Studies of periodical processes in the evolution of art became rather widespread. P. Sorokin described cycles of about several centuries; periods close to 50 years have been observed in social relations by S. Maslov; numerous cycles in the stylistic evolution of art became well known due to C. Martindale. One of important characteristics of art history is the ‘intensity of artistic creativity’, which can be measured as the total (summary) volume of encyclopedic descriptions devoted to artists of appropriate creative sphere during every temporal segment of 1..10 years. These rows of ‘experimental data’ form evolutionary curves on historical time interval of several centuries. Such curves contain two components: a long-term trend and an ‘oscillating part’, which have time constants of about decades of years. In the row of historical data, these oscillations may be represented with only 2..10 ‘waves’ including 2 to 10 sampling points pro oscillation period. The goal of investigation is, to measure parameters of such oscillating components.