of wood. But rain would have extinguished his fire, and he 

 might have accidentally let it go out sometimes. Also, it was 

 diflScult to transfer fire any great distance, so that when 

 Man moved after the animals on which he lived, he would 

 have had to leave his fire behind. Since fire served at least 

 three very important purposes to early Man, viz. for warmth 

 in cold weather, for roasting his meat, and for scaring away 

 fierce animals, it was really essential to find a way to create 

 fire at will. The discovery that rubbing two pieces of wood 

 together could generate a considerable temperature was 

 probably suggested by the similar experiment of rubbing 

 the hands together: next the rubbed woods were shaped 

 so that one was pointed at one end and this end could be 

 placed in a cavity in the other, so that on rapid twisting of 

 the first stick friction at the point raised the temperature 

 locally rapidly, which was helped by the poor thermal con- 

 ductivity of wood. A small amount of inflammable material, 

 e.g. wood slivers, placed in the heated cavity would now 

 ignite when the firemaker blew vigorously onto it. Thus was 

 solved the problem of producing fire artificially, an ex- 

 ample of a primitive experiment. 



The making of shaped stones for various uses began 

 very far in Man's past, even the earliest fossil men known 

 today having had stone tools. Probably the simplest use for 

 a stone to Man was as a hand-held chopper for striking 

 animals: naturally shaped stones were no doubt found at 

 first for this purpose, but few would have had the ideal 

 shape of a sharp front portion with a rounded rear to fit 

 the holding hand. However, the extreme hardness of stones 

 made it appear at first impossible that any method of shap- 

 ing them could be devised. Nevertheless some early men 

 found a deposit of pieces of flint, washed down by a river, 

 and noted that these stones were often broken giving flat 



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