The discussions of the Schlick circle most likely reached their zenith, in terms of intensity and number of participants, around 1930, the beginning of its public phase. It was also at this time that the first departures by Feigl (1930) and Carnap (1931) occurred, that Schlick (1931–32) and Menger (1930–31) spent time abroad, and that Menger started his Mathematical Colloquium, a discussion circle that competed to a certain extent with the Schlick circle, and that integrated Gödel into its periphery. Occurring long before 1934, the year of Neurath's emigration and the death of Hahn, these events must count as the first signs of disintegration. At the same time, interest in Wittgenstein decreased (as it had since 1929) and the concern for public effectiveness (through the Ernst Mach Society and international conferences) increased. Both of the latter phenomena contributed to the diffusion of the intellectual centre that had become established in the Boltzmanngasse.