During the Spring and Autumn period and the Warring States period, we found that the magnet has the properties of absorbing iron and guide. In the 3rd century BC, the ancient book "Han Feizi" recorded Siman (magnet stone guide phenomenon); "The Spring and Autumn Annals of the Lu Dynasty" recorded "kindness (magnetic) stone summons iron", which is perhaps the earliest record of magnetic attraction. In the 2nd century BC, Liu An (179 BC -- 122 BC) wrote a book called "Zhunanzi", which recorded such phenomena as the repulsion of artificial magnets and magnetic poles.

"On Heng" was written by Wang Chong (AD 2797) in the Eastern Han Dynasty. It records the physical knowledge of mechanics, heat, acoustics, magnetism and other aspects. The content is very rich. Wang Chong in "on balance" there is: "the person so speech appeal, air mouth throat, shake the tongue, a shea mouth, so can become a character. Compared with blowing Xiao Sheng, Xiao Sheng is broken. The more the qi is broken, the more the hand has nothing to do, the more it does not sound. The pipe of the husband's flute is swallowed by a Jew's mouth, and the hand is swallowed by a Jew's mouth." He also said: "One's conduct changes the distance between air and fish, and air should change with water."

It can be seen that he has realized that human voice is generated by air vibration, pointed out that the transmission of vibration should be through the medium, and compared the transmission of sound in the air with the transmission of visible water waves. This analogy is still applicable today when we talk about interference and diffraction of sound waves in ultrasonic testing.

Mengxi Pen Talk was written by Shen Kuo (1031 -- 1195), a statesman and scientist in the middle of the Northern Song Dynasty. It is an important work in the history of Chinese science, recording the discovery of geomagnetic declination, imaging principle of concave mirror and resonance phenomena.