ran over 50 minutes at the time, which made it the first Soviet animated feature film and one of the first in the world. After that Merkulov, Khodataev and Komissarenko went their own ways. In 1926, Yuri joined Mezhrabpom-Rus and organized an animation department there. Together with Ivanov-Vano he drew animated sequences for Vsevolod Pudovkin's Mechanics of the Brain, the first Soviet popular science movie that received praise from both Ivan Pavlov and international medical specialists. His old friend Daniil Cherkes joined them in their next project — a live-action animated film Senka the African (1927) based on the comedy poem by Korney Chukovsky about a little boy who travelled to Africa on a balloon. It combined hand-drawn and cutout scenes with live action sequences, becoming one of the first Soviet films aimed at children along with The Skating Rink by Yuri Zhelyabuzhsky. Merkulov also directed animated sequences for A Kiss from Mary Pickford comedy movie. In 1928, he launched the first Soviet animated series Bratishkin's Adventures at Mosfilm, this time combining live action with stop motion animation to tell short comedy stories that involved Bratishkin — a tiny sailor who travelled through Moscow taking part in all sort of real-life events. He was joined by the young Alexander Ptushko who helped him creating dolls and sets, and eventually took the director's chair. By that time, Merkulov had already moved to Gosvoenkino (studio dedicated to military documentaries) where he, Leonid Amalrik and Lev Atamanov started an animation workshop. Their most famous project was The First Cavalry (1929) inspired by the 1st Cavalry Army that fought under Semyon Budyonny during the Russian Civil War. Merkulov became obsessed with it back in 1919 when he heard stories by one of the wounded soldiers. Once again the crew combined live action and animation using various techniques. Eduard Tisse conducted the complex cinematography. The film turned a huge success and supported Merkulov's family for several years. He continued working on documentaries and animated agitprop, although by the mid-1930s he started switching to other projects. As an engineer he constructed amusement rides for the Central Park of Culture and Leisure, including a full-size interactive seaplane model equipped with a shooting range. In 1939, he was put in charge of the first exhibition dedicated to the Soviet Navy that took place in the Central Park. He also worked as a conservator-restorer on the Vorontsov Palace in