From the inside cover:
M. ILIN, who wrote New Russia's Primer and Black on White, is a young Russian engineer, brother of Marschak , the famous Russian poet and story-teller. Both brothers belong to a group of writers who are studying science and history and Soviet life and writing books not only for Russian children but for workers in factories and for peasants. Some of the members of this group are artists, one used to be a cook in the Red Army, two are former homeless children,. All of them work together trying to make simple stories about the real world we live in.
A very fascinating book about the ways time has been measured throughout history.