In the old , old days , man used to do everything with his own hands. But after a few hundreds of centuries he begin to  make crude instruments out of wood and stone and metal to help him in cutting or breaking or lifting things.A little later , man found out that he could make use of other animals to do these things for him.So he tamed and harnessed many animals to do the heaviest part of his work. Man also discovered that he could use the force of the wind and the current of the stream and of the tides of the sea for propelling his boat or ship. 
 
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