Pushball was apparently popular in Germany in, at least, the 1920s and 1930s, and a bit later in the US and England. The rules were somewhat like soccer. There was no weight regulation for the ball so that some were quite heavy and others lighter, as what seems to be the case in this picture. The earliest film of a pushball game is probably in the German silent film, "Ways to Strength and Beauty." -- This card has the number 74, which is the page number onto which one would stick this card in the book, Handbook of Sports. It also mentions page 73, which is where the explanation of the game would be found.