I don't have reliable information about a specific artwork titled "Encounter Under the Vault" by Jean Louis Forain in my training data. While Forain (1852 1931) was a French painter, printmaker, and illustrator known for his etchings and social commentary, I cannot provide factual details about this particular work without risking inaccuracy. If you could provide additional context such as the date of creation or the subject matter, I would be better able to assist you.