Once again about the «landing» of Moscow mathematicians in Petrograd in 1921

The note is devoted to the arrival in June 1921 of a large group of Moscow mathematicians, mainly students of N. N. Luzin, to Petrograd to participate in memorial meetings on the occasion of the 100th anniversary of the birth of P. L. Chebyshev. This historic visit became the first mathematical conference in Soviet history, as well as the first step of Muscovites in overcoming the conflict situation that arose in the 1880s in the relationship between mathematicians of the two capitals.