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Ball-bearing, The (Author-Bouabdellah)
by Bouabdellah
Date: 27 - Jul - 2008
Level:
intermediate
Age: +12
Description:
Since man began to need to move things, he has used round rollers to make the job easier. Probably the first rollers were sticks or logs, which were a big improvement over dragging things across the ground, but still difficult work.
In 1794, Welsh ironmaster Philip Vaughan invented a device....
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