In 1921 Bertrand Russell delivered two lectures on mathematical logic at Peking University. Manuscripts for the lectures have not been found, but two sets of Chinese notes, which were based on a simultaneous oral translation of Russell's lecturing, were published. The notes are translated into English based on the best readings of both sets. An introduc­tion and notes with a glossary discuss the background and content of the lectures as well as the linguistic difficulties in translating logical terms.