It looks strange that in St Petersburg, which was undoubtedly the main mathematical centre of Russia in the nineteenth and the beginning of the twentieth centuries, a mathematical society was created that late and played, apparently, a nonessential role, being less known than its counterpart in Moscow, for example. However, one should keep in mind that the Academy of Sciences, and most of its members, resided in the then capital [St Petersburg], and essentially performed the functions of a mathematical society, such as conducting scientific meetings, evaluation of papers, awarding prizes etc.It is unclear exactly how long the Society continued to function. In  details of the Society are given covering the time from its foundation until 1900, after which records become poor. It appears that the Society ceased to function around 1905, and certainly by the time of the Russian Revolution in 1917 it had ceased to exit. In March 1918, in the middle of the civil war that followed the Revolution of 1917, St Petersburg stopped being the Russian capital and Moscow took on that role. However, efforts were soon made to restart the St Petersburg Mathematical Society.
Steklov had arrived in St Petersburg in 1906 to take up the Chair of Mathematics at the University. Probably the Society had ceased to exist by the time of his arrival. In 1910 he was elected to the Academy of Sciences then, in 1919, he became vice-president of the Academy. At first he worked to maintain the position of the Academy, then later he put effort into enlarging the activity of the Academy and to reorganising it. He also worked to restart the Mathematical Society, as did A V Vassiliev. They succeed in 1921 when the Society began to function again under the name Petrograd Physical and Mathematical Society (St Petersburg had been renamed Petrograd by this time).
Details of the next phase of the Society's existence is given in the article:
The Petrograd Physico-Mathematical Society.
List of References (4 books/articles)
Other Web site Society Web-site