Set of four postage stamps issued by China in 1953 showing: (i) Compass of the warring States Era
Set of four postage stamps issued by China in 1953 showing: (i) Compass of the warring States Era, 300BC; (ii) Seismoscope of the East Han Dynasty, 132AD; (iii) Drum cart for measuring distances, Tsin Dynasty, 300AF; (iv) Armillary sphere of the ming Dynasty, 1437AD
