The steelyard clepsydra,a special type of c lepsydra,had been a chief time-keeping instrument during the Sui-Tang period a nd the earlier stage of Northern Song dynasty.

Lilan Louke-the Important Invention of the Ancient Chinese Timer;

Initiator of Chinese Modern Science——Science Translator Li Shanlan;

Notes on the Famous Qing Mathematician Li Shanlan;

The Research on a Typical Example of Mathematical Education during the Late Qing Dynasty——The Influence of Li Shanlan s Mathematical Work on Yang Zhaojun s Work;