This room marks the end of the original house. You can see by the door closing it off from the hallway you just stepped through that this was an actual room at one point, and not just a hallway library. In 1914, however, they added three bedrooms and two bathrooms to the second floor, which are just down the steps before you.
The built-in bookcases were also added in 1914. We think they used this as a sewing and linen room prior to the bookcases.
As you travel down the steps to the remaining bedrooms, be aware that there is a handrail at your left.