Curious Looking Calendar
These days we have planners in all shapes, forms, and sizes and for those of us who don’t want to use physical notebooks, there’s the option of using digital planners. When the OP found these slabs of ivory with the days of the week on the top, little did they know that they were looking at an antique Victorian chatelaine aide memoir from the mid-1800s.
These were made of sheets of bone and would hang from a chain or be kept in the chatelaine’s pocket. As and when needed, they would use them to make notes and appointments for the week to come. If you look closely, it has six pages for Monday to Saturday because a lady would never make appointments on a Sunday.