One of the earliest designs of perpetual motion machines

Around 1159 A.D.,a mathematician called Bhaskara the Learned sketched a design for a wheel containing curved reservoirs of mercury.He reasoned that as the wheels spun,the mercury would flow to the bottom of each reservoir,leaving one side of the wheel perpetually heavier than the other.The imbalance would keep the wheel turning forever.Bhaskara's drawing was one of the earliest designs for a perpetual motion machine,a device that can do work indefinitely without any external energy source.