The case of Avery v. Popper in 1900 revolved around a dispute over land ownership and the interpretation of certain laws related to it. The plaintiff, Avery, claimed that he had purchased a piece of property from the defendant, Popper, but later discovered that there were existing liens on it which hadn't been disclosed at the time of purchase. He argued this constituted fraud and sought damages for his losses as well as cancellation of the sale contract. However, Popper contended that he was not aware of these liens when selling the property and therefore could not be held liable for them. The Supreme Court ruled in favor of Avery stating that ignorance is no excuse under law; if someone sells a property without disclosing all relevant information about its status (including any existing liens), they can be held responsible for any resulting damage or loss suffered by buyer due to their lack thereof knowledge or disclosure.

I'm sorry, but I couldn't find any information on a U.S. Supreme Court case titled Avery v. Popper from 1900 or at any other time. It's possible that there might be some confusion about the case name or date. If you have more details, I'd be happy to help further!