Selected Collection
 
southward pointing cart
    This is the direction of the ancient Chinese used to indicate a mechanical device. And the use of the magnetic effect is known for different compass, using the differential gear transmission principle, according to the rotation of the wheels, by the car MuRen directions. No matter the car turned to where, MuRen hand always point to the south. The world famous historian of science and technology, Sinologist praise it Needham as "the world's first adaptive system". About this the earliest record of structure and the principle in the work, and take record ".