizing and make it quite seaworthy. 



Possibly the next step in advance was taken when it occurred 

 to some early man that he might save labor by fashioning a frame- 

 work of light sticks and covering it with skin or bark, thus 

 avoiding the task of cutting out the hard heartwood of the log. 

 Perhaps such canoes were made first in a region where timber 

 was scarce. At any rate, boats of this type are still familiar, such 

 as the birch-bark canoe of the American Indian, the skin-covered 



